tag:theconversation.com,2011:/global/topics/phenology-14002/articlesPhenology – The Conversation2024-02-29T17:37:28Ztag:theconversation.com,2011:article/2239302024-02-29T17:37:28Z2024-02-29T17:37:28ZPlants are flowering earlier than ever – here’s how they sense the seasons<p>Hedgerows in mid-February might have traditionally appeared white with snow; this year the white was the work of blackthorn blossoms – a harbinger of spring. Although a welcome sign after a wet and gloomy winter, the early flowering brings unease for experienced season watchers. Has this plant always flowered in mid-February, I wondered, or is something changing?</p>
<p>Fortunately, the science of recording and understanding seasonal events, phenology, has a long history in Britain. <a href="https://www.robertmarsham.co.uk/">Robert Marsham</a>, an 18th-century naturalist, kept records of the appearance of the flowers, birds and insects in his Norfolk village as far back as 1736. Marsham’s descendants continued the recording until 1958. The Woodland Trust maintains the tradition with <a href="https://naturescalendar.woodlandtrust.org.uk/">Nature’s Calendar</a>, a scheme in which members of the public are invited to record various seasonal events.</p>
<p><a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2021.2456">Detailed analysis</a> of almost half a million plant records by scientists in 2022 showed that when all species were considered together the average flowering time in the UK had advanced by a month over the last 40 years. There was variation between species. Hawthorn, the common hedgerow plant, is generally flowering 13 days earlier than it did in the early 1980s while the flowers of the horse chestnut tree appear ten days earlier.</p>
<p>The climate has warmed rapidly since the 1980s. By flowering earlier, plants recognise that winters are becoming shorter and milder. They sense the days getting warmer and alter their spring development in a manner akin to humans feeling warmth on their skin and so stepping out with fewer layers of clothing. The precise mechanisms for detecting these cues differ between plants and animals, but both are responding to the climate as it changes. </p>
<h2>Detecting light and heat without eyes and skin</h2>
<p>Plants detect the shortening days of autumn with a pigment called phytochrome that is particularly sensitive to wavelengths in the red region of the electromagnetic spectrum. The longer autumn nights alter the quality of this red light. While this subtle shift escapes humans (our eyes are not sensitive to this part of the spectrum) a plant can detect this transition and start to change.</p>
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<img alt="A bench next to a woodland at sunset." src="https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578640/original/file-20240228-18-qoad8t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Plants detect subtle changes in red light and instigate dormancy as autumn descends.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/romantic-autumn-mood-sunset-lake-ammersee-690569119">Art180/Shutterstock</a></span>
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<p>Just as the autumn can engineer a drop in the level of the hormone serotonin in our blood, a plant that has sensed winter’s approach will increase the production of a hormone called abscisic acid. This has multiple effects. In deciduous trees, twigs stop growing and develop tough winter buds capable of surviving frost and snow and leaves fall off.</p>
<p>Growth in spring is determined by similar triggers of light length and temperature, but temperature typically has the more significant role. If plants only paid attention to light, they’d run the risk of starting growth when fatal frosts are still a threat or of missing good growing time in mild early spring days. Temperature detection determines when spring flowers appear. This is why global heating is evident in the earlier appearance of these flowers.</p>
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<p><em>Do the seasons feel increasingly weird to you? You’re not alone. Climate change is distorting nature’s calendar, causing plants to flower early and animals to emerge at the wrong time.</em></p>
<p><em>This article is part of a series, <a href="https://theconversation.com/uk/topics/wild-seasons-152175?utm_source=InArticleTop&utm_medium=TCUK&utm_campaign=WS">Wild Seasons</a>, on how the seasons are changing – and what they may eventually look like.</em></p>
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<p>It isn’t fully understood how plants detect temperature. Some of it may be due to a growth-stalling hormone in its cells breaking down when the air falls below a certain temperature, which in turn allows a growth hormone to increase. </p>
<p>While humans have nerves in their skin to detect temperature, plants probably rely on pigments, though the mechanism isn’t fully understood. Heat is part of the same electromagnetic spectrum that phytochrome is sensitive to, so possibly this pigment is involved. Whatever mechanisms are responsible for initiating growth, temperature also determines how fast plants grow.</p>
<h2>Flowers and pollinators out of sync</h2>
<p>Insect pollinators like bees must synchronise their life cycles so that they are on the wing when the blossoms on which they feed emerge. The timing of their emergence from winter is also determined by the effects of temperature and day length and mediated by hormones. </p>
<p>Evolution working on many generations of pollinators has generated a tight link between the emergence of flowers and that of their pollinators. If the appearance of flowers and pollinators isn’t synchronised, the insects have no nectar and the plants aren’t fertilised. </p>
<p>A similar link exists between the emergence of leaves and the insect herbivores that graze on them. The rapidity of climate change and slight differences in how the two groups respond risk breaking this synchrony with serious consequences for both sides.</p>
<p><a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2021.2142">A large study</a> by German scientists looking at when flowers and their pollinators emerged between 1980 and 2020 found a complex picture. Both responded to climate change with earlier flowering and appearances, but the plants had made a greater shift. </p>
<p>There was variation between insect groups, bees and butterflies had shifted in synchrony with the plants, but this wasn’t observed in hoverflies. There was also variation between species of these insects.</p>
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<img alt="A white butterfly on a purple flower." src="https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578642/original/file-20240228-30-erxph1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Plants and insects co-evolved to emerge at roughly the same time in Spring.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/blackveined-white-butterfly-aporia-crataegi-perfect-79443766">Marek Mierzejewski/Shutterstock</a></span>
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<p>Even when plants and their dependent insects change timings in synchrony, the next stage of the food chain may not be so flexible. Oak leaves are fed upon by the oak moth caterpillar. This, in turn, is the primary food of the chicks of birds such as blue tits and pied flycatchers <a href="https://www.nature.com/articles/s41559-018-0543-1">link text</a>. Chicks have hatched at roughly the same time, while oak leaves and caterpillars have appeared earlier and so far remain in synchrony. But for how long?</p>
<p>Blackthorn blossoms remain a welcome relief from winter and a sign that spring is on its way. But they are also a sign of climate change: an unfolding experiment on the timing and synchrony of plants and animals – and the intricate food chains that they are part of.</p><img src="https://counter.theconversation.com/content/223930/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Ashton does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Rising air temperatures mean shorter winters and earlier springs.Paul Ashton, Professor of Botany, Edge Hill UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2009752023-03-14T12:24:27Z2023-03-14T12:24:27ZClimate change threatens spring wildflowers by speeding up the time when trees leaf out above them<figure><img src="https://images.theconversation.com/files/514776/original/file-20230311-17-7x9lo1.jpg?ixlib=rb-1.1.0&rect=23%2C0%2C3970%2C2952&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Native wildflowers, such as these Dutchman’s breeches (_Dicentra cucullaria_) that bloom early in spring are losing access to sunlight as trees leaf out earlier.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/26pTuFq">Katja Schulz/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>For <a href="https://nativeplantherald.prairienursery.com/2020/04/spring-ephemerals-in-the-woodland/">short-lived spring wildflowers</a> such as <a href="https://www.wildflower.org/plants/result.php?id_plant=anqu">wood anemone (<em>Anemone quinquefolia</em>)</a> and <a href="https://www.wildflower.org/plants/result.php?id_plant=dicu">Dutchman’s breeches (<em>Dicentra cucullaria</em>)</a>, timing is everything. These fleeting plants, known as ephemerals, grow in temperate forests around the world, leafing out and flowering early in spring before the trees towering above them leaf out. Emerge too early, and it will still be winter; emerge too late, and it will be too shady under the forest canopy for essential photosynthesis to happen. </p>
<p>Over their evolutionary history, these plants have figured out the best timing for their survival. But climate change is altering spring growing conditions, and plant life is changing along with it. </p>
<p>There are many examples of plants shifting flowering time in response to warming temperatures, such as <a href="http://dx.doi.org/10.1088/1748-9326/ac6bb4">cherry blossoms opening earlier and earlier</a> each year. However, when one part of an ecosystem shifts, will all the organisms that depend on it successfully shift too? Or will they be out of luck? And what if interconnected species respond to change at different rates, leading to disruptions in long-standing ecological relationships?</p>
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<figcaption><span class="caption">Participants in the federally funded USA National Phenology Network collect, store and share data on the timing of life cycle events in plants and animals and how climate change is altering those cycles.</span></figcaption>
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<p>Researchers have been asking these types of questions about phenology – the timing of biological events – <a href="https://press.uchicago.edu/ucp/books/book/chicago/W/bo8829988.html">related to climate change</a> for years. But most studies have focused on plant-animal interactions, like pollinators coming out at the <a href="https://doi.org/10.1042/ETLS20190139">wrong time for flowers</a>. Far fewer have analyzed plant-plant interactions, such as spring ephemerals that need time to grow before trees leaf out above them and block the sunlight.</p>
<p><a href="https://www.rprimacklab.com/">Our research group</a> has investigated the mismatch between understory wildflowers and canopy trees around Concord, Massachusetts, using historical observations recorded by Henry David Thoreau, the author of “<a href="https://www.gutenberg.org/files/205/205-h/205-h.htm">Walden,” his classic account of life in the woods</a>. We found that trees in Concord were more sensitive to spring temperatures than wildflowers were, and that this resulted in earlier tree leaf-out that <a href="https://doi.org/10.1111/ele.13224">reduced available light in the understory</a>. </p>
<p>This finding was an important first step, but we wanted to know whether these patterns persisted in other temperate forests in North America and across the Northern Hemisphere. Our 2023 study shows that <a href="https://doi.org/10.1111/1365-2745.14021">the answer is yes</a>.</p>
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<a href="https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A plant with small purple flowers on the forest floor." src="https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=509&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=509&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=509&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=640&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=640&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514778/original/file-20230311-16-lzomuu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=640&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Round-lobed hepatica (<em>Hepatica americana</em>) is an early-blooming wildflower with blue, white or pink flowers, most often found in shaded woodlands.</span>
<span class="attribution"><a class="source" href="https://plants.ces.ncsu.edu/plants/hepatica-americana/">Frtiz Flohr Reynolds/NC State Extension</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>North American mismatches</h2>
<p>For this research we used specimens from herbariums – collections of plants that have been pressed, dried and cataloged. The plants we examined were collected across eastern North America over the past 100 years. We evaluated over 3,000 pressed plant specimens to chart leafing-out time for trees and flowering time for spring wildflowers. </p>
<p>The vast scale of this study was made possible because herbaria have digitized millions of photographs of plant specimens and <a href="https://naturalhistory.si.edu/research/botany/news-and-highlights/digitized">made them available online</a> over the past decade. Before this resource existed, researchers had to travel to many museums scattered around the country. </p>
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<figcaption><span class="caption">The herbarium at the Royal Botanic Gardens in Kew, England, is one of the world’s largest and supports genetic research on plants from around the globe.</span></figcaption>
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<p>Historical weather records are <a href="https://prism.oregonstate.edu">also available online now</a>. This allows researchers to determine spring temperatures for the year and place where each specimen was collected.</p>
<p>Our study enabled us to confirm the results of our work in Concord. We found that as temperatures warm, deciduous trees across eastern north America are advancing their leaf-out timing faster than native wildflowers are responding.</p>
<p>For example, during cooler springs with 24-hour average March and April temperatures of 41 degrees Fahrenheit (5 degrees Celsius), trees leafed out 13 days after native wildflowers. This gave the flowers almost two weeks of full sun on the forest floor. However, during warmer springs, with average temperatures of 58 F (15 C), trees leafed out only 10 days after native wildflowers. This gave the wildflowers about 25% less full sunlight time during which to photosynthesize. </p>
<p>As spring temperatures warm even further with climate change, we expect wildflowers will have even shorter periods of full sunlight. This can mean a sizable decrease in the flowers’ energy supply and ability to survive, grow and reproduce.</p>
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<a href="https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A pink three-lobed wildflower." src="https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514779/original/file-20230311-3323-eiamcv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Trilliums, like this <em>Trillium grandiflorum</em>, bloom from February through June across North America depending on their location.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Trillium_grandiflorum#/media/File:Trillium_grandiflorum_pink1.jpg">Eric Hill/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>We also observed that trees and wildflowers in the warmer southern part of their ranges advanced their leaf-out and flowering times faster, respectively, than those in colder northern locations. In these zones, we found greater timing differences between trees and wildflowers. This means the potential for phenological mismatch, where native wildflowers are more likely to be shaded out by trees, is greater in the southeast U.S. than in areas farther north.</p>
<h2>Parallels and differences on other continents</h2>
<p>For a 2022 study, we collaborated with colleagues from China and Germany to evaluate over 5,000 tree and wildflower specimens collected over the past 120 years. We wanted to see to whether the phenological mismatches that we documented in North America could also be found in temperate forests of <a href="https://doi.org/10.1038/s41467-022-34936-9">East Asia and central Europe</a>. </p>
<p>Our team found a common pattern across all three continents. Trees and wildflowers are active earlier now than in the past, and they are active earlier in warm years and places. </p>
<p>However, in a surprising twist, we didn’t see the North American pattern of trees being more sensitive than wildflowers on the other two continents. In Europe, wildflowers and canopy trees seemed to be shifting together over time. In Asia, the understory wildflowers were shifting more than the trees — meaning they might get more light, not less, in a warmer future.</p>
<p>The differences we found among the three regions were due primarily to variation in the sensitivities of the trees to temperature. Trees in eastern North America responded more strongly to temperature shifts, while Asian trees responded less strongly.</p>
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<p>These results suggest that eastern North American trees have become especially sensitive to temperature as a way of adapting to this region’s <a href="https://earthathome.org/hoe/ne/climate/#">highly variable climate</a>. In contrast, trees in East Asia are apparently more sensitive to other environmental cues, such as day length, when it comes to the timing of spring growth.</p>
<h2>Informing forest management</h2>
<p>Our results pose questions for further research. If spring temperatures aren’t the primary cues determining leaf-out and flowering times of trees and wildflowers in East Asia, what are those cues? How does the declining spring light window for wildflowers in eastern North America affect their energy budgets and ability to survive, grow and flower?</p>
<p>Another question is whether there are any practical management techniques, such as thinning overstory trees or removing invasive plants, that can help wildflowers deal with the ongoing challenges of climate change. Such strategies could help people appreciate and conserve the full range of plants in the forests we depend on and cherish around the world.</p><img src="https://counter.theconversation.com/content/200975/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard B. Primack receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Benjamin R. Lee receives funding from the National Science Foundation and Morton Arboretum</span></em></p><p class="fine-print"><em><span>Tara K. Miller received funding from the National Science Foundation. </span></em></p>Many beloved wildflowers bloom in early spring, while trees are still bare and the flowers have access to sunlight. Climate change is throwing trees and wildflowers out of sync.Richard B. Primack, Professor of Biology, Boston UniversityBenjamin R. Lee, Postdoctoral Fellow in Biology, University of PittsburghTara K. Miller, Policy Research Specialist, Repair Lab, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1955722022-11-29T14:31:18Z2022-11-29T14:31:18ZWhite butterflies are filling Johannesburg’s skies earlier than usual. Climate change is to blame<figure><img src="https://images.theconversation.com/files/497916/original/file-20221129-26-jn5ydx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Brown-veined white butterflies migrate annually from the Kalahari region to Mozambique.</span> <span class="attribution"><span class="source">Instinctively RDH/Shutterstock</span></span></figcaption></figure><p>Each year around mid-summer, somewhere between December and mid-January, the skies of South Africa’s Gauteng province, including the city of Johannesburg, fill with small white butterflies. Some land in people’s gardens, allowing a closer look at the thin brown markings on their wings. Those markings give the butterflies their name: the brown-veined white butterfly (<em>Benenois aurota</em>). </p>
<p>Their annual migration takes between <a href="https://journals.co.za/doi/epdf/10.10520/AJA00128789_3843">80,000 and 155,000 butterflies</a> per hour from South Africa’s Kalahari region to Mozambique, a journey of hundreds of kilometres via Gauteng. They are leaving the arid Kalahari in search of food and moisture.</p>
<p>The butterflies move in a huge group and their migration is relatively quick – it takes a week or so for most of them to move through Gauteng. The resulting clouds of butterflies are a beautiful spectacle, noticed not just by butterfly enthusiasts and scientists, but by residents.</p>
<p>This year, the butterflies have arrived early. </p>
<p>That may seem unimportant. But, to phenologists like myself, it’s evidence of changes in the environment that require close attention. Phenology refers to the timing of annually recurrent biological events: the <a href="https://theconversation.com/jacarandas-in-parts-of-south-africa-are-flowering-earlier-why-its-a-warning-sign-163554">blossoming of jacaranda trees</a>, for instance, or a mass butterfly migration.</p>
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Read more:
<a href="https://theconversation.com/jacarandas-in-parts-of-south-africa-are-flowering-earlier-why-its-a-warning-sign-163554">Jacarandas in parts of South Africa are flowering earlier: why it’s a warning sign</a>
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<hr>
<p><a href="https://www.nature.com/articles/nature01286">Across the world</a>, phenological events are occurring increasingly earlier as a result of climate change. The temperatures that used to signal the onset of spring for plants and animals are now <a href="https://www.ipcc.ch/report/ar6/wg1/">occurring earlier</a> in most parts of the world. Simultaneously, the timing and amount of precipitation are changing too.</p>
<p>Climate change is intangible to many people. We know it is happening, but our larger surroundings look the same – for now. It’s difficult to feel the 1.1°C post-industrial global temperature increase. But we do notice when the jacarandas flower earlier or butterflies arrive in our gardens earlier. This is important in raising public awareness regarding climate change.</p>
<h2>Media records</h2>
<p>In <a href="https://pubmed.ncbi.nlm.nih.gov/35986753/">an article</a> published earlier this year, my students and I used media reports to quantify how the timing of the annual butterfly migration had changed over nearly 100 years.</p>
<p>The butterfly migration has featured in newspaper reports for many years. More recently, with the advent of social media, these butterflies have also been photographed and posted on Instagram, tweeted, and posted on a range of other social media platforms.</p>
<p>These print and social media records are a gold mine for phenologists. For our research we recorded the date of newspaper articles and social media posts relating to sightings of these butterflies in Johannesburg and used this to quantify changes in the timing.</p>
<p>We also analysed local records of rainfall and daily maximum, minimum and average temperatures measured by the <a href="https://www.weathersa.co.za/home/about">South African Weather Service</a>. Although our butterfly arrival date database extended much further back than many of these climate records, we were able to compare the datasets over the period of overlap to determine the role of climate in driving the changes in timing.</p>
<p>We managed to compile a total of 120 records of the brown-veined white butterflies in Johannesburg. From these, we found that the arrival dates have advanced by 2.9 days per decade over the past century, from approximately mid-January to mid-December. Their November arrival this year is earlier than any of the dates in our record. However, because we must rely on print and social media reporting, it is very possible that it is not the earliest that they have ever arrived.</p>
<p>The reason for the advance in timing relates to complex relationships with climate. The strongest statistical relationship that we found in this study was between the arrival dates and the combination of minimum temperature and precipitation during December, which for the majority of the dataset was the month either before or during the migration. </p>
<p>In summers with warmer conditions, and less rainfall, the butterflies arrived earlier. This year, the onset of rainfall in the <a href="https://journals.co.za/doi/abs/10.1080/03736245.2019.1573151">summer-rainfall zone</a> was much later than usual, and September and October were marked by very hot and dry conditions. Although Gauteng had a wet November, the conditions in the months prior to migration are the most important in determining the timing. </p>
<h2>Assessing threats</h2>
<p>Soon the butterflies will leave Johannesburg, continuing on their journey towards Mozambique. Not all of the butterflies will make it and, due to a short lifespan (just two weeks), even those who reach their end destination won’t live for much longer.</p>
<p>We don’t know for sure when the next group will come through Gauteng. But phenologists will be watching carefully, using data about timing and temperature to assess threats to the butterflies and the ecosystems they inhabit.</p><img src="https://counter.theconversation.com/content/195572/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Fitchett receives funding from GENUS - the DSI-NRF Centre of Excellence for Palaeoscience, the National Research Foundation and from the University of the Witwatersrand University Research Committee Friedel Sellschop Award.. </span></em></p>Across the world, phenological events are occurring increasingly earlier as a result of climate change.Jennifer Fitchett, Associate Professor of Physical Geography, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1903042022-10-26T12:28:10Z2022-10-26T12:28:10ZBy fact-checking Thoreau’s observations at Walden Pond, we showed how old diaries and specimens can inform modern research<figure><img src="https://images.theconversation.com/files/491407/original/file-20221024-11269-blb8a6.jpg?ixlib=rb-1.1.0&rect=22%2C9%2C3044%2C2032&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have used author Henry David Thoreau's notes to inform studies of climate change in eastern Massachusetts.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/vQYNL">Tom Stohlman/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Henry David Thoreau, the environmental philosopher and author of <a href="https://www.google.com/books/edition/Walden/yiQ3AAAAIAAJ?hl=en&gbpv=0">“Walden”</a>, was a keen observer of seasonal change. In 1862, for example, he <a href="https://archive.vcu.edu/english/engweb/transcendentalism/authors/thoreau/autumnal.html">wrote in the Atlantic Monthly</a>: </p>
<blockquote>
<p>“October is the month of painted leaves. Their rich glow now flashes round the world. As fruits and leaves and the day itself acquire a bright tint just before they fall, so the year near its setting. October is its sunset sky; November the later twilight.”</p>
</blockquote>
<p>Over the past 20 years, researchers have used Thoreau’s observations of plant <a href="https://doi.org/10.1890/07-0068.1">flowering</a>, <a href="https://doi.org/10.1111/nph.12647">leaf emergence on trees and shrubs</a>, <a href="https://doi.org/10.1525/cond.2010.100006">bird migration</a> and spring ice melt on Walden Pond to study how these events have changed since the 1850s, largely in response to <a href="https://press.uchicago.edu/ucp/books/book/chicago/W/bo8829988.html">climate change</a>. </p>
<p>Ecologists have also pulled data for modern-day research from museum specimens, <a href="https://doi.org/10.1656/045.026.0309">journals of hunting guides</a> and bird and <a href="https://doi.org/10.1007/s00484-017-1347-8">butterfly club reports</a>. Comparisons with historical records have provided insights into shifts in the natural world caused by climate change and other human influences. Examples include <a href="https://doi.org/10.1016/j.marpolbul.2003.11.004">coral decline in American Samoa</a>, <a href="https://doi.org/10.1016/j.biocon.2004.01.017">amphibian losses in Mexico</a> and <a href="https://doi.org/10.1111/j.1365-2486.2012.02784.x">shifts in birds’ ranges in California’s Sierra Nevada</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/uxtrOsFnvq0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Researchers are using a collection of photographs of British landscapes taken between 1910-1935 to analyze current effects of climate change at those locations.</span></figcaption>
</figure>
<p>But how do scientists know that this historical data is appropriate to use? How can they tell good data from bad? And how can you know whether records you may have, such as an ancestor’s journals or seashell collection, might be useful for science?</p>
<p>We recently published <a href="https://doi.org/10.1093/biosci/biac063">an article in the journal Bioscience</a> that lays out a three-step approach for assessing the quality of historical observations. Using this approach, we believe that scientists can confidently use historical resources to inform studies reaching back to times and places where formal scientific data is not available. </p>
<h2>A three-part test</h2>
<p>Not long after Thoreau died, critics questioned the accuracy of his natural history observations. Writing in 1919, John Burroughs, a leading nature essayist of the time, offered perhaps the <a href="https://www.theatlantic.com/magazine/archive/1919/06/a-critical-glance-into-thoreau/646539/">strongest criticisms</a>. </p>
<p>Burroughs asserted that Thoreau’s “observations are frequently at fault, or wholly wide of the mark.” He questioned whether Thoreau knew basic facts, such as that hickory trees grew in Concord, Massachusetts, and that pine trees had seeds. </p>
<p>To determine whether Burroughs and other critics were right, we propose a straightforward three-step process. </p>
<p>– Is the information collected using rigorous methods that are well documented and clearly described? Modern researchers should be able to repeat them – for example, locating sites where past naturalists worked, making observations over the same number of days per week and following other key parts of their methods.</p>
<p>– How accurate are the observations, such as species identifications? Were they subject to any biases? Can researchers or naturalists replicate aspects of the observations that would be expected to remain consistent over time?</p>
<p>– Does the data have the precision, frequency and rigor that scholars need now? No data is right for all purposes. Modern researchers must decide whether the information can answer the question they are investigating.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RkPBxxpy2b8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In this 2011 video, Boston University biologist Richard Primack explains how he and his research team used Henry David Thoreau’s nature observations from the 1850s to measure the effects of climate change in New England.</span></figcaption>
</figure>
<h2>Was Thoreau a good naturalist?</h2>
<p>When we assessed the rigor, accuracy and utility of Thoreau’s natural history observations, we found that he was indeed a good naturalist. </p>
<p>Thoreau thoroughly documented the dates, locations and descriptions of observations that he made as he walked around <a href="https://www.mass.gov/locations/walden-pond-state-reservation">Walden Pond</a> and greater Concord. We can read in his journals how often and for how long he made these notes. </p>
<p>We compared Thoreau’s notes to modern observations and found that his observations of seasonal events such as leaf out, flowering, fruiting and bird arrivals were highly correlated with modern findings. This told us that Thoreau captured similar patterns. </p>
<p>For example, we can see that the order in which flowers bloom in spring around Concord is nearly the same in Thoreau’s journals as in modern observations. In both data sets, certain species flower early, while other species bloom late in the season.</p>
<p>Thoreau’s historical observations have tremendous utility in research. We and other researchers have used them to learn about the effects of climate change on <a href="https://doi.org/10.1890/07-0068.1">plants</a> and <a href="https://doi.org/10.1525/cond.2010.100006">birds</a> in Concord. Using Thoreau’s findings as a baseline, we have found that spring leaf out and flowering are occurring earlier, but the timing of bird arrivals is not changing much.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Flowers opening on a blueberry bush" src="https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491415/original/file-20221024-11-mgvbna.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">On daily walks around Concord, Mass., Henry David Thoreau observed highbush blueberry (<em>Vaccinium corymbosum</em>) flowers first opening on May 11, 1853. Today, warming has pushed blueberry flowering at least three weeks earlier in the year.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2iWpySb">Gertjian van Noord/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Beyond Thoreau and Walden</h2>
<p>Researchers can use this approach to evaluate other historical observations. For example, between 1904 and 1969, American field biologist <a href="https://mvz.berkeley.edu/joseph-grinnell/">Joseph Grinnell</a> and his colleagues recorded observations of species in California. Their team carefully described most of their methods and collected specimens and photographs to document their work. </p>
<p>However, their sampling methods were sometimes inconsistent, and researchers cannot locate some of their sampling routes. These uncertainties make the Grinnell team’s observations inappropriate to answer questions about changes in the abundance of some species. But their observations are excellent for answering questions about how climate change is altering the ranges of many species, including <a href="https://doi.org/10.1073/pnas.0901562106">birds</a> and <a href="https://doi.org/10.1126/science.1163428">small mammals like mice, voles and chipmunks</a> that Grinnell’s team observed there in the past and that still occur there. </p>
<p>Museum specimens such as <a href="https://doi.org/10.1093/biosci/biz094">dried plants</a>, bird nests and animal skins are another source of historical information. The specimens themselves remove uncertainty around species identification and preserve many physical characteristics that interest researchers. </p>
<p>However, the people who collected the specimens sometimes fail to record precise location information. And some collectors target particular species, locations or seasons, <a href="https://doi.org/10.1111/nph.14855">which can bias what they find</a>. </p>
<p>For example, if a collector targeted spring-flowering plants, their collection may be missing plants that flower later in the year. We urge researchers to <a href="https://doi.org/10.1016/j.tree.2021.08.003">watch for these biases when using historical data</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Visitors view display cases holding preserved animals" src="https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491421/original/file-20221024-6986-t1in47.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Animals and plants in museum collections, such as these in New York’s American Museum of Natural History, are valuable sources of DNA for studies of evolution and biodiversity – but collection methods can affect how useful they are.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-visit-the-american-museum-of-natural-history-on-july-news-photo/1411282889">Michael M. Santiago/Getty Images</a></span>
</figcaption>
</figure>
<p>It’s not uncommon to find historical data sets with little, if any, documentation about when, where and how the data was collected – for example, observations from someone’s daily walks, collections of photographs or a birder’s reports to an ornithological club. Even in these cases, it may be possible to determine how rigorous and accurate the data is.</p>
<p>For example, the frequency of photographs or observations may hint at how often someone made observations. And even poorly documented data can be useful to address some ecological questions, or could <a href="https://doi.org/10.1656/045.026.0309">suggest new hypotheses that deserve further study</a>. </p>
<p>Scientists are searching for more historical data. Following careful evaluation, we may be able to use this information to learn about the effects of climate change, land use practices and other environmental issues. People who have records that might be scientifically valuable should consider contacting ecologists, research stations, natural history clubs and the <a href="https://www.usanpn.org/usa-national-phenology-network">USA National Phenology Network</a>, which collects, stores and shares data on the timing of seasonal events such as bird migration across the U.S.</p><img src="https://counter.theconversation.com/content/190304/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tara K. Miller receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Abe Miller-Rushing has received funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Richard B. Primack receives funding from the US National Science Foundation.</span></em></p>Journals, museum collections and other historical sources can provide valuable data for modern ecological studies. But just because a source is old doesn’t make it useful.Tara K. Miller, PhD Candidate in Biology, Boston UniversityAbe Miller-Rushing, Science Coordinator, Acadia National Park, National Park ServiceRichard B. Primack, Professor of Biology, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1902962022-10-13T12:23:17Z2022-10-13T12:23:17ZBees face many challenges – and climate change is ratcheting up the pressure<figure><img src="https://images.theconversation.com/files/489384/original/file-20221012-18-sw1rgp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5184%2C3880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bees look for water on an outdoor tap in Berlin, Germany during a hot spell, June 19, 2022.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/berlin-bees-try-to-take-water-from-the-thread-of-an-old-tap-news-photo/1241401800">Wolfram Steinberg/picture alliance via Getty Images</a></span></figcaption></figure><p>The extreme weather that has <a href="https://theconversation.com/looking-back-on-americas-summer-of-heat-floods-and-climate-change-welcome-to-the-new-abnormal-190636">battered much of the U.S.</a> in 2022 doesn’t just affect humans. Heat waves, wildfires, droughts and storms also <a href="https://www.fws.gov/initiative/impacts">threaten many wild species</a> – including some that already face other stresses. </p>
<p>I’ve been <a href="https://scholar.google.com/citations?hl=en&user=B1qAtjIAAAAJ">researching bee health</a> for over 10 years, with a focus on honey bees. In 2021, I began hearing for the first time from beekeepers about how extreme drought and rainfall were affecting bee colony health. </p>
<p><a href="https://www.ncei.noaa.gov/access/monitoring/monthly-report/drought/202113">Drought conditions in the western U.S.</a> in 2021 dried up bee forage – the floral nectar and pollen that bees need to produce honey and stay healthy. And <a href="https://www.washingtonpost.com/weather/2021/12/29/wettest-2021-east-us/">extreme rain in the Northeast</a> limited the hours that bees could fly for forage. </p>
<p>In both cases, managed colonies – hives that humans keep for honey production or commercial pollination – were starving. Beekeepers had to feed their bees more supplements of sugar water and pollen than they usually would to keep their colonies alive. Some beekeepers who had been in business for decades shared that they lost 50% to 70% of their colonies over the winter of 2021-2022. </p>
<p>These weather conditions <a href="https://doi.org/10.1093/jisesa/ieaa114">likely also affected wild and native bees</a>. And unlike managed colonies, these important species did not receive supplements to buffer them through harsh conditions. </p>
<p>Each year, the <a href="https://www.usda.gov/">U.S. Department of Agriculture</a> and the <a href="https://www.epa.gov/">Environmental Protection Agency</a> host federal pollinator experts to share the latest scientific findings on bee and pollinator health, and assess the status of these important insects, birds, bats and other species. One clear takeaway from this year’s meeting was that climate change has become a new and formidable stressor for bees, potentially amplifying previously known issues in ways that scientists can’t yet predict but need to prepare for. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6tZTH5KWFqM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Climate change threatens bees around the world. In Australia, large-scale bushfires and drought have killed millions of bees in recent years.</span></figcaption>
</figure>
<h2>The scourge of <em>Varroa</em> mites</h2>
<p>Pollinators contribute <a href="https://ipbes.net/article/press-release-pollinators-vital-our-food-supply-under-threat">an estimated US$235 billion to $577 billion</a> yearly to global agriculture, based on the value of the crops they pollinate. Understanding and mitigating the impacts of climate change on pollinators is key for supporting healthy ecosystems and sustainable agriculture.</p>
<p>Bee health first attracted widespread attention in 2006 with the emergence of <a href="https://www.epa.gov/pollinator-protection/colony-collapse-disorder">Colony Collapse Disorder</a>, a phenomenon where the majority of adult worker bees in a colony disappeared, leaving their honey and pollen stores and some nurse bees behind to care for the queen and remaining immature bees. In the past five years, reported cases have declined substantially. Now, researchers are focusing on what beekeepers call the “four Ps”: parasites, pathogens, pesticides and poor nutrition, as well as habitat loss for wild and native bees. </p>
<p>One of the most severe threats to honey bees over the past several decades has been <em>Varroa destructor</em>, a crablike parasitic mite that <a href="https://doi.org/10.1073/pnas.1818371116">feeds on honey bees’ fat body tissue</a>. The fat body is <a href="https://entomologytoday.org/2019/02/21/inside-look-how-varroa-mite-diet-discovered/">a nutrient-dense organ</a> that functions much like the liver in mammals. It helps bees maintain a strong immune system, metabolize pesticides and survive through the winter. </p>
<p>These are vital functions, so controlling mite infestations is essential for bee health. <em>Varroa</em> can also transmit deadly pathogens to honey bees, such as <a href="https://doi.org/10.1038/s41598-019-47447-3">deformed wing virus</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bee flying, with two brown circular mites clinging to it" src="https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489395/original/file-20221012-21-7erbs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A honey bee carrying two <em>Varroa</em> mites, one above its leg and one on its back.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2hcd9TT">USGS</a></span>
</figcaption>
</figure>
<p>Controlling mite populations is challenging. It requires using an insecticide in an insect colony, or as beekeepers say, “trying to kill a bug on a bug.” It’s hard to find a formula strong enough to kill mites without harming the bees. </p>
<p>Monitoring <em>Varroa</em> takes significant skill and labor, and mites can build up resistance to treatments over time. Researchers and beekeepers are working hard to <a href="https://www.sare.org/publications/a-sustainable-approach-to-controlling-honey-bee-diseases-and-varroa-mites/breeding-for-resistance/">breed <em>Varroa</em>-resistant bees</a>, but mites continue to plague the industry.</p>
<h2>Pesticide microdoses</h2>
<p>Pesticides also harm bees, particularly products that cause sublethal or chronic bee health issues. <a href="https://doi.org/10.1016/j.scitotenv.2022.156857">Sublethal pesticide exposures</a> can make bees less able to <a href="https://doi.org/10.1111/1365-2435.12292">gather forage</a>, <a href="https://doi.org/10.1371/journal.pone.0077547">grow healthy larvae</a> and <a href="https://doi.org/10.1016/j.cois.2018.01.006">fight off viruses</a> and mites. </p>
<p>However, it can be hard to document and understand sublethal toxicity. Many factors affect how bees react to agrochemicals, including whether they are exposed as larvae or as adult bees, the mixture of chemicals bees are exposed to, the weather at the time of application and how healthy a bee colony is pre-exposure.</p>
<p>Researchers are also working to understand <a href="https://theconversation.com/a-common-soil-pesticide-cut-wild-bee-reproduction-by-89-heres-why-scientists-are-worried-155985">how soil pesticides affect ground-nesting wild bees</a>, which represent <a href="https://ento.psu.edu/research/centers/pollinators/resources-and-outreach/disappearing-pollinators/nesting-sites">over 70% of the U.S. native bee</a> population. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bee crawls out of a small hole in the dirt, overhung by grass" src="https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=568&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=568&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=568&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=714&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=714&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487116/original/file-20220928-6297-s2i3ld.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=714&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A ground-nesting bee (<em>Colletes inaqualis</em>) emerging from its burrow.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/9GUDGz">Rob Cruickshank/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Junk food diets</h2>
<p>Like many other species, bees are losing the habitat and food sources that they depend on. This is happening <a href="https://ento.psu.edu/research/centers/pollinators/resources-and-outreach/disappearing-pollinators/habitat-fragmentation">for many reasons</a>. </p>
<p>For example, uncultivated lands are being <a href="https://doi.org/10.1038/s41467-021-22702-2">converted to farmland or developed worldwide</a>. Large-scale agriculture focuses on mass production of a few commodity crops, which reduces the amount of nesting habitat and forage available for bees. </p>
<p>And many farmers often remove pollinator-friendly plants and shrubs that grow around farm lands to reduce the risk of attracting animals such as deer and rodents, which could <a href="https://doi.org/10.1093/biosci/biv152">spread pathogens that cause foodborne illness</a>. Research suggests that these efforts <a href="https://doi.org/10.1111/1365-2664.12707">harm beneficial insects and don’t increase food safety</a>. </p>
<p>As diverse and healthy bee forage disappears, beekeepers <a href="https://doi.org/10.1016/j.jrurstud.2018.10.007">feed their bees more supplements</a>, such as sugar water and pollen substitutes, which are <a href="https://doi.org/10.1007/s13592-015-0386-6">not as nutritious</a> as the nectar and pollen bees get from flowers.</p>
<h2>Climate change is a force multiplier</h2>
<p>Researchers don’t know exactly how climate change will affect bee health. But they suspect it will add to existing stresses. </p>
<p>For example, if pest pressures mount for farmers, bees will be exposed to more pesticides. Extreme rainfall can <a href="https://doi.org/10.1007/s11829-019-09686-z">disrupt bees’ foraging patterns</a>. Wildfires and floods may destroy bee habitat and food sources. Drought may also <a href="https://doi.org/10.1111/gcb.14130">reduce available forage</a> and <a href="https://doi.org/10.3389/fsufs.2021.628802">discourage land managers</a> from planting new areas for bees as water becomes less readily available. </p>
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<p>Climate change could also increase the spread of <em>Varroa</em> and other pathogens. Warmer fall and winter temperatures <a href="https://doi.org/10.21203/rs.3.rs-1394621/v1">extend the period when bees forage</a>. <em>Varroa</em> travel on foraging bees, so longer foraging provides a larger time window for mites and the viruses they carry to spread among colonies. Higher mite populations on bee colonies heading into winter will likely cripple colony health and <a href="https://doi.org/10.1371/journal.pone.0159615">increase winter losses</a>.</p>
<p>Studies have already shown that climate change is <a href="https://doi.org/10.1042/ETLS20190139">disrupting seasonal connections</a> between bees and flowers. As spring arrives earlier in the year, <a href="https://doi.org/10.1098/rspb.2019.0573">flowers bloom earlier</a> or in different regions, but bees may not be present to feed on them. Even if flowers bloom at their usual times and locations, they may <a href="https://doi.org/10.1016/j.cois.2022.100927">produce less-nutritious pollen and nectar</a> under extreme weather conditions. </p>
<p>Research that analyzes the nutritional profiles of bee forage plants and how they change under different climate scenarios will help land managers plant climate-resilient plants for different regions. </p>
<h2>Creating safe bee spaces</h2>
<p>There are many ways to support bees and pollinators. Planting <a href="https://theconversation.com/urban-gardens-are-crucial-food-sources-for-pollinators-heres-what-to-plant-for-every-season-174552">pollinator gardens</a> with regional plants that bloom throughout the year can provide much-needed forage. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/reel/Cg8BHF_DOud/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Ground-nesting native bees need patches of exposed and undisturbed soil, free of mulch or other ground covers. Gardeners can clear some ground in a sunny, well-drained area to create <a href="https://xerces.org/blog/ground-nesting-bees#:%7E:text=If%20you'd%20like%20to,growing%20plants%20to%20prevent%20erosion">dedicated spaces for bees to dig nests</a>. </p>
<p>Another important step is using <a href="https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=17624">integrated pest management</a>, a land management approach that minimizes the use of chemical pesticides. And anyone who wants to help monitor native bees can join <a href="https://xerces.org/community-science">community science projects</a> and use phone apps to submit data. </p>
<p>Most importantly, educating people and communities about bees and their importance to our food system can help create a more pollinator-friendly world.</p><img src="https://counter.theconversation.com/content/190296/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Jennie L. Durant has received funding from the U.S. Department of Agriculture's National Institute of Food and Agriculture. She was a AAAS Science and Technology Fellow at the U.S. Department of Agriculture from 2021-2022.</span></em></p>Honey bees, wild and native bees face threats from parasites, pesticides and habitat loss. Shorter winters, more extreme weather and more habitat destruction won’t help.Jennie L. Durant, Research Affiliate in Human Ecology, University of California, DavisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1879672022-09-02T12:21:48Z2022-09-02T12:21:48ZBirds migrate along ancient routes – here are the latest high-tech tools scientists are using to study their amazing journeys<figure><img src="https://images.theconversation.com/files/482351/original/file-20220901-15-dnl1i1.jpg?ixlib=rb-1.1.0&rect=46%2C0%2C5184%2C3437&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Migrating waterbirds over South Dakota's Huron Wetland Management District on North America's Central Flyway.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/2n6ioDf">Sandra Uecker, USFWS/Flickr</a></span></figcaption></figure><p>Although it still feels like beach weather across much of North America, <a href="https://news.cornell.edu/stories/2018/09/more-4-billion-birds-stream-overhead-during-fall-migration">billions of birds have started taking wing</a> for one of nature’s great spectacles: fall migration. Birds fly south from the northern U.S. and Canada to wintering grounds in the southern U.S., Caribbean and Latin America, sometimes covering thousands of miles. Other birds leave temperate Eurasia for Africa, tropical Asia or Australia. </p>
<p>Using observation records and data collected through <a href="https://nationalzoo.si.edu/migratory-birds/what-bird-banding">bird banding</a>, 20th-century ornithologists roughly mapped general migration routes and timing for most migratory species. Later, using radar at airports and weather stations, they discovered how weather and other factors affect when birds migrate and how high they fly. </p>
<p>Today, technological advances are <a href="https://doi.org/10.1890/080179">providing new insights into bird migration</a> and showing that it is more complex and wonderful than scientists ever imagined. These new and constantly improving technologies are key aids for protecting migratory birds in the face of <a href="https://www.fws.gov/library/collections/threats-birds">habitat loss and other threats</a>.</p>
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<figcaption><span class="caption">Migratory flyways are paths that birds have traveled for centuries. Scientists are working to better understand how birds use these routes.</span></figcaption>
</figure>
<h2>Birding across borders</h2>
<p>The power of the internet has greatly aided migratory bird research. Using the popular <a href="https://ebird.org/home">eBird network</a>, birders all over the world can <a href="https://science.ebird.org/en/status-and-trends/abundance-animations">upload sightings to a central database</a>, creating a real-time record of the ebb and flow of migration. Ornithologists have also learned to use <a href="https://www.faa.gov/air_traffic/weather/nexrad/">NEXRAD</a>, a national network of Doppler weather radars, to visualize <a href="https://birdcast.info/">birds migrating down the North American continent</a>.</p>
<p>Now, scientists are setting up a global network of receiver stations called the Motus Network, which currently has <a href="https://motus.org/">1,500 receivers in 31 countries.</a> Each receiver constantly records the presence of any birds or other animals within a nine-mile (15-kilometer) radius that scientists have fitted with small, lightweight radio transmitters, and shares the data online. The network will become increasingly useful for understanding bird migration as more receiver stations become active along migration tracks. </p>
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<h2>Tracking individual birds via satellite</h2>
<p>Three new technologies are rapidly expanding what we know about bird migration. The first is satellite telemetry of bird movement. Researchers fit birds with small solar-powered transmitters, which send data on the birds’ locations to a satellite and then on to a scientist’s office computer. The scientist can learn where a bird is, the route it took to get there and how fast it travels. </p>
<p>For example, the <a href="https://www.audubon.org/field-guide/bird/bar-tailed-godwit">bar-tailed godwit</a>, a pigeon-sized shorebird, breeds in Alaska and then migrates to New Zealand. Satellite transmitters show that godwits often fly nonstop from Alaska to New Zealand. Recently, a godwit set the record for the longest nonstop flight by a land bird: 8,100 miles (13,000 kilometers) in 10 days, <a href="https://www.audubon.org/news/these-mighty-shorebirds-keep-breaking-flight-records-and-you-can-follow-along">from Alaska to Australia</a>. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/ljr79wpG3L8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bar-tailed godwits have the ability to correct course if they are blown off track on their epic migratory journey.</span></figcaption>
</figure>
<p>Satellite telemetry studies show how much individual birds, even those from the same breeding location, vary in their migratory behavior. Individual differences in migratory behavior are probably due to differences in physical condition, learning, experience and personal preferences. </p>
<p>Another shorebird, the <a href="https://www.allaboutbirds.org/guide/Whimbrel/overview">whimbrel</a>, also makes a phenomenally long journey over the ocean. Satellite telemetry has shown that some whimbrels travel from northwest Canada, across the North American continent to Canada’s east coast, then set off over the Atlantic Ocean on a 3,400-mile (5,400-kilometer), six-day nonstop flight to the coast of Brazil. In total, they may travel <a href="https://doi.org/10.1038/s41598-021-92429-z">6,800 miles (11,000 kilometers)</a>. </p>
<p>Sadly, hunters kill some of these birds when they land to rest on <a href="https://www.wm.edu/news/stories/2011/machi-the-whimbrel-survives-hurricanes-to-die-of-gunfire-123.php">islands in the Lesser Antilles</a>. The unfortunate fate of two satellite-tracked whimbrels has catalyzed a campaign to tighten regulations on <a href="https://www.wm.edu/news/stories/2013/machi-and-goshens-legacy-increased-shorebird-hunting-regulations123.php">shorebird hunting in the Caribbean</a>.</p>
<h2>Geotagging small birds</h2>
<p>Many birds are too small to carry a satellite transmitter. Given the energetic effort required for migration, a device must weigh less than 5% of a bird’s body weight, and many migratory songbirds weigh under 0.7 ounces (20 grams). </p>
<p>An ingenious solution for small birds is a <a href="http://dx.doi.org/10.1126/science.1166664">geolocator tag, or geologger</a> – a tiny device that simply records <a href="https://doi.org/10.1111/jofo.12011">time, location and presence or absence of sunlight</a>. Scientists know the timing of sunrise and sunset on a given date, so they can calculate a bird’s location on that date to within about 125 miles (200 kilometers). </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Colorful songbird with a small geolocation tag attached to its back." src="https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=522&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=522&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482340/original/file-20220901-6551-9rbk6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=522&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A painted bunting equipped with a 0.024-ounce (0.7-gram) solar geolocation datalogger.</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/10.1525/bio.2011.61.9.7">Jeffrey F. Kelly</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Birds carrying geologgers must be recaptured to download the data. That means the bird must survive a migration round trip and return to the same place where it was first captured and tagged. Amazingly, many geologger-tagged small birds do.</p>
<p>Geologgers have shown that <a href="https://www.allaboutbirds.org/guide/Blackpoll_Warbler/overview">Blackpoll warblers</a> – small songbirds that breed in the boreal forests of North America – fly long distances over the Atlantic in fall, heading to the Amazon basin. Birds breeding in eastern North America head out over the Atlantic in maritime Canada or the northeastern U.S. and make a <a href="https://doi.org/10.1098/rsbl.2014.1045">60-hour, nonstop, 1,500-mile (2,500-kilometer) flight</a> to the Greater Antilles. There they rest and recuperate, then continue across the Caribbean to South America. </p>
<p>Blackpolls breeding in Alaska fly across the North American continent before leaving shore on the Atlantic coast and <a href="https://doi.org/10.1002/ecy.2651">flying to South America</a>. In total, they journey 6,600 miles (10,700 kilometers) over 60 days.</p>
<p>Even more amazing, geologgers show that another small songbird, <a href="https://www.audubon.org/field-guide/bird/northern-wheatear">the northern wheatear</a>, migrates from North America to sub-Saharan Africa. Wheatears that breed in Alaska fly 9,100 miles (14,600 kilometers) across Asia to East Africa, taking three months to do so. Those breeding in eastern Canada journey 4,600 miles (7,400 kilometers) across the Atlantic to Europe and then on to West Africa – including <a href="https://doi.org/10.1098/rsbl.2011.1223">a 2,100-mile (3,400-kilometer), four-day nonstop overwater flight.</a></p>
<h2>Recording birds’ night migration calls</h2>
<p>Two hours after sunset in fall, I like to sit outside and listen to birds migrating overhead. Most birds migrate at night, and many give a species-specific “chit,” “zeep” or other call-note while in flight. The calls may serve to keep migrating flocks together, including <a href="https://doi.org/10.1111/evo.14167">different species heading to the same destination</a>. </p>
<p>Ornithologists are using <a href="https://doi.org/10.5751/ACE-00974-120114">automated passive acoustic recording</a> to study these nocturnal calls and identify the species or group of related species that make each sound. The technology is a microphone directed at the sky, connected to a computer that continuously records the sound stream and is aided by sound recognition software. Sometimes it reveals migrants overhead that are rarely seen on the ground. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/seG9otqyvRs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists use infrared cameras and birds’ nocturnal migration calls to assess the risks birds face from colliding with buildings.</span></figcaption>
</figure>
<p>Nick Kachala, an honors student in my lab, set up recording units on three university properties in the fall of 2021. One of the most common migrants recorded was the <a href="https://www.allaboutbirds.org/guide/Gray-cheeked_Thrush/overview">gray-cheeked thrush</a>, a shy bird of the northern boreal forest that is rarely seen in the northeast U.S. during fall migration. He also detected the <a href="https://www.allaboutbirds.org/guide/Dickcissel/overview">dickcissel</a>, a grassland bird that I have never seen in our area. </p>
<p>Many birdwatchers are now building <a href="https://www.audubon.org/news/how-birders-are-boosting-their-yard-lists-while-they-sleep">do-it-yourself backyard recording units</a> to identify the birds flying over their homes during migration.</p>
<h2>Conserving migratory birds</h2>
<p>Radar monitoring indicates that the number of North American migratory birds <a href="http://dx.doi.org/10.1126/science.aaw1313">declined by 14% between 2007 and 2017</a>. There probably are multiple causes, but habitat loss is likely the principal culprit. </p>
<p>Satellite telemetry and geologgers show that there are special stopover sites along migration routes where migrants rest and refuel, such as <a href="https://doi.org/10.1111/ele.13618">the Texas Gulf Coast, the Florida Panhandle</a> and Mexico’s <a href="https://doi.org/10.1017/S0959270917000296">Yucatan Peninsula</a>. Conservation experts widely agree that to protect migratory birds, it is critical to <a href="https://www.allaboutbirds.org/news/bottlenecks-refueling-stations-and-fire-escapes-3-types-of-stopover-sites-migrants-really-need/">conserve these sites</a>. </p>
<p>Effective conservation measures require knowing where and how birds migrate, and what dangers they face during migration. Ornithologists, using these new technologies, are learning things that will help to stop and reverse <a href="https://doi.org/10.1126/science.aac9180">the global decline in migratory birds</a>.</p><img src="https://counter.theconversation.com/content/187967/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tom Langen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Satellite telemetry, tiny geolocation tags and passive acoustic recording are providing new insights into bird migration and vital data for conservation.Tom Langen, Professor of Biology, Clarkson UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1847302022-07-12T12:33:24Z2022-07-12T12:33:24ZLight pollution is disrupting the seasonal rhythms of plants and trees, lengthening pollen season in US cities<figure><img src="https://images.theconversation.com/files/473427/original/file-20220711-13-xmyjzd.jpg?ixlib=rb-1.1.0&rect=0%2C1772%2C3712%2C2160&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some cities never sleep.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/light-trails-on-city-street-against-sky-at-night-royalty-free-image/1311603238">Noam Cohen/EyeEm via Getty Images</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>City lights that blaze all night are profoundly disrupting urban plants’ phenology – shifting when their buds open in the spring and when their leaves change colors and drop in the fall. New research I coauthored shows how nighttime lights are <a href="https://doi.org/10.1093/pnasnexus/pgac046">lengthening the growing season in cities</a>, which can affect everything from <a href="https://doi.org/10.1001/jamanetworkopen.2020.7551">allergies</a> to local economies.</p>
<p>In our study, my colleagues and I analyzed trees and shrubs at about 3,000 sites in U.S. cities to see <a href="https://doi.org/10.1093/pnasnexus/pgac046">how they responded</a> under different lighting conditions over a five-year period. Plants use <a href="https://islandpress.org/books/ecological-consequences-artificial-night-lighting">the natural day-night cycle</a> as a signal of seasonal change along with <a href="https://doi.org/10.1073/pnas.1911117117">temperature</a>.</p>
<p>We found that artificial light alone <a href="https://doi.org/10.1093/pnasnexus/pgac046">advanced the date that leaf buds broke</a> in the spring by an average of about nine days compared to sites without nighttime lights. The timing of the fall color change in leaves was more complex, but the leaf change was still delayed on average by nearly six days across the lower 48 states. In general, we found that the more intense the light was, the greater the difference.</p>
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<p>We also projected the future influence of nighttime lights for five U.S. cities – Minneapolis, Chicago, Washington, Atlanta and Houston – based on different scenarios for future global warming and up to a 1% annual increase in nighttime light intensity. We found that increasing nighttime light would likely continue to shift the start of the season earlier, though its influence on the fall color change timing was more complex.</p>
<h2>Why it matters</h2>
<p>This kind of shift in plants’ biological clocks has important implications for the <a href="https://doi.org/10.1016/j.tourman.2018.08.021">economic</a>, <a href="https://theconversation.com/satellites-zoom-in-on-cities-hottest-neighborhoods-to-help-combat-the-urban-heat-island-effect-182925">climate</a>, <a href="https://doi.org/10.1001/jamanetworkopen.2020.7551">health</a> and <a href="https://doi.org/10.1098/rsbl.2014.0586">ecological</a> services that urban plants provide.</p>
<p>On the positive side, longer growing seasons could allow urban farms to <a href="https://doi.org/10.2134/jeq2013.01.0031">be active over longer periods of time</a>. Plants could also provide shade to cool neighborhoods earlier in spring and later in fall as global temperatures rise.</p>
<p>But changes to the growing season could also increase plants’ <a href="https://doi.org/10.1038/s41586-018-0399-1">vulnerability to spring frost damage</a>. And it can create a mismatch with the timing of other organisms, <a href="https://doi.org/10.1042/ETLS20190139">such as pollinators</a>, that some urban plants rely on.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Charts show the intensity of urban light in seven representative cities" src="https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473542/original/file-20220712-22-1d5slr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Urban light intensity varies among cities, and among neighborhoods within cities.</span>
<span class="attribution"><span class="source">Yuyu Zhou</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>A longer active season for urban plants also suggests an earlier and longer pollen season, which can exacerbate asthma and other breathing problems. A study in Maryland found a <a href="https://doi.org/10.1001/jamanetworkopen.2020.7551">17% increase</a> in hospitalizations for asthma in years when plants bloomed very early.</p>
<h2>What still isn’t known</h2>
<p>How the fall color timing will change going forward as night lighting increases and temperatures rise is less clear. Temperature and artificial light together influence the fall color in a complex way, and our projections suggested that the delay of coloring date due to climate warming might stop midcentury and possibly reverse because of artificial light. This will require more research.</p>
<p>How urban artificial light will change in the future also remains to be seen.</p>
<p>One study found that urban light at night had increased <a href="https://doi.org/10.1126/sciadv.1701528">by about 1.8% per year</a> worldwide from 2012-2016. However, many cities and states are <a href="https://www.ncsl.org/research/environment-and-natural-resources/states-shut-out-light-pollution.aspx">trying to reduce light pollution</a>, including requiring shields to control where the light goes and shifting to LED street lights, which use less energy and have <a href="https://doi.org/10.1111/1365-2664.12927">less of an effect</a> on plants than traditional streetlights with <a href="https://doi.org/10.1038/35036500">longer wavelengths</a>.</p>
<figure class="align-center ">
<img alt="Cars are parked on an old brick residential street at dusk with street lights and trees lining the sidewalks." src="https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473435/original/file-20220711-14-a2ls8a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Baltimore has been converting its streetlights to LED to save money on energy. LEDs also have less of an impact on plants.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cobblestone-street-and-fells-point-neighborhood-at-royalty-free-image/1179432549">Cyndi Monaghan via Getty Images</a></span>
</figcaption>
</figure>
<p>Urban plants’ phenology may also be influenced by other factors, such as carbon dioxide and soil moisture. Additionally, the faster increase of temperature at night compared to the daytime could lead to different day-night temperature patterns, which might <a href="https://doi.org/10.1016/j.agrformet.2019.107832">affect plant phenology in complex ways</a>.</p>
<p>Understanding these interactions between plants and artificial light and temperature will help scientists <a href="https://doi.org/10.1038/s41558-022-01331-7">predict changes in plant processes under a changing climate</a>. Cities are already serving as natural laboratories.</p><img src="https://counter.theconversation.com/content/184730/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yuyu Zhou receives funding from the College of Liberal Arts and Sciences at Iowa State University. </span></em></p>Artificial light is upending trees’ ability to use the natural day-night cycle as a signal of seasonal change.Yuyu Zhou, Associate Professor of Environmental Science, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1812312022-04-21T18:44:57Z2022-04-21T18:44:57ZClimate change is altering the seasonal rhythm of plant life-cycle events<figure><img src="https://images.theconversation.com/files/458261/original/file-20220414-12-lyqvov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Changes in climate affect the timings of various points in the life cycle of plants, including when flowers bloom in spring and when leaves wither in autumn.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>“<em>Si sta come d’autunno sugli alberi le foglie</em>.” </p>
<p>“We are like autumn leaves on branches,” <a href="https://cultura.biografieonline.it/soldati-ungaretti/">Italian poet Giuseppe Ungaretti wrote in his 1918 poem <em>Soldati</em></a> (Soldiers), on the tragedy of human life and war.</p>
<p>If the popular image of autumn is <a href="https://doi.org/10.1177%2F039219216201003804">decadence and nostalgia</a> after the summer heat, spring is the season of rebirth after the darkness and cold of winter. The transformative passing of seasons has historically represented a powerful mental image, rich in symbolism. The seasonal timings of biological events are also an essential aspect of <a href="https://doi.org/10.1016/j.tree.2007.04.003">plant adaptation</a> and can also be of crucial <a href="https://doi.org/10.1007/978-90-481-3335-2_4">economic relevance</a>. </p>
<p>However, as forest ecologists, we have observed that climate change has been modifying the timing of recurrent plant life-cycle events, thus critically affecting the ecosystem. </p>
<h2>The plant’s clock</h2>
<p>In spring, flowers bloom. In summer, fruits ripen. In autumn, leaves change colour and fall. In winter, plants rest. This is <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/phenology">phenology</a> — the study of the timing of recurring life-cycle events. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/W0jjyf7sRY8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The life-cycle of plants, animals and all life forms depends on the environment around them.</span></figcaption>
</figure>
<p>So how do plants recognize the passage of time and the right moment to accomplish growth and reproduction? Like people, plants have their own calendar. A plant’s clock is represented by cycles in the environmental conditions, and the timing of phenological events is <a href="https://doi.org/10.1111/gcb.14619">controlled by climate</a>. </p>
<p>Specifically, plants use a set of triggers to synchronize the timings of growth and reproduction with favourable environmental conditions. </p>
<p>Depending on the species, phenological events are triggered by temperature (autumn and winter chilling and spring warming), photoperiod (length of day), precipitation or, often, a combination of these.</p>
<h2>If climate changes, phenology changes</h2>
<p>Phenology is one of the most sensitive biological indicators of the changing climate. Under the progressive rise in temperature experienced in the last century and the variations in seasonal distribution of rainfall events, the <a href="https://doi.org/10.1111/gcb.14619">environmental triggers usually occur earlier and earlier</a>. </p>
<p>This is why phenological shifts have been observed worldwide, and contextually, it seems that phenological events are occuring earlier year by year. </p>
<p>Japan’s <em>Sakura</em> or cherry blossom season is one of the <a href="https://doi.org/10.1007/s00484-019-01719-9">most evident proofs</a> of this shift. Dating back to the ninth century, the date of flowering, which defines the festival’s timing, has been anticipated in the last century by the rise in average temperatures. </p>
<h2>What is the problem? Spring is cool, right?</h2>
<p>American poet <a href="https://www.goodreads.com/quotes/136895-if-we-had-no-winter-the-spring-would-not-be">Anne Bradstreet</a> said, “If we had no winter, the spring would not be so pleasant.” While this is hyperbolic, we still need to consider that the timings of flowers blooming, fruits ripening and other such phenological events result from a long-lasting adaptation of each species to its surrounding environment.</p>
<figure class="align-center ">
<img alt="A lone green plant in a barren land stretch with dried plants." src="https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458682/original/file-20220419-18-z0vdiu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Changes in the environment can have economic consequences as it affects the quantity and quality of agriculture and forestry products.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The timing of phenological events are calibrated to ensure the perfect environmental condition needed to accomplish the annual cycles of a plant’s life while <a href="https://doi.org/10.1016/j.foreco.2020.118483">minimizing the risk of damage</a>. Changes in these conditions can have ecological as well as economic consequences as they can affect the quantity and quality of agriculture and forestry products. </p>
<p>At the end of the growing season, plants develop dormant buds to protect the sensitive <a href="https://www.britannica.com/science/meristem">meristematic cell layer</a> — tissue in which cells maintain the ability to divide throughout the life of the plant — and suspend activity. Dormancy is an adaptation mechanism evolved in climates with seasons to escape harsh winter conditions. </p>
<p>Warm spring temperatures (called forcing), the increase in day length during spring (photoperiod), and the length and intensity of winter temperatures (<a href="https://doi.org/10.1098/rstb.2011.0186">chilling</a>) reactivate the growth of the <a href="https://www.biologyonline.com/dictionary/apical-bud">apical buds</a> — the buds located at the top of the plant — in the spring. Clearly, temperature has a central and leading role in this process. For this reason, warming can trigger an <a href="https://doi.org/10.1093/treephys/tpaa096">earlier reactivation in spring</a> and a delayed cessation in autumn, or both, <a href="https://doi.org/10.1016/j.foreco.2019.01.005">lengthening the growing season</a>.</p>
<p>Some believe that a longer growing season could enhance carbon uptake and, therefore, the productivity of forests. In some places, such as regions in the northern latitudes or elevated altitudes, trees have profited from a <a href="https://doi.org/10.1016/j.foreco.2020.118483">longer growing season</a> and, more generally, more favourable climatic conditions under global warming. </p>
<figure class="align-center ">
<img alt="Snow and ice cover on a blooming cherry tree." src="https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458260/original/file-20220414-26-5wo0gn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Late frosts in spring and early frosts in autumn, that often accompany longer growing seasons, increase the risk for damage to plants and trees.</span>
<span class="attribution"><span class="source">(AP Photo/Carolyn Kaster)</span></span>
</figcaption>
</figure>
<p>However, an earlier growth reactivation increases the risk of damage due to <a href="https://doi.org/10.1016/j.foreco.2019.01.005">late spring frosts, and lengthening of the growing season increases the risk of damage by early autumn frosts</a>. </p>
<p>If trees cannot adapt, or re-adapt, their phenology with the new climatic conditions, the fitness and growth performance of local populations could be dramatically affected.</p>
<h2>If phenology changes, species interaction changes</h2>
<p>Ecosystems are generally complex and the species within them interact with each other as well as their surrounding environment. Different species can react differently to the changing climatic conditions, potentially leading to dangerous new phenological matches or mismatches. </p>
<p>For example, current climatic conditions create new phenological matches between prey and predators. <a href="https://doi.org/10.1111/gcb.14991">Black spruce may become a key host for the spruce budworm</a> given that the timing of maximum larvae activity could be better synchonized with the timing of yearly shoots development, which increases the risk of severe defoliations for one of the most profitable boreal species in North America. </p>
<p>Climate change can also cause mismatches between plants and their pollinators. Bumblebees represent one of the <a href="https://doi.org/10.1126/science.aaa7031">most important pollinators</a> for several wild species and many varieties of enormous agricultural interest. Bumblebees, given their low heat and cold tolerance, are particularly sensitive to environmental conditions. For this reason, the projected climatic risk for this species is <a href="https://doi.org/10.1126/science.aaa7031">extremely high</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bumblebee sits on a wild flower." src="https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458284/original/file-20220414-14135-yes4wi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bumblebees are extremely sensitive to climate change.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The mutually beneficial plant-pollinator relationship is an essential ecosystem service, specially considering that the pollination done by insects contributes to <a href="https://doi.org/10.1016/j.ecolecon.2008.06.014">9.5 per cent of global food production</a>.</p>
<h2>Action must be taken</h2>
<p>As the climate continues to change, affecting all kinds of ecosystems in the process, we need to be aware of plant phenology and think about how these shifts may directly affect our lives and businesses. </p>
<p>Scientists, today, use observational data to determine how species, populations and communities are vulnerable to these ongoing and projected future changes in climate. This research can be the foundation for essential human intervention, which may influence <a href="https://doi.org/10.1016/j.foreco.2019.01.005">plant distribution through assisted migration</a>, which is the human-assisted movement of species to areas far outside their established range. This will help tree species resynchronize their phenology to the current climatic condition. </p>
<p>Plant phenology is the result of an adaptation. However, adaptation requires time, an amount of time we do not have given the magnitude and rate at which we are observing climate changes. Constantly monitoring the phenological shifts worldwide will allow us to develop sound strategies to protect the most vulnerable ecosystems as well as our businesses. </p>
<p>Besides, we are like autumn leaves on branches, but at least we should try not to fall!</p><img src="https://counter.theconversation.com/content/181231/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roberto Silvestro received the Merit scholarship for international PhD students (PBEEE) assigned by the Fonds de Recherche du Québec - Nature et Technologies (FRQNT). </span></em></p><p class="fine-print"><em><span>Sergio Rossi receives funding from Natural Sciences and Engineering Research Council of Canada, Fonds de recherche du Québec - Nature et technologie, Ministère des Forêts, de la Faune et des Parcs du Québec</span></em></p>Climate change is modifying the timing of recurrent life-cycle events with critical consequences on ecological and economic levels.Roberto Silvestro, PhD candidate, biology, Université du Québec à Chicoutimi (UQAC)Sergio Rossi, Professor, Département des Sciences Fondamentales, Université du Québec à Chicoutimi (UQAC)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1553432021-03-04T13:32:21Z2021-03-04T13:32:21ZJanuary warm spells, March freezes: How plants manage the shift from winter to spring<figure><img src="https://images.theconversation.com/files/387325/original/file-20210302-23-sgg0ra.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C2640%2C1968&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A late snowfall could set back the growth of this budding lilac.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/9GHtrJ">oddharmonic/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Weather patterns across the U.S. have felt like a roller coaster ride for the past several months. December and January were <a href="https://www.ncdc.noaa.gov/sotc/national/202012">significantly warmer than average</a> in many locations, followed by February’s <a href="https://www.nytimes.com/2021/02/13/us/winter-storm-snow-ice.html">intense cold wave</a> and a <a href="https://www.washingtonpost.com/weather/2021/02/26/temperature-swing-central-united-states/">dramatic warmup</a>.</p>
<p>If you’ve ever seen lilac bushes crushed by snowdrifts, then budding on a warm day just a few weeks later, you may wonder how plants tolerate such extremes. I study <a href="https://scholar.google.com/citations?user=XfgB_BUAAAAJ&hl=en">how climate change affects the timing of seasonal events</a> in the life cycles of plants, birds and insects in Massachusetts, so I know that species have evolved here to handle New England’s famously changeable weather. But a warming climate is disrupting weather patterns and testing the abilities of many species to adapt.</p>
<h2>Tolerating cold</h2>
<p>On brutal winter days when temperatures are far below freezing, <a href="https://theconversation.com/is-winter-miserable-for-wildlife-108734">animals hibernate underground or huddle in protected spots</a>. But trees and shrubs have to sit there and take it. The tissues in their trunks, branches and roots are alive. How do they survive the freezing cold?</p>
<p>In autumn, woody plants in many parts of North America start <a href="https://doi.org/10.1016/j.tree.2015.01.004">preparing for winter</a>. When their leaves change color and fall, their twigs, branches and trunks start to lose water. As a result, their cells contain higher concentrations of sugars, salts and organic compounds. </p>
<p>This lowers the freezing point of the cells and tissues, and allows them to survive temperatures far below the normal freezing point of water. The trick has its limits, though, so extreme cold events can still kill certain plants.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Snow-coated tree branches against sunset sky." src="https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=747&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=747&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=747&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=939&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=939&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387307/original/file-20210302-23-1r8c64h.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=939&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trees in cold climates have evolved protections against ice and snow.</span>
<span class="attribution"><span class="source">Richard Primack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Tree and shrub roots remain largely unchanged and inactive during winter, relying on insulation from snow and soil for protection. For the most part, the temperature of the soil around roots stays at or above freezing. Soil, fallen leaves and persistent snow layers insulate the ground above the roots and prevent it from losing heat.</p>
<h2>The surprising danger of spring frosts</h2>
<p>After plants stoically withstand cold winters, early spring brings new dangers. Plants need to leaf out as early as they can in spring to take full advantage of the growing season. But this involves pumping water into their developing leaves, which reduces the concentration of sugars, salts and organic compounds in their tissues and removes their winter protection from cold. </p>
<p>Each species has a <a href="https://doi.org/10.1111/nph.12892">characteristic leaf-out time</a>. Early-leafing species such as blueberries and willows are the gamblers of the plant kingdom. Later species, like oak and pine, are the cautious and conservative types. For any species, leafing out too early is a risk because late frosts can damage or kill young leaves. </p>
<p>Flowers are also vulnerable to unpredictable spring frosts because they contain lots of water. If the flowers of fruit trees, such as apples, are killed by frost, the trees won’t produce fruit later in the summer. Late frosts also can cause disappointingly short flowering seasons for early-flowering ornamental plants such as forsythias and magnolias. </p>
<h2>Plant wake-up calls</h2>
<p>To guard against frost and still take advantage of the full growing season, trees and shrubs have developed three ways to know when it is time to start growing in spring. </p>
<p>First, plants have winter chilling requirements: They hold on to winter dormancy until they have been exposed to a certain number of cold winter days. This trait helps them avoid leafing or flowering during abnormally warm periods in midwinter. </p>
<p>Second, plants also have spring warming requirements that promote growth after they experience a certain number of warm days each spring. This feature helps them start to grow as soon as it is warm enough. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="New green leaves on a rhododendron bush." src="https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387316/original/file-20210302-19-jtjsin.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">For woody plants like this rhododendron, the timing of spring leaf-out is a balance between maximizing their growing seasons and avoiding late frosts.</span>
<span class="attribution"><span class="source">Richard Primack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Third, some plants also have a <a href="http://www.biologyreference.com/Ph-Po/Photoperiodism.html">photoperiod</a> response, which means they react to the length of time they are exposed to light in a 24-hour period. This prepares them to leaf out as days get longer and warmer in the spring. Beech trees have both a warming requirement and a photoperiod response, but the temperature requirement is much stronger, so they get going after just a few warm days in late spring.</p>
<p>Interestingly, North American trees such as red maple and black birch are more cautious and conservative than European and East Asian trees. The weather in eastern North America is more variable, and the threat of late spring frosts is higher here than in those regions. As a result, North American trees have evolved to leaf out a few weeks later than comparable trees from Europe and East Asia.</p>
<h2>Climate change scrambles the signals</h2>
<p>Plants are highly attuned to temperature signals, so warming driven by climate change is making it harder for many species to withstand winter cold and spring frosts. As spring temperatures get warmer than in the past, trees such as apples and pears may respond by leafing out and flowering <a href="https://www.americanscientist.org/article/spring-budburst-in-a-changing-climate">several weeks earlier than normal</a>. This can increase their vulnerability to late frosts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cherry branch with blooms and wilted dark leaves." src="https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=481&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=481&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=481&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=604&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=604&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387320/original/file-20210302-13-1tn11ts.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=604&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The leaves on this cherry tree have suffered damage from a late frost.</span>
<span class="attribution"><span class="source">Richard Primack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Such late frosts are <a href="https://doi.org/10.1111/geb.13088">becoming more common</a> because <a href="https://theconversation.com/what-exactly-is-the-polar-vortex-153958">climate change is destabilizing the jet stream</a>, leading it to dip much farther south, bringing bursts of unusually cold weather.</p>
<p>In 2007, an exceptionally warm period in March <a href="https://doi.org/10.1111/j.1469-8137.2011.03803.x">triggered trees to leaf out</a> across the eastern and central United States. A hard frost in April then killed the young leaves and flowers of oaks, hickories and other tree species. The trees were able to produce a second crop of leaves, but could not fully replace the leaves they’d lost, which quite likely stunted their growth for that year. </p>
<p>Insect pests also pose an increasing threat to plants. Harsh winter weather holds in check many insects found in northern climates, such as <a href="https://www.nrs.fs.fed.us/disturbance/invasive_species/hwa/">hemlock woolly adelgids</a> and <a href="https://www.aphis.usda.gov/aphis/maps/plant-health/eab-storymap">emerald ash borers</a>. As winters become milder, these insects are more likely to survive, move further northward, cause major outbreaks and damage trees. </p>
<p>Warmer winters also lead to more days when the ground is bare. Cold snaps that occur when there is no insulating layer of snow can <a href="https://theconversation.com/climate-change-is-shrinking-winter-snowpack-which-harms-northeast-forests-year-round-103410">freeze the soil and kill roots</a>. Tree and shrub branches then die back because the damaged roots cannot supply enough water and nutrients. In extreme cases, the plants may die. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/4pSYC8g5oVM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The U.S. Department of Agriculture’s Plant Hardiness Zone Map shows that these zones – areas where various plant species are most likely to thrive – are shifting northward as climate change warms the U.S.</span></figcaption>
</figure>
<p>In coming decades, many cold-loving tree species such as spruces and firs will become less abundant when they are not able to handle <a href="https://www.fs.fed.us/nrs/pubs/gtr/gtr_nrs173.pdf">new challenges associated with a warmer climate</a>. In the Northeast U.S., native species such as sugar maple and beech will be gradually replaced by native species from farther south, such as oaks and hickories. And nonnative species, such as <a href="https://doi.org/10.1093/treephys/tps092">Norway maples</a>, are taking advantage of these disruptions to disperse into forests from roadsides and neighborhoods.</p>
<p>Similar shifts are happening in many places as climate change alters the signals plants rely on to mark the changing seasons.</p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>.]</p><img src="https://counter.theconversation.com/content/155343/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard B. Primack does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Trees and shrubs in cold-weather climates rely on certain signals, such as temperature and light, to know when to leaf out and bloom. Climate change is scrambling those signals.Richard B. Primack, Professor of Biology, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1525212021-02-03T19:59:46Z2021-02-03T19:59:46ZCitizen scientists are filling research gaps created by the pandemic<figure><img src="https://images.theconversation.com/files/382062/original/file-20210202-19-1ka34wf.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2464%2C1704&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A volunteer looks for waterbirds at Point Reyes National Seashore in California during the National Audubon Society's annual Christmas Bird Count.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/Cfe8RK">Kerry W/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The rapid spread of COVID-19 in 2020 disrupted field research and environmental monitoring efforts worldwide. Travel restrictions and social distancing forced scientists to <a href="https://theconversation.com/covid-19-is-eroding-scientific-field-work-and-our-knowledge-of-how-the-world-is-changing-137045">cancel studies</a> or pause their work for months. These limits measurably <a href="https://www.nature.com/articles/d41586-020-02198-4">reduced the accuracy of weather forecasts</a> and created data gaps on issues ranging from <a href="https://www.audubon.org/news/for-scientists-who-study-birds-spring-without-precedent">bird migration</a> to <a href="https://www.edweek.org/education/education-department-delays-civil-rights-data-collection-citing-covid-19/2020/07">civil rights in U.S. public schools</a>. </p>
<p>Our work relies on this kind of information to <a href="https://www.usanpn.org/usa-national-phenology-network">track seasonal events in nature</a> and understand how <a href="https://scholar.google.com/citations?user=3FUDzuIAAAAJ&hl=en">climate change</a> is <a href="https://scholar.google.com/citations?user=dtI67UcAAAAJ&hl=en">affecting them</a>. We also <a href="https://www.semanticscholar.org/author/Erin-E.-Posthumus/5286364">recruit and train citizens</a> for community science – projects that <a href="https://www.citizenscience.org/">involve amateur or volunteer scientists in scientific research</a>, also known as citizen science. This often involves collecting observations of phenomena such as <a href="http://www.inaturalist.org">plants and animals</a>, <a href="https://www.cocorahs.org/">daily rainfall totals</a>, <a href="https://www.chesapeakemonitoringcoop.org/">water quality</a> or <a href="https://scistarter.org/target-asteroids">asteroids</a>.</p>
<p>Participation in many community science programs has skyrocketed during COVID-19 lockdowns, with some programs reporting <a href="https://insideclimatenews.org/news/22062020/citizen-science-coronavirus">record numbers of contributors</a>. We believe these efforts can help to offset data losses from the shutdown of formal monitoring activities. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/VqyCUlXxFQo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Nature’s Notebook is a community-based science project that invites participants to track seasonal changes in plants and animals.</span></figcaption>
</figure>
<h2>Why is uninterrupted monitoring important?</h2>
<p>Regular, long-term tracking of phenomena such as plant and animal abundance, composition and activity is critical for understanding change. It enables researchers to see the impacts of <a href="https://theconversation.com/heres-how-forests-rebounded-from-yellowstones-epic-1988-fires-and-why-that-could-be-harder-in-the-future-101495">natural disturbance events, such as wildfires</a>, and <a href="https://openresearch-repository.anu.edu.au/handle/1885/130886">human activities, such as construction and development</a>. Long-term studies offer insights into patterns and processes that can’t be derived from shorter studies, and help experts make better predictions about the future. </p>
<p>Interruptions in monitoring make it harder to accurately assess changes. If those disruptions coincide with extreme events, such as a major hurricane, experts miss opportunities to understand the full impacts of those events.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man holding plastic bottles stands in stream." src="https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382068/original/file-20210202-19-bvwtmu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A researcher takes water samples at the Coweeta Long-Term Ecological Research site in North Carolina’s Appalachian Mountains.</span>
<span class="attribution"><a class="source" href="https://lternet.edu/site/coweeta-lter/">U.S. LTER</a></span>
</figcaption>
</figure>
<p>The U.S. has several long-term ecological monitoring programs, including the <a href="https://www.neonscience.org/impact/observatory-blog/observatory-status">National Ecological Observatory Network (NEON)</a>, the <a href="https://lternet.edu/">Long Term Ecological Research Network</a> and federal <a href="https://www.nps.gov/im/index.htm">inventory and monitoring programs</a>. Many state and local government agencies carry out similar activities. The pandemic has <a href="https://www.neonscience.org/impact/observatory-blog/observatory-status">significantly disrupted</a> all of these programs.</p>
<h2>Reasons to engage the public in science</h2>
<p>Community science is a strong complement to formal research. By engaging willing volunteers, community programs yield <a href="https://doi.org/10.1016/j.biocon.2020.108753">much more data</a> and cover larger areas than professional scientists can achieve on their own.</p>
<p>We help manage two popular biodiversity-themed community science programs in the U.S.: <a href="http://www.e-butterfly.org/">eButterfly</a>, a program for tracking butterfly sightings, and <a href="http://www.naturesnotebook.org">Nature’s Notebook</a>, a program for tracking seasonal activity in plants and animals. Scientists have used data contributed by participants in these programs to <a href="https://doi.org/10.1016/j.rse.2018.06.047">verify information collected by satellites</a>, determine the <a href="https://doi.org/10.1111/gcb.14447">conditions associated with flowering</a> in different species of plants, and predict how climate change will <a href="https://doi.org/10.1016/j.agrformet.2019.107803">shift plant species’ ranges</a> in the future. </p>
<p>Observations contributed to other community science programs have helped to <a href="https://www.discovermagazine.com/the-sciences/citizen-science-helps-discover-thirty-new-species-where-you-would-least-expect-it">document new insect species</a>, <a href="https://science.nasa.gov/get-involved/citizenscience/five-extraordinary-citizen-science-discoveries">discover exoplanets</a> and even <a href="https://vector.childrenshospital.org/2017/02/honoring-rare-disease-citizen-scientists/">find cures for rare diseases</a>. Globally, <a href="https://doi.org/10.1016/j.biocon.2014.10.021">millions of people</a> participate in <a href="https://scistarter.org/">thousands of projects</a>, resulting in data valued at more than <a href="https://doi.org/10.1016/j.biocon.2014.10.021">US$1 billion annually</a>.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CJ1V8MWgcjS","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Community science programs <a href="http://osupress.oregonstate.edu/book/diary-of-citizen-scientist">also benefit participants</a>. Joining a community science program can make people more science-literate and help pull back the curtain on how scientific work is done. It also deepens their sense of place and increases their understanding and appreciation for the plants and animals they monitor. We have frequently heard from our participants that making observations has enabled them to see and experience much more in places they know well, and to enjoy those places all the more.</p>
<h2>Community science to the rescue</h2>
<p>As offices and schools closed in the spring of 2020, many Americans turned to community science programs in search of stimulating and meaningful activities for <a href="https://mashable.com/article/citizen-science-for-kids-summer/">children</a> and <a href="https://www.csmonitor.com/Science/2020/0701/Lockdowns-are-turning-cooped-up-residents-into-citizen-scientists">adults</a> alike. And despite COVID-19 restrictions, volunteer data collectors have persisted through the pandemic. </p>
<p>In a recent analysis of activity in biodiversity-themed community science programs during COVID-19 lockdowns, we found that participation generally held steady or increased in the spring of 2020. Two popular programs, <a href="https://www.inaturalist.org/">iNaturalist</a> and <a href="http://ebird.org">eBird</a>, both grew. Participation in Nature’s Notebook and eButterfly declined slightly, though volunteers still logged many critical observations. What’s more, community science volunteers in these programs and others have <a href="https://www.vox.com/future-perfect/22177247/citizen-science-amateur-backyard-birding-astronomy-covid-pandemic">kept at it</a> even as lockdowns have relaxed.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/uM4NYOdTTfg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Plant ecologist Chad Washburn explains how the Naples Botanical Garden in Florida uses citizen science research to study plant distribution, flowering times and range.</span></figcaption>
</figure>
<h2>How good is community data?</h2>
<p>One common question about community science projects is whether data collected by volunteers is reliable. This is a valid concern, since many program participants are not formally trained as scientists. </p>
<p>Organizations that run community science programs typically go to great lengths to ensure data quality. To avoid recording erroneous observations, project leaders provide extensive training and support materials. They also construct data entry apps so that volunteers can’t mistakenly input dates in the future, and flag inconsistent reports for review. Several biodiversity-themed programs, including iNaturalist, <a href="https://support.ebird.org/en/support/solutions/articles/48000795278-the-ebird-review-process">eBird</a> and eButterfly, engage expert reviewers to evaluate and verify reports. </p>
<p>According to a 2018 review by the National Academies of Science, Engineering and Medicine, on average, volunteer contributors yield reliable data points about <a href="https://www.nap.edu/catalog/25183/learning-through-citizen-science-enhancing-opportunities-by-design">75% of the time</a>. For some programs, such as <a href="https://doi.org/10.1007/s00484-014-0892-7">Nature’s Notebook</a> and <a href="https://doi.org/10.1016/j.biocon.2018.02.027">eBird</a>, accuracy is over 90%.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/XLk03c6ypEc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">SciStarter is a database that volunteers can use to find community science opportunities across the U.S. throughout the year.</span></figcaption>
</figure>
<h2>How to get involved</h2>
<p>Your observations can help fill critical gaps that COVID-19 closures have created. Contributions to <a href="http://inaturalist.org">iNaturalist</a>, <a href="http://ebird.org">eBird</a>, <a href="http://www.e-butterfly.org/">eButterfly</a> or <a href="http://www.naturesnotebook.org">Nature’s Notebook</a> are welcome any time of the year, but spring is an ideal time to contribute observations to biodiversity-themed programs to help document plant and animal response to changing seasonal conditions. For example, participants in Nature’s Notebook will help document whether <a href="https://theconversation.com/spring-is-arriving-earlier-across-the-us-and-thats-not-always-good-news-129967">springtime plant and animal activity is early</a> amid the ongoing effects of climate change.</p>
<p>The 2021 <a href="https://citynaturechallenge.org/">City Nature Challenge</a>, an effort using iNaturalist to document urban biodiversity in brief, focused events, will run in late April and early May in cities worldwide. Another event, <a href="https://ebird.org/globalbigday">Global Big Day</a> – a single day focused on celebrating and recording birds worldwide – is scheduled for May 8. Even if you’ve never thought of yourself as a scientist, you can help scientists collect data that expand our understanding of the Earth and how it works.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p><img src="https://counter.theconversation.com/content/152521/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The University of Arizona receives funding from the U.S. Geological Survey, the U.S. Fish & Wildlife Service, the National Science Foundation, and the National Aeronautics and Space Administration to fund the USA National Phenology Network.</span></em></p><p class="fine-print"><em><span>Kathleen Prudic does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>COVID-19 kept many scientists from doing field research in 2020, which means that important records will have data gaps. But volunteers are helping to plug some of those holes.Theresa Crimmins, Director, USA National Phenology Network, University of ArizonaErin Posthumus, Outreach Coordinator and Liaison to the U.S. Fish & Wildlife Service, University of ArizonaKathleen Prudic, Assistant Professor of Citizen and Data Science, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1408562020-07-08T10:51:21Z2020-07-08T10:51:21ZHow animals are coping with the global ‘weirding’ of the Earth’s seasons<figure><img src="https://images.theconversation.com/files/345291/original/file-20200702-57-lzb6c8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4238%2C2950&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Yellow-bellied marmots are a North American species of ground squirrel.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/yellow-bellied-marmot-on-ridge-near-104145308">Fremme/Shutterstock</a></span></figcaption></figure><p><a href="https://www.bbc.co.uk/news/science-environment-52921479">The UK’s weather did a somersault</a> in the first half of 2020, as the wettest February on record gave way to the sunniest spring. Climate change has warped the environmental conditions that might be considered normal, creating progressively weirder seasons that cause havoc for society. Longer, drier summers increase the risk of crop failure and fires, floods engulf homes, and less winter snowfall and earlier thaws threaten freshwater supplies.</p>
<p>But how do animals cope? Many species have evolved life cycles and strategies for coping with the seasons over millions of years, particularly those in temperate to arctic and alpine environments. Here, seasonal variability is large and predictable. Short and mild summers produce bursts of vegetation and food, the perfect time to give birth to young that can forage to develop their fitness. Long, harsh winters when food is scarce have shaped animals to largely depend on fat reserves for energy, and in extreme cases, to hibernate or migrate.</p>
<p>But as species come to inhabit seasons that no longer resemble those they evolved in, their chances of survival are governed less by their own careful adaptations, and more by the capricious weather. For species eking out an existence in seasonal climates, winter and summer produce distinct challenges of their own. </p>
<h2>Climate change and seasonal survival</h2>
<p>In <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.1918584117">new research</a>, we explored how yellow-bellied marmots in the Colorado Rocky Mountains have responded to climate change. Since the 1970s, every marmot pup born at the study site has been marked, and its life followed year after year. </p>
<p>Marmots are large, burrowing ground squirrels, and they have a distinct seasonal life cycle, with a four-month period during the spring and summer when they’re active and need to gain weight by foraging on plants, and an eight-month period of hibernation during autumn and winter. Marmots, like other burrowing and herbivorous mammals, help shape important habitats and serve as prey for many predators. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343958/original/file-20200625-33519-1bw1u6p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The study site on arrival – thick snow as far as the eye can see.</span>
<span class="attribution"><span class="source">Line Cordes</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>When I first arrived at the <a href="https://www.rmbl.org/">alpine field station</a> in April, I was amazed by the thick layer of snow that reached the roofs of the small wooden cabins dotted around the town of Gothic, named after Gothic Mountain which looms above it. But spring set in and the snow melted, and by midsummer, wildflowers transformed the valley floor.</p>
<p><a href="https://www.theatlantic.com/science/archive/2017/01/billy-barr-climate-change/512198/">Climate records</a> painted a gloomier picture, though. Over the past 40 years, winters have warmed by between two and four degrees Celsius on average, while annual snowfall has declined by three and a half metres. Summers have warmed by two degrees Celsius, lengthened by about 50 days and changed from predominantly wet to predominantly dry.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/343957/original/file-20200625-33528-13yfbiv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Summer is warmer, longer and earlier each year.</span>
<span class="attribution"><span class="source">Line Cordes</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>During this time, the chance of marmots surviving a summer has increased, but the chance of surviving the winter hibernation has decreased. The biggest changes in seasonal survival have been noted among younger age classes (the pups and one-year-olds). </p>
<p>We found that lower winter survival tended to be the result of conditions during the previous summer, when heat and drought likely reduced foraging conditions for marmots, leaving them in poor stead for hibernation. </p>
<p>Whether a marmot survived a summer depended on conditions in both seasons. Pups were more likely to survive the summer if it followed a winter with low snowfall. This was most likely because the mothers of these pups were in better condition as forage plants became available sooner after hibernation. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/344544/original/file-20200629-155339-1pvv542.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A marmot pup.</span>
<span class="attribution"><span class="source">Graeme Shannon</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Unexpectedly, one-year-olds survived better when summers were longer and warmer. It may be that yearlings with their smaller body size are less prone to heat stress compared to adults. Nevertheless, we suspect that their resilience may not last as summers continue to warm and become drier. </p>
<p>Simply focusing on the survival of a species over the entire year may disguise these more dramatic seasonal responses to climate change, lulling us into a false sense of security. And contrasting seasonal responses don’t necessarily cancel each other out. For the marmots, the net change over the year was negative for pups, positive for yearlings, while there was no change for adults. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/animals-will-struggle-to-adapt-fast-enough-to-cope-with-climate-change-study-finds-120857">Animals will struggle to adapt fast enough to cope with climate change, study finds</a>
</strong>
</em>
</p>
<hr>
<p>The fact that climate change can result in beneficial conditions in one season, and difficult conditions in another has potentially wide-ranging consequences for the persistence of species occupying temperate to more extreme habitats, such as deserts, mountains and polar regions, where the most rapid changes in climate are being observed. Similar findings have emerged from other species around the world, from <a href="https://science.sciencemag.org/content/sci/363/6427/631.full.pdf">meerkats</a> in the Kalahari Desert to <a href="https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.2141?casa_token=bcoHd_UJEGcAAAAA:_t94cyX3IVQHY4CAYNdeRKgHsLBIq0eXOxCXn7oJUUCZNypwmiFJGNvQg8Rkp9fKRQUR5PYLGPBcyA">bighorn sheep</a> in the Canadian Rocky Mountains. </p>
<p>For wildlife living near the poles or near mountain tops, like marmots, there is nowhere to go when conditions slide further and further from optimal.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1140856">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/140856/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Line Cordes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research on marmots in the US reveals how the topsy-turvy seasons are causing havoc among wildlife.Line Cordes, Lecturer in Marine Population Ecology, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1370452020-05-19T12:17:32Z2020-05-19T12:17:32ZCOVID-19 is eroding scientific field work – and our knowledge of how the world is changing<figure><img src="https://images.theconversation.com/files/334157/original/file-20200511-49546-1auahd7.jpg?ixlib=rb-1.1.0&rect=18%2C0%2C2048%2C1358&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Collecting data on invasive plants, Santa Monica Mountains National Recreation Area, California.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/VSnKr3">Connar L'Ecuyer/NPS</a></span></figcaption></figure><p><em>Editor’s note: Summer is prime time across much of North America for scientists to do field research outdoors. But this year the COVID-19 pandemic is forcing many researchers to cancel or scale back their plans. We asked two scholars to explain the long-term effects of a missed or downscaled field research season.</em></p>
<p><em>Richard B. Primack, Boston University</em></p>
<h2>Holes in the data</h2>
<p>For the first time in 50 years, ornithologists at the <a href="https://www.manomet.org/">Manomet nature observatory</a> in Plymouth, Massachusetts are not opening their mist nets every weekday at dawn to catch, measure and band migrating songbirds. Due to the coronavirus pandemic, the center has essentially canceled its spring field season and will be doing only very limited sampling. Going forward, its long-term banding data will contain only a fraction of the usual information on songbird migrations during the spring of 2020. </p>
<p>Across the world, field stations, nature centers and universities have <a href="http://dx.doi.org/10.1016/j.biocon.2020.108571">shut down long-term research</a> to protect scientists, staff, students and volunteers from COVID-19. There’s good reason for this step, but it comes at a cost.</p>
<p>Collecting data over many years allows scientists to detect gradual trends and short-term anomalies in the health of forests, bays and other ecosystems and biological communities. Long-term research has been crucial in detecting how climate change is affecting the <a href="http://dx.doi.org/10.1126/science.1206432">abundance and distribution of species</a> and the timing of spring events, such as <a href="https://doi.org/10.1371/journal.pone.0222232">bird migrations</a> and <a href="https://doi.org/10.1111/ele.13224">plant flowering</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334152/original/file-20200511-49579-r7t7jl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Marking snowmelt plots at the Niwot Ridge Long-Term Ecological Research site in Colorado.</span>
<span class="attribution"><a class="source" href="https://lternet.edu/site-image-galleries/?site_id=1920">E. Zambello/LTER Network</a></span>
</figcaption>
</figure>
<p>Multi-year data has been vital to understanding how ecosystems bounce back after major disturbances like hurricanes and <a href="https://theconversation.com/heres-how-forests-rebounded-from-yellowstones-epic-1988-fires-and-why-that-could-be-harder-in-the-future-101495">wildfires</a>. Long-term research has informed policies addressing <a href="https://lternet.edu/findings/acid-rain/">air and water pollution</a> and <a href="https://doi.org/10.1016/j.biocon.2016.03.031">wildlife conservation</a>in ways that would have been impossible through short-term studies alone.</p>
<p>Since 1980, the U.S. National Science Foundation has supported a network of <a href="https://lternet.edu/site/#">Long Term Ecological Research sites</a> that now spans 28 locations, from northern Alaska to Antarctica and across North America. These sites are leaders in detecting effects of air pollution, land use and urbanization on ecosystems. The data they produce is available to the public and the scientific community.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=786&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=786&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=786&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=988&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=988&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334151/original/file-20200511-30864-1kjnn2c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=988&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sites in the U.S. Long-Term Ecological Research network, identified by their acronyms.</span>
<span class="attribution"><a class="source" href="https://lternet.edu/documents/lter-network-map/">LTER Network</a></span>
</figcaption>
</figure>
<p>Many long-term studies also take place in national parks, where researchers track subjects like water quality, wetland health and endangered species. In a normal year, armies of researchers and students would be at work in national parks and Long-Term Ecological Research sites. Now, however, just small groups are collecting data, aided by automated equipment.</p>
<h2>Working solo</h2>
<p>Some small-scale projects are managing to continue. Over the past 18 years, <a href="https://www.rprimacklab.com">my students</a> <a href="https://scholar.google.com/citations?user=XfgB_BUAAAAJ&hl=en">and I</a> have recorded <a href="https://doi.org/10.1890/07-0068.1">wildflower flowering</a> and <a href="https://www.americanscientist.org/article/spring-budburst-in-a-changing-climate">the first appearance of spring leaves</a> in Concord, Massachusetts, repeating observations made by Henry David Thoreau in the 1850s. </p>
<p>We’re doing this to study the <a href="https://press.uchicago.edu/ucp/books/book/chicago/W/bo8829988.html">ecological effects of climate change</a>. Our studies have shown that plants are flowering about 10 days earlier in the spring than they did in Thoreau’s time. We have also found that cold-loving northern wildflower species are becoming less abundant, and nonnative species are increasing.</p>
<p>Now I wear a mask, go out early in the mornings when few people are on the trails and work without students. None of this is how we typically work, but it allows me to continue this research and capture anomalies that might occur this year. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=582&fit=crop&dpr=1 754w, https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=582&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/332010/original/file-20200501-42903-1ndfi60.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=582&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Richard Primack wears a face mask while repeating Henry David Thoreau’s spring flowering and leafing observations in Concord, Massachusetts.</span>
<span class="attribution"><span class="source">Richard Primack</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>But maintaining a few long-term studies won’t make up for irreplaceable losses to science that will occur this year, especially for two-year experimental studies that were supposed to start or end this year. My colleagues and I hope that this pandemic ends soon, so that scientists can get back to analyzing the long-term workings of ecosystems – and the ecological impacts of coronavirus.</p>
<p><strong><em>Casey Setash, Colorado State University</em></strong></p>
<h2>Abundant uncertainty</h2>
<p>Ecologists <a href="https://scholar.google.com/citations?user=KRhLLdAAAAAJ&hl=en">like me</a> often measure a field season by the numbers: 40 birds captured, 85 nest plots searched, three times when the truck got stuck. This year we’re thinking about Colorado’s coronavirus case count.</p>
<p>My field site sits at an elevation of about 8,500 feet in northern Colorado’s Jackson County. The landscape and lifestyles here have remained largely unchanged over the last century. Jackson is also one of the few counties in Colorado without a positive case of COVID-19. </p>
<p>I’m conducting field work that will inform my dissertation on waterfowl breeding in flood-irrigated agricultural systems, as well as a long-term waterfowl monitoring project run by <a href="https://cpw.state.co.us/">Colorado Parks and Wildlife</a>. Answering my proposed questions requires capturing 40 female <a href="https://www.allaboutbirds.org/guide/mallard">mallards</a> and <a href="https://www.allaboutbirds.org/guide/Gadwall/id">gadwall</a>, two common duck species. We mark them with GPS transmitters, conduct biweekly samples in the flooded fields for invertebrates – small crustaceans that ducks eat – and carry out daily nest searches within a 250-square-mile area. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=832&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=832&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=832&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1046&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1046&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334389/original/file-20200512-82370-1avjixj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1046&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dawn at Casey Setash’s research site in northern Colorado.</span>
<span class="attribution"><span class="source">Casey Setash</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The 2020 field season is the second of three field seasons that I will conduct for my Ph.D., and I had plans to hit the ground running. Instead, we have whittled our six-person crew down to three and are living in trailers without running water, rather than in U.S. Forest Service housing that normally would be available.</p>
<p>Our daily routine of cold mornings counting ducks, checking traps and searching for nests feels familiar and comforting. But every task is tinged with worry and guilt. What if we introduce COVID-19 to Jackson County? How are we going to attach GPS transmitters to ducks – a process that usually takes at least two people – while maintaining proper social distancing measures? Scientists are used to estimating uncertainty, but almost everything this year is a question mark. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=874&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=874&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=874&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1098&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1098&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334392/original/file-20200512-82366-12aoa4f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1098&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Colorado Parks & Wildlife technician Ella Engelhard with a tagged gadwall.</span>
<span class="attribution"><span class="source">Casey Setash</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Waterfowl ecologists were among the first scientists to initiate <a href="https://www.fws.gov/birds/surveys-and-data/population-surveys.php">long-term ecological monitoring</a> in the 1950s. Today, states still base decisions about hunting limits on annual surveys of ducks breeding throughout the <a href="https://www.ducks.org/conservation/where-ducks-unlimited-works/prairie-pothole-region">Prairie Pothole Region</a> of the northern Great Plains, also known as the <a href="https://www.fws.gov/prairiesconservation/pdfs/PrairiesConservation_infographic_031814_Updated.pdf">duck factory of North America</a>. </p>
<p>Long-term projects like these often are replacement data sources when studies like mine go awry. But this year, for the first time since 1955, neither the <a href="https://fws.gov/">U.S. Fish and Wildlife Service</a> nor the <a href="https://en.wikipedia.org/wiki/Canadian_Wildlife_Service">Canadian Wildlife Service</a> will carry out their Waterfowl Breeding Population and Habitat Survey. </p>
<p>While safety precautions are changing everything, from the amount of data we can collect to the social structure of our field crew, I am one of the lucky few who get to keep working. My field site lies in a sweet spot, between “too far from a hospital” and “too many people.” And it is comforting to be outside with some semblance of normalcy, rather than sitting indoors wondering what the ducks are up to.</p>
<p>[<em>The Conversation’s newsletter explains what’s going on with the coronavirus pandemic. <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-daily">Subscribe now</a>.</em>]</p><img src="https://counter.theconversation.com/content/137045/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The COVID-19 pandemic is interrupting scientific field work across North America, leaving blank spots in important data sets and making it harder to track ecological change.Richard B. Primack, Professor of Biology, Boston UniversityCasey Setash, PhD student in Fish, Wildlife, and Conservation Biology, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1299672020-03-04T11:59:16Z2020-03-04T11:59:16ZSpring is arriving earlier across the US, and that’s not always good news<figure><img src="https://images.theconversation.com/files/316566/original/file-20200221-92512-169j38o.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1599%2C1200&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Yellow trout lily flowers nearly a week earlier now than in previous decades in the Appalachian Mountains.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Yellow_Trout_Lily_-_Flickr_-_treegrow_(2).jpg">Katja Schulz/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Across much of the United States, a warming climate has advanced the arrival of spring. This year is no exception. In parts of the Southeast, spring has arrived <a href="https://www.usanpn.org/news/spring">weeks earlier than normal</a> and may turn out to be the <a href="https://weather.com/news/weather/news/2020-02-28-warm-winter-2019-20-what-does-that-mean-spring-2020-temperature">warmest spring on record</a>. </p>
<p>Apple blossoms in March and an earlier start to picnic season may seem harmless and even welcome. But the early arrival of springtime warmth has many downsides for the natural world and for humans.</p>
<p>Rising temperatures in the springtime <a href="http://www.nurserycropscience.info/ipm/scouting-monitoring/technical-pubs/herms-2004-using-degree-days-plant-phenology-to.pdf">signal plants and animals to come alive</a>. Across the United States and worldwide, climate change is <a href="https://doi.org/10.1038/s41558-018-0067-3">steadily disrupting</a> the arrival and interactions of leaf buds, cherry blossoms, insects and more.</p>
<p>In my work as a <a href="https://scholar.google.com/citations?user=3FUDzuIAAAAJ&hl=en&oi=ao">plant ecologist</a> and director of the <a href="http://www.usanpn.org">USA National Phenology Network</a>, I coordinate efforts to track the timing of seasonal events in plants and animals. Dramatically earlier spring activity has been documented in <a href="https://doi.org/10.1111/j.1365-2486.2007.01404.x">hundreds of species</a> around the globe. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/wsSoqcVAhpo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Phenology is the study of the timing of life cycle events, such as plant flowering and animal migrations. Resource managers and citizen scientists are studying phenological events in Great Smoky Mountains National Park.</span></figcaption>
</figure>
<h2>Lilies, blueberries, birds and more … all sped up</h2>
<p>Records managed by the USA National Phenology Network and other organizations prove that spring has accelerated over the long term. For example, the common yellow trout lily <a href="https://doi.org/10.1007/s11258-019-00956-7">blooms nearly a week earlier</a> in the Appalachian Mountain region than it did 100 years ago. Blueberries in Massachusetts <a href="https://www.wbur.org/news/2017/07/12/studying-climate-change-walden-pond">flower three to four weeks earlier</a> than in the mid-1800s. And over a recent 12-year period, over half of 48 migratory bird species studied <a href="https://doi.org/10.1038/s41598-017-02045-z">arrived at their breeding grounds up to nine days earlier</a> than previously.</p>
<p>Warmer spring temperatures have also led <a href="https://doi.org/10.1111/1365-2656.12452">beetles, moths</a> and <a href="https://doi.org/10.1111/gcb.12920">butterflies</a> to emerge earlier than in recent years. Similarly, hibernating species like <a href="https://doi.org/10.1038/srep11580">frogs</a> and <a href="https://www.nationalgeographic.com/news/2015/04/150413-utah-bears-hibernation-warm-winter-climate-science/">bears</a> emerge from hibernation earlier in warm springs. </p>
<p>All species don’t respond to warming the same way. When species that depend on one another — such as pollinating insects and plants seeking pollination - don’t respond similarly to changing conditions, populations suffer. </p>
<p>In Japan, the spring-flowering ephemeral <em>Corydalis ambigua</em> <a href="https://doi.org/10.1890/12-2003.1">produces fewer seeds</a> than in previous decades because it now flowers earlier than when bumblebees, its primary pollinators, are active. Similarly, populations of pied flycatchers – long-distance migrating birds that still arrive at their breeding grounds at the regular time – are <a href="https://doi.org/10.1038/nature04539">declining steeply</a>, because populations of caterpillars that the flycatchers eat now peak prior to the birds’ arrival.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=431&fit=crop&dpr=1 600w, https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=431&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=431&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/312904/original/file-20200130-41527-14d7uay.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This map shows when enough springtime warmth had accumulated to initiate springtime activity in early-season plants in 2019.</span>
<span class="attribution"><span class="source">USA National Phenology Network</span></span>
</figcaption>
</figure>
<h2>Warmth followed by frost can kill</h2>
<p>Earlier springs can devastate valuable farm crops. Cherry, peach, pear, apple and plum trees blossom during early warm spells. Subsequent frost can kill the blooms, which means the trees will not produce fruit. </p>
<p>In March 2012, Michigan cherry blossoms opened early after temperatures climbed into the 80s. Then at least 15 frosts from late March through May <a href="https://www.pbs.org/newshour/science/science-july-dec12-michigancherry_08-15">destroyed 90% of the crop</a>, causing US$200 million in damages. And in 2017, after Georgia peach trees flowered during an extremely early warm spell, frost killed <a href="https://www.ajc.com/news/state--regional-govt--politics/georgia-peach-crop-decimated-after-warm-winter/3SFVEukXWLLJB0zSox9i4M/">up to 80% of the crop</a>. </p>
<p>Early springs also affect ornamental plants and gardens. They hasten <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212010">allergy symptoms</a> and the appearance of <a href="http://www.totallandscapecare.com/green-industry-news/phenology-maps/">turf pests</a>. Popular species like tulips open up sooner than they used to a decade or more ago. In recent years, tulips have bloomed before “tulip time” festivals in <a href="https://whotv.com/2019/04/26/tulips-in-bloom-in-pella-ahead-of-annual-celebrations/">Iowa</a>, <a href="https://www.oregonlive.com/travel/2016/02/tulip_festival_expected_to_blo.html">Oregon</a> and <a href="https://www.michiganradio.org/post/blossoms-ahead-schedule-holland-s-tulip-time-festival">Michigan</a>.</p>
<p>Cherry trees around Washington D.C.’s Tidal Basin bloom at <a href="https://www.nps.gov/subjects/cherryblossom/bloom-watch.htm">dramatically different times from year to year</a>. They are expected to bloom <a href="https://doi.org/10.1371/journal.pone.0027439">weeks in advance</a> of the National Cherry Blossom Festival in the coming decades.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1227703051814875141"}"></div></p>
<h2>Springtime shifts by region</h2>
<p>The start of spring isn’t advancing at the same rate across the United States. In <a href="https://doi.org/10.1029/2019GL085251">a recent study</a> with <a href="https://scholar.google.com/citations?user=A74aBb8AAAAJ&hl=en&oi=ao">climatologist Michael Crimmins</a>, I evaluated changes in the arrival of springtime warmth over the past 70 years. </p>
<p>We found that in the Northeast, warmth associated with the leading edge of springtime activity has advanced by about six days over the past 70 years. In the Southwest, the advancement has been approximately 19 days. Spring is also arriving significantly earlier in the Southern Rockies and the Pacific Northwest. In contrast, in the Southeast the timing of spring has changed little.</p>
<p><iframe id="PQjEF" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/PQjEF/4/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Although the trend over decades toward earlier springs is clear, weather patterns unfolding across the continent can vary the start of the season dramatically from year to year at any one spot. The <a href="http://www.usanpn.org">USA National Phenology Network</a> produces maps that document the onset of biological activity over the course of the spring season. </p>
<p>The network also maintains a <a href="https://www.usanpn.org/news/spring">live map</a> showing where spring has arrived. In some parts of the Southeast, spring 2020 has been the earliest in decades.</p>
<h2>Help scientists document change</h2>
<p>While numerous studies have documented clear changes in the timing of activity in certain plants and animals, scientists have little to no information on the cycles of most of the millions of species on Earth. Nor do they know the consequences of such changes yet.</p>
<p>One important way to fill knowledge gaps is documenting what’s happening on the ground. The USA National Phenology Network runs a program called <a href="http://www.naturesnotebook.org">Nature’s Notebook</a> suited for people of nearly all ages and skill levels to track seasonal activity in plants and animals. Since the program’s inception in 2009, participants have contributed more than 20 million records. </p>
<p>These data have been used in over <a href="https://www.usanpn.org/publications">80 studies</a>, and we are looking for more observations from the public that can help scientists understand what causes nature’s timing to change, and what the consequences are. We welcome new volunteers who can help us unravel these mysteries.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.] </p>
<p><em>This article has been updated to reflect that blueberries in Massachusetts are now flowering three to four weeks earlier than they did in the mid-1800s.</em></p><img src="https://counter.theconversation.com/content/129967/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The University of Arizona receives funding from the U.S. Geological Survey, the U.S. Fish & Wildlife Service, the National Science Foundation, and the National Aeronautics and Space Administration to fund the USA National Phenology Network.</span></em></p>Climate change has advanced the arrival of spring by as much as several weeks in some parts of the US. This can mean major crop losses and disconnects between species that need each other to thrive.Theresa Crimmins, Director, USA National Phenology Network, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1267112019-11-15T13:29:11Z2019-11-15T13:29:11ZTons of acorns? It must be a mast year<figure><img src="https://images.theconversation.com/files/301775/original/file-20191114-26237-144yg3h.jpg?ixlib=rb-1.1.0&rect=203%2C0%2C3962%2C2605&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A mast year can be a squirrel's dream come true.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/acorns-fruits-closeup-oak-nut-tree-1060538540">Editor77/Shutterstock.com</a></span></figcaption></figure><p>If you have oak trees in your neighborhood, perhaps you’ve noticed that <a href="https://doi.org/10.1111/j.0030-1299.2004.12722.x">some years the ground is carpeted</a> with their acorns, and some years there are hardly any. Biologists call this pattern, in which all the oak trees for miles around make either lots of acorns or almost none, “masting.” </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301776/original/file-20191114-26202-8v7s3l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A dipterocarp seed.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hand-holding-dipterocarp-seed-1368795053">kumakumalatte/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Naturalists have <a href="https://www.npr.org/2023/11/04/1210645279/hardwood-trees-are-dropping-more-nuts-than-usual-this-fall">declared this fall a mast year for many trees</a>: Not just oaks, but walnuts, beeches and more are all making tons of nuts all at the same time.</p>
<p>Many other types of trees, from familiar North American species such as pines and hickories to the massive dipterocarps of Southeast Asian rainforests, show similar synchronization in seed production. But why and how do trees do it?</p>
<h2>Benefits of synchronized seeds</h2>
<p>Every seed contains a packet of energy-rich starch to feed the baby tree that lies dormant inside. This makes them a tasty prize for all sorts of animals, from beetles to squirrels to wild boar.</p>
<p>If trees coordinate their seed production, these seed-eating animals are <a href="https://doi.org/10.1016/S0378-1127(03)00157-9">likely to get full</a> long before they eat all the seeds produced in a mast year, leaving the rest to sprout.</p>
<p>For trees such as oaks that depend on having their seeds carried away from the parent tree and buried by animals like squirrels, a mast year has an extra benefit. When there are lots of nuts, <a href="https://doi.org/10.1007/BF02857850">squirrels bury more of them</a> instead of eating them immediately, spreading oaks across the landscape. </p>
<h2>Getting in sync</h2>
<p>It’s still something of a mystery how trees synchronize their seed production to get these benefits, but several elements seem to be important.</p>
<p>First, producing a big crop of seeds <a href="https://doi.org/10.1111/nph.14114">takes a lot of energy</a>. Trees make their food through <a href="https://www.livescience.com/51720-photosynthesis.html">photosynthesis</a>: using energy from the Sun to turn carbon dioxide into sugars and starch. There are only so many resources to go around, though. Once trees make a big batch of seeds, they may need to switch back to making new leaves and wood for a while, or take a year or two to replenish stored starches, before another mast. </p>
<p>But how do individual trees decide when that mast year should be? <a href="https://doi.org/10.1890/14-0819.1">Weather conditions appear to be important</a>, especially spring weather. If there’s a cold snap that freezes the flowers of the tree – and yes, oaks do have flowers, they’re just extremely small – then the tree can’t produce many seeds the following fall.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301777/original/file-20191114-26217-1gjk78k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Harm to the tree’s flowers in spring doesn’t bode well for the acorn crop come fall.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/detail-flowering-oak-spring-close-165059594">almgren/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>A <a href="https://doi.org/10.1890/07-0217.1">drought during the summer</a> could also kill developing seeds. Trees will often shut the pores in their leaves to save water, which also reduces their ability to take in carbon dioxide for photosynthesis.</p>
<p>Because all the trees within a local area are experiencing essentially the same weather, these environmental cues can help coordinate their seed production, acting like a reset button they’ve all pushed at the same time.</p>
<p>A third intriguing possibility that researchers are still investigating is that trees are “talking” to each other via chemical signals. Scientists know that when a plant is damaged by insects, it often <a href="https://doi.org/10.1042/bst0310123">releases chemicals into the air that signal</a> to its other branches and to neighboring plants that they should turn on their defenses. Similar signals could potentially help trees coordinate seed production. </p>
<p>Investigation of tree-to-tree communication is still in its infancy, however. For instance, ecologists recently found that <a href="https://doi.org/10.4161/psb.28258">chemicals released from the roots</a> of the leafy vegetable mizuna can affect the flowering time of neighboring plants. While this sort of communication is unlikely to account for the rough synchronization of seed production over dozens or even hundreds of miles, it could be important for syncing up a local area.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301778/original/file-20191114-26202-1x6ie87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lots of nuts is good news for the animals that eat them – and the bigger animals that, in turn, eat them.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/squirrel-autumn-acorn-dry-leaves-128704667">TessarTheTegu/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Masting’s effects ripple through the food web</h2>
<p>Whatever the causes, masting has consequences that flow up and down the food chain.</p>
<p>For instance, rodent populations often boom in response to high seed production. This in turn results in more food for rodent-eating predators like hawks and foxes; <a href="https://doi.org/10.1007/s00442-007-0859-z">lower nesting success for songbirds</a>, if rodents eat their eggs; and potentially higher risk of transmission of diseases <a href="https://doi.org/10.1186/1476-072X-8-1">like hantavirus to people</a>.</p>
<p>If the low seed year that follows causes the rodent population to collapse, the effects are reversed.</p>
<p>The seeds of masting trees have also historically been important for feeding human populations, either directly or as food for livestock. Acorns were a staple in the diet of Native Americans in California, with families carefully <a href="https://heydaybooks.com/book/the-way-we-lived/">tending particular oaks and storing the nuts</a> for winter. In Spain, the most prized form of ham still comes from <a href="http://www.mast-producing-trees.org/2009/11/acorn-finished-pork-an-ancient-tradition/">pigs that roam through the oak forests</a>, eating up to 20 pounds of acorns each day.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301779/original/file-20191114-26202-1gg10ot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sometimes the ground seems paved in acorns.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/acorns-on-ground-1243010128">kurutanx/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>So the next time you take an autumn walk, check out the ground under your local oak tree – you might just see the evidence of this amazing process.</p><img src="https://counter.theconversation.com/content/126711/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Moran does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Masting is what biologists call the pattern of trees for miles around synchronizing to all produce lots of seeds − or very few. Why and how do they get on schedule?Emily Moran, Assistant Professor of Life and Environmental Sciences, University of California, MercedLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1258292019-10-25T15:05:51Z2019-10-25T15:05:51ZClimate change is forcing butterflies and moths to adapt – but some species can’t<figure><img src="https://images.theconversation.com/files/298581/original/file-20191024-170462-1oy8c9n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The silver-studded blue butterfly is among that species that may be flexible enough to thrive.</span> <span class="attribution"><span class="source">Callum Macgregor</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Butterflies are rather like Goldilocks, preferring conditions to be neither too hot nor too cold, but “just right”. Under climate change, the temperature at any given time of summer is, on average, getting warmer, leaving butterflies (and their nocturnal cousins, the moths) with the challenge of how to remain in their optimal temperature window.</p>
<p>One of the main ways in which species are achieving this is by changing the time of year at which they are active. Scientists refer to the timing of such lifecycle events as “<a href="https://www.ceh.ac.uk/news-and-media/news/feature-why-should-we-care-about-phenology">phenology</a>”, so when an animal or plant starts to do things earlier in the year it is said to be “advancing its phenology”. </p>
<p>These advances have <a href="https://thinkprogress.org/climate-change-is-messing-up-butterflys-flight-seasons-8dc2bf367a26/">been observed</a> already in a wide range of butterflies and moths – indeed, most species are advancing their phenology to some extent. In Britain, as the average spring temperature has increased by roughly 0.5°C over the past 20 years, species have advanced by between three days and a week on average, to keep track of cooler temperatures. </p>
<p>Is this a sign that butterflies and moths are well equipped to cope with climate change, and readily adjust to new temperatures? Or are these populations under stress, being dragged along unwillingly by unnaturally fast changes?</p>
<p>In a new study published in <a href="https://www.nature.com/articles/s41467-019-12479-w">Nature Communications</a>, colleagues and I sought to answer this question. We first pulled together data from millions of records submitted by butterfly and moth enthusiasts to one of four recording schemes run by <a href="https://butterfly-conservation.org/">charities</a> or <a href="https://www.ceh.ac.uk/">research</a> <a href="https://www.rothamsted.ac.uk/insect-survey">institutes</a>. This gave us information on 130 species of butterflies and moths in Great Britain every year for a 20-year period between 1995 and 2014. We could then estimate the abundance and distribution of each species across this time, along with how far north they had moved. The data also, crucially, allowed us to estimate subtle changes in what time of the year each species was emerging from the chrysalis as a fully-grown butterfly. </p>
<h2>It pays to reproduce quickly</h2>
<p>Analysing the trends in each variable, we discovered that species with more flexible lifecycles were more likely to be able to benefit from an earlier emergence driven by climate change. Some species are able to go from caterpillar to butterfly twice or more per year, so that the individual butterflies you see flying in the spring are the grandchildren or great-grandchildren of the individuals seen a year previously. </p>
<p>Among these species, we observed that those which have been advancing their phenology the most over the 20-year study period also had the most positive trends in abundance, distribution and northwards extent. For these species – such as Britain’s tiniest butterfly, the dainty <a href="https://www.ukbutterflies.co.uk/species.php?species=minimus">small blue</a> – emerging early in spring gives more time for their later-summer generations to complete their reproductive cycles before the arrival of autumn, allowing more population growth to occur.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298578/original/file-20191024-170458-1q0kelq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Small blue: Britain’s tiniest butterfly.</span>
<span class="attribution"><span class="source">Callum Macgregor</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Other species, however, are less flexible and restricted to a single reproductive cycle per year. For these species, we found no evidence of any benefit to emerging earlier. Indeed, worryingly, we found that the species in this group that specialise in one very specific habitat type (often related to the caterpillar’s preferred diet) actually tended to most harmed by advancing phenology. </p>
<p>The beautiful <a href="https://butterfly-conservation.org/our-work/conservation-projects/conserving-the-high-brown-fritillary">high brown fritillary</a>, often described as Britain’s most endangered butterfly, fits this category perfectly. It is found only alongside the dog-violets that its caterpillar eats, in coppiced woodland and limestone pavement habitats. It’s also a single-generation butterfly that has advanced its phenology. This suggests that climate change, while undoubtedly not the sole cause, might have played a part in the downfall of this species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298575/original/file-20191024-170458-1jv2zrl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The high brown fritillary was once widespread, but is now found in just a few sites in Lancashire and the south-west.</span>
<span class="attribution"><span class="source">Callum Macgregor</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>All is not lost, however. Many of Britain’s single-generation species show the capacity, in continental Europe, to add a second generation in years that are sufficiently warm. Therefore, as the climate continues to warm, species like the <a href="https://butterfly-conservation.org/butterflies/silver-studded-blue">silver-studded blue</a> might be able to switch to multiple generations in the UK as well, and thereby begin to extract benefits from the additional warmth, potentially leading to population increases.</p>
<h2>Specialists are at risk</h2>
<p>More immediately, we can arm ourselves with this knowledge to spot the warning signs of species that may be most at risk. Clearly the single-generation habitat specialists are of particular concern, as many are already endangered or vulnerable – not just the high brown fritillary and silver-studded blue, but also species such as pearl-bordered fritillary, grizzled skipper and the particularly sought-after <a href="https://butterfly-conservation.org/butterflies/white-admiral">white admiral</a> of southern England. Multi-generation species that are failing to advance their phenology might also be threatened: into this category falls another of Britain’s most sharply-declining butterflies: the wall brown.</p>
<p>Using this knowledge to help protect moths and butterflies from climate change is not simply important for the sake of the butterflies and moths themselves – these species also play a number of important roles in our ecosystems. Their caterpillars consume vast quantities of plant material, and in turn act as prey for <a href="https://theconversation.com/coming-out-of-the-closet-why-i-will-always-love-moths-35590">birds, bats, and other small mammals</a>, while moths even act as pollinators of a surprisingly wide range of plant species, <a href="https://butterfly-conservation.org/news-and-blog/the-nocturnal-pollinators-scientists-reveal-the-secret-life-of-moths">possibly including some important crops</a>. </p>
<p>According to <a href="https://jncc.gov.uk/news/latest-butterfly-official-statistics/">Butterfly Conservation</a>, around two-thirds of butterfly species have declined in the UK over the past 40 years. If this trend continues, it might have unpredictable knock-on effects for other species in the ecosystem. Only by arming ourselves with an understanding of why butterfly numbers are down can we hope to halt or reverse the decline. </p>
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<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1125829">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/125829/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Callum Macgregor receives funding from the Natural Environment Research Council (grant ID: NE/N015797/1). He has formerly received funding from, collaborates with, and volunteers for the charity Butterfly Conservation.</span></em></p>We looked at 130 species to see which will be the winners and losers from global warmingCallum Macgregor, Postdoctoral Research Associate, University of YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1249782019-10-24T11:49:14Z2019-10-24T11:49:14ZLeaf peep for science – I want your old photos of fall foliage<figure><img src="https://images.theconversation.com/files/298412/original/file-20191023-119433-8lq1kf.jpg?ixlib=rb-1.1.0&rect=1101%2C437%2C5393%2C3303&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What can your vacation pix tell scientists?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/female-hiker-standing-on-ledge-enjoying-1463849003">Try Media/Shutterstock.com</a></span></figcaption></figure><p>Every October, when I was growing up in Massachusetts, my parents would check out the fall foliage reports and determine where we were going to drive to see the colorful leaves. And they still do. In New England, leaf peeping, as it’s called, is a <a href="https://www.pri.org/stories/2018-10-19/leaf-peeping-huge-new-england-will-climate-change-alter-tourism">billion dollar industry</a> and millions of people travel to the region during foliage season. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/B3uqR3qJDEq","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>In Maine’s Acadia National Park, visitation has <a href="https://irma.nps.gov/Stats/">more than doubled in September and October</a> since the early 1990s. Tourists book leaf peeping cruises, bus trips and lodging packages, all scheduled to coincide with what’s traditionally been the somewhat predictable fall foliage season.</p>
<p>But Earth’s climate is changing. A big question is <a href="https://doi.org/10.1371/journal.pone.0057373">how climate change’s impacts</a> <a href="https://theconversation.com/fall-foliage-in-the-crosshairs-of-climate-change-32012">on the timing, duration and vibrancy</a> <a href="https://doi.org/10.2737/NRS-GTR-99">of fall foliage</a> will affect the tourist season.</p>
<h2>Pulling together all kinds of data</h2>
<p>Untangling the relationship between climate, fall foliage and visitorship in Acadia National Park – <a href="http://www.stephaniespera.com/anpfallfoliage.html">the goal of my research</a> – requires a variety of data, including meteorological observations, park visitor surveys and knowledge of when fall foliage starts, peaks and ends every year.</p>
<p><a href="https://scholar.google.com/citations?user=cG3piHgAAAAJ&hl=en&oi=ao">As an environmental scientist</a>, one of the primary ways I study changes in vegetation phenology – that is, the timing of biological events like flowering, leaf out, or onset and duration of fall foliage – is through the use of satellite data. Every day, <a href="https://neo.sci.gsfc.nasa.gov/">dozens of satellites</a> circle the Earth collecting data on everything from land cover to weather to sea surface temperatures to ground water to the chemical composition of the atmosphere. </p>
<p>These data are crucial in teasing apart environmental changes. Scientists have used satellite data of land cover and vegetation to show that as global temperatures increase, <a href="https://doi.org/10.1016/j.tree.2007.04.003">trees are flowering earlier</a> and <a href="https://doi.org/10.1029/2012JG001977">earlier</a>.</p>
<p>But like all technology, the farther back in time you go, the lower the quality of the data. Even worse, there isn’t any reliable satellite data over Acadia National Park before the year 2000 at all. So my team needs to get creative.</p>
<h2>Science behind the seasonal display</h2>
<p>Here’s what biologists do know. As summer turns to autumn, the days get shorter and colder, both of which are signals to trees to stop <a href="https://harvardforest.fas.harvard.edu/autumn-foliage-color">photosynthesizing</a> and producing the chlorophyll that makes their leaves green. With green chlorophyll out of the picture, the orange and yellow carotenoid pigments in the leaves that are masked by all the chlorophyll production all summer have <a href="https://doi.org/10.1038/news.2007.202">their moment to shine</a>.</p>
<p>In some trees, cooler weather cues the production of a chemical called anthocyanin, which helps trees pull the nutrients from their leaves into their trunk and roots. Anthocyanin is responsible for those gorgeous red and purple leaves on trees like red maples and <a href="https://www.americanforests.org/blog/science-behind-fall-foliage/">dogwoods</a>. </p>
<p>While every tree is different, studies have found that <a href="https://doi.org/10.1038/nplants.2016.133">earlier spring bud burst</a>, warmer temperatures and a dry fall are linked to a <a href="https://doi.org/10.1073/pnas.1509991112">later fall foliage season</a>. A <a href="https://doi.org/10.1016/j.agrformet.2017.12.259">shorter foliage season</a> can result from a hot summer and wet fall. Additionally, the concentration of nitrogen in the atmosphere – which humans are releasing into the atmosphere on faster time scales than nature does – affects just how red those <a href="https://academic.oup.com/treephys/article/23/5/325/1657937">gorgeous maples get</a>.</p>
<p>The northeastern U.S. has gotten <a href="https://doi.org/10.1371/journal.pone.0101302">warmer</a> and <a href="https://doi.org/10.1175/JHM-D-16-0195.1">wetter</a> over the last century. How have these climate changes affected the timing, vibrancy and duration of fall foliage in Acadia National Park? Have tourists, in turn, changed how and when they visit the park?</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/B2ce1DTBECS","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Looking in new places for old foliage records</h2>
<p>To answer this question, my team is using historical data on temperature and precipitation in Acadia National Park. What we’re missing, though, is information about when fall foliage has started and peaked, going back through the decades. </p>
<p>Most historical records of phenology, like those of <a href="https://doi.org/10.1016/j.biocon.2008.10.038">Henry David Thoreau</a>, are focused on the spring season. Historical documentation of fall foliage is harder to come by.</p>
<p>My colleagues and I are mining National Park reports and old newspapers, like this article in the Oct. 12, 1893 Bar Harbor Times, which is local to Acadia National Park:</p>
<blockquote>
<p>“The autumn foliage on Mount Desert was never more brilliant than this year. The hills are ablaze with crimson and yellow, and the woodbine embowered cottages are resplendent with opalescent tints. But, alas ‘tis but the beetie glow in the consumptive’s cheek. A few weeks and winter’s white pail will cover all the autumn glories.”</p>
</blockquote>
<p>But the records are few and far between.</p>
<p>We’ve found one continuous record of fall foliage since 1975, although it’s not focused on the Acadia area. <a href="https://pollyspancakeparlor.com/wp-content/uploads/Leaf-Chart-1-1.pdf">Polly’s Pancake Parlor</a> in Sugar Hill, New Hampshire has been collecting data on onset and peak of fall foliage since the mid-1970s. Interestingly, their data show that since 1975 fall foliage gets going earlier in the year, but peak fall foliage occurs later.</p>
<h2>Maybe you have the selfies we seek</h2>
<p>This lack of data is why we need citizen scientists to help us fill in the gaps. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/B2y6pisBpgH","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>With apps and programs like <a href="https://www.usanpn.org/natures_notebook">Nature’s Notebook</a>, <a href="https://www.inaturalist.org/">iNaturalist</a>, <a href="https://budburst.org/">BudBurst</a> and <a href="https://ebird.org/home">eBird</a>, it’s never been easier for anyone to share their observations of the world around them. Scientists have recently been trawling social media sites like Twitter, Flickr and Instagram for data to <a href="https://doi.org/10.1038/srep02976">estimate park visitation rates</a>, <a href="https://doi.org/10.1016/j.ecoinf.2014.08.008">map monarch butterfly and snowy owl sightings</a> and understand the various ways people <a href="https://doi.org/10.1073/pnas.1614158113">value different landscapes</a>. </p>
<p>Collecting photos from people who’ve traveled to Acadia is helping us validate the satellite data we do have. My team is able to make sure what we see in the satellite images actually represents of what is happening on the ground in the park. We are so appreciative of all the <a href="https://www.instagram.com/p/B3aO1trhMmg/">photos</a> we’ve received from people who have visited Acadia this year. And we have received a bunch, 907 to be exact, of submitted photos from the <a href="https://www.instagram.com/p/B2EzlCLBtWX/">post-cellphone camera era</a>.</p>
<p>That doesn’t get us back to before the advent of continuous satellite data, though. We need leaf peepers to dig deeper into their personal photo albums to help us figure out the timing of fall foliage before the year 2000.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/B3PO8TzBp3-","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Those earlier photos – from a time of yore when you actually had to remove film from a camera and take it to get developed – are proving much harder to come by. So far we have two data points from before 2010, one from <a href="https://www.instagram.com/p/B2RdMktBGzW/">1987</a> and one from <a href="https://www.instagram.com/p/B2ce1DTBECS/">1981</a>.</p>
<p>We’re <a href="http://www.stephaniespera.com/anpfallfoliage.html">asking for your help</a>. We know those awkward family photos of you or your parents in their 1970s bell bottoms standing in front of Acadia’s Jordan Pond exist. And we want them. If you have any old vacation photos taken in the park during the fall, scan them and <a href="mailto:anpfallfoliage@richmond.edu">send them our way</a>.</p>
<p>Understanding the relationships between climate change, fall foliage and park visitorship have important implications for park management, the local economies of towns on and around Mount Desert Island, and those of us who love visiting Acadia in the fall. So leaf peep – for science.</p>
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<p><a href="http://www.aag.org">Stephanie Spera is a member of the American Association of Geographers. </a></p>
<footer>The association is a funding partner of The Conversation US.</footer>
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</p><img src="https://counter.theconversation.com/content/124978/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephanie Spera receives funding for this project from from the Second Century Stewardship, a collaboration between the Schoodic Institute, National Park Service and the National Park Foundation.</span></em></p>To untangle the relationship between climate change, fall foliage and national park visitors, researchers are asking tourists to check their old photo albums for snapshots that could hold valuable data.Stephanie Spera, Assistant Professor of Climate Change & Remote Sensing, University of RichmondLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1237832019-09-24T12:58:18Z2019-09-24T12:58:18ZExplainer: why phenology is key in tracking climate change<figure><img src="https://images.theconversation.com/files/293397/original/file-20190920-135113-m2otyv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The longest phenological record derive from the cherry blossoms in Japan. </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Phenology is the timing of annually recurrent <a href="https://journals.sagepub.com/doi/full/10.1177/0309133315578940">biological events</a>. These include the timing of spring blossoming, fruit development in summer and leaf colouration in autumn. In animals it can include the timing of migration, hibernation, hatching, and mating. </p>
<p>The timing of these phenological events is <a href="https://www.sciencedirect.com/science/article/pii/S0168192312002869">controlled</a> by climate. </p>
<p>The longest phenological record derives from the Japanese cherry festival, dating back to the <a href="https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.1594">ninth century</a>. The date of flowering, and hence the timing of the festival, has been affected over the centuries by changes in spring temperatures. </p>
<p>In the United Kingdom, the <a href="https://www.jstor.org/stable/2261570?seq=1#metadata_info_tab_contents">Marsham record</a> comprises two centuries of phenological records captured by generations of the Marsham family, which scientists found captured advances in phenological events driven by changes in temperature and rainfall. </p>
<p>A paper written eight years ago in South Africa showed how apple and pear trees in the southwestern Cape were <a href="https://www.sciencedirect.com/science/article/pii/S0168192310002893">flowering earlier</a> due to changes in temperature.</p>
<p>These changes in the timing of phenological events are important to monitor. Phenology is <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ele.12135">argued</a> to be one of the most sensitive biological indicators of climate change. Phenological shifts are often <a href="https://link.springer.com/content/pdf/10.1023/A:1016125215496.pdf">detected</a> long before irreversible ecosystem responses are apparent. </p>
<p>In a <a href="https://journals.sagepub.com/doi/pdf/10.1177/0309133315578940">review paper</a>, we found that the volume of research on phenological responses to climate change increased significantly during the 1990s. This has <a href="https://journals.sagepub.com/doi/pdf/10.1177/0309133315578940">enabled scientists to compare</a> between study sites, species and different phenological events. </p>
<p>During this time, the methods used in monitoring and recording phenological changes expanded to include satellite remote sensing, digital repeat photography, phenological models and greenhouse experiments. Ground-based studies, which involve scientists or the public observing specific plants became widespread through citizen science projects such as the <a href="https://www.usanpn.org/usa-national-phenology-network">National Phenology Network</a>. This research remained, however, largely restricted to the northern hemisphere.</p>
<h2>How it works</h2>
<p>Depending on the species, phenological events are <a href="http://www.ssag.co.za/wp-content/uploads/2017/10/2018-Proceedings-of-the-Biennial-Conference-of-the-Society-of-South-African-Geographers.pdf">triggered</a> by the onset of rainfall, reaching a threshold temperature, the accumulation of heat above a certain threshold following winter, or the number of hours of sunshine, or even a combination of these. </p>
<p>As the climate is <a href="http://www.weathersa.co.za/Documents/Climate/SAWS_CC_REFERENCE_ATLAS_PAGES.pdf">changing</a> – with a progressive increase in temperature, changes in rainfall regimes, and heightened frequency of extreme events – these triggers are in many instances occurring earlier.</p>
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Read more:
<a href="https://theconversation.com/why-the-indian-ocean-is-spawning-strong-and-deadly-tropical-cyclones-116559">Why the Indian Ocean is spawning strong and deadly tropical cyclones</a>
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<p>Across the world in all classes of plants and animals, phenological shifts are <a href="https://www.nature.com/articles/nature01286">happening</a> because of these climatic changes that result from global warming. For most plants and animals, these phenological events are happening <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2486.2007.01404.x">earlier</a> each year. For some species, they’re are being <a href="https://www.sciencedirect.com/science/article/pii/S0168192314002019">delayed</a>. </p>
<p>This is because they are waiting on cooler, rather than warmer conditions, which are taking increasingly longer to occur, or are delayed by dormancy conditions not being <a href="https://www.nature.com/articles/s41558-018-0067-3">fulfilled</a>. This is what is happening to the sardine run along the <a href="https://theconversation.com/we-tracked-south-africas-sardine-run-over-66-years-heres-what-we-found-120369">KwaZulu-Natal coast</a>.</p>
<h2>Why it matters</h2>
<p>Phenological events are also often economically important. For example, changes in the timing of apple and pear flowering dates in the <a href="https://www.sciencedirect.com/science/article/pii/S0168192310002893">southwestern Cape</a> has important implications for the quality and quantity of the fruit yields. Shifts in the timing of the <a href="https://www.sajs.co.za/article/view/5887">sardine run</a> affects both fishing and tourism in Durban and surrounding towns. </p>
<p>This requires the public to be more aware of phenology. To think about how these shifts may affect their businesses, and to share records – whether diaries, photographs, logbooks or even oral histories – that capture these phenological events with scientists who can add them to a regional model to better forecast changes for unrecorded species and regions.</p><img src="https://counter.theconversation.com/content/123783/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Fitchett receives funding from the NRF-DST Centre of Excellence for Palaeoscience. </span></em></p>Monitoring the timing of recurring biological events is key to understanding the effects of climate change.Jennifer Fitchett, Senior Lecturer in Physical Geography, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1203692019-07-30T11:51:20Z2019-07-30T11:51:20ZWe tracked South Africa’s sardine run over 66 years: here’s what we found<figure><img src="https://images.theconversation.com/files/284689/original/file-20190718-116579-1pygnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>The <a href="https://www.shark.co.za/Pages/Sardinerun">sardine run</a> is well known among residents of the KwaZulu-Natal coastline that runs along South Africa’s east coast. Every year in winter, sardines migrate close to the shoreline. The event is well documented in the local press. </p>
<p>The sardine run is of great economic importance because it provides prime fishing opportunities and attracts large numbers of tourists who come for dolphin and shark sightings. Similar migration patterns are seen in <a href="https://www.sciencedirect.com/science/article/pii/S0079661111001418">Sweden</a>, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2419.2012.00632.x">Chile</a>, and the <a href="https://science.sciencemag.org/content/299/5604/217">Pacific Ocean</a>.</p>
<p>The sardine run is what scientists term a “phenological event” – a biological event that occurs at the same time every year. Phenological events are standard for plants and include the appearance of leaf and flower buds, blossoming, fruit development, fruit harvest and leaf colouration and fall. </p>
<p>For animals, the events are more varied and include hibernation, hatching, animal calls, moulting, and in the case of birds, game and fish (among others) migration.</p>
<p>Scientists have become very interested in phenology over the past few decades, because it’s one of the most sensitive biological indicators of climate change. As temperatures increase, the plants or animals experience their triggers for spring earlier and their triggers for winter later. As a result, many of these phenological events are occurring at different times of the year.</p>
<p>In a recently published <a href="https://doi.org/10.17159/sajs.2019/5887">paper</a> in the South African Journal of Science, we examined newspaper articles written between 1946 and 2012 that reported on the South African sardine run. From these articles we established an annual date of the peak of the sardine run. </p>
<p>We then explored how the dates of the sardine run have changed over the 65-year period, and statistically examined oceanographic and climatological factors to determine the cause of this change. We did this because there are very few phenological records for South Africa and consequently, the rate of phenological shifts and the associated climate signal is largely unknown. </p>
<p>Phenology is highly species and location <a href="https://journals.sagepub.com/doi/full/10.1177/0309133315578940">specific</a>, and so it’s important to reconstruct records for as many locations and as many plants and animals as possible. It’s also known that climate <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2005.3356">affects</a> the timing of phenological events globally, including <a href="https://www.nature.com/articles/nature02808">marine environments</a>. </p>
<p>Our research sought to determine changes in the pattern of the sardine run and, possibly, what might be behind them. The hope is that this can help fisheries plan for delays or failed migrations which are happening more <a href="https://www.dw.com/en/our-beautiful-planet-south-africas-sardine-run/a-44071241-0">frequently</a>. </p>
<h2>Nature’s biological clock</h2>
<p>Phenological shifts are specific to species and location. For example, Granny Smith apple trees are flowering approximately four days earlier for each 1°C increase in temperature in <a href="https://www.agriculturejournals.cz/publicFiles/49_2008-HORTSCI.pdf">Poland</a>. In <a href="https://www.sciencedirect.com/science/article/pii/S0168192310002893">South Africa</a>, these Granny Smith apples are flowering two days earlier for each 1°C increase in temperature.</p>
<p>For many species these events are happening earlier. This is because they are spring events and, under climate change, the temperatures that are perceived by plants and animals to be the onset of spring are occurring in late winter. For events that occur in autumn, the events are often occurring later, because the cooling that marks the start of winter has not yet occurred.</p>
<p>This is the case for the South African sardines. </p>
<p>We found that over the 66-year period, sardines arrived off the coast of Durban increasingly late – at a rate of 1.3 days later per decade. Over the six decades this has meant the date has changed from arrivals as early as mid-June at the beginning of the record to dates as late as mid-July in the last decade. </p>
<p>Through statistical analysis comparing the constructed phenological record with climate and ocean data, we hypothesise that the delay could be caused by two things. </p>
<p>First, the ocean water is warmer. Sardines can tolerate a maximum surface temperature of 21°C. But this temperature isn’t being reached consistently at the same time every year due to changes in ocean temperature.</p>
<p>The second factor is mid-latitude cyclones. There have been an increasing number of these in the east coast region. The relationship between them and the sardine run is complex and difficult to pin down. But this has also been <a href="https://www.ncbi.nlm.nih.gov/pubmed/28948709">recorded</a> for sardine migration in the North Pacific. </p>
<h2>Why it matters</h2>
<p>The delay is concerning. First, the large influx of sardines is important for the fishery industry. If the sardine run occurs at an unexpected time, or doesn’t occur at all, supply chains are disrupted and fishermen are placed at economic risk. </p>
<p>The unpredictability is also a problem for tourism. The sardine run attracts visitors who are keen on shark and dolphin sightings and may leave disappointed. </p>
<p>The delays in the sardine run also result in food shortages for predators such as sharks, which feed on the sardines. This is termed a species mismatch, and is increasingly observed as a result of climate change induced phenological shifts, where predators and their prey are no longer in the same place at the same time. This is because each species has its own unique trigger for a particular activity.</p><img src="https://counter.theconversation.com/content/120369/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Fitchett receives funding from the DST-NRF Centre of Excellence in Palaeoscience. </span></em></p><p class="fine-print"><em><span>Stefan Grab does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>South Africa’s annual sardine run is occurring increasingly late, and there have been instances where it doesn’t happen at all. Here’s why.Jennifer Fitchett, Senior Lecturer in Physical Geography, University of the WitwatersrandStefan Grab, Professor of Historical climate and weather, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1130012019-04-15T15:09:13Z2019-04-15T15:09:13ZAlberta grizzly bears will feel the effects of climate change<p>Toward the end of each summer, grizzly bears in Alberta’s Rocky Mountains gorge on the tart red berries of a shrub called Canada buffaloberry (<em><a href="http://mpgnorth.com/field-guide/elaeagnaceae/canada-buffaloberry">Shepherdia canadensis</a></em>). Lacking the salmon of coastal populations, the feast is the largest caloric event on an Alberta grizzly bear’s menu. This is the time when individuals gain much of the weight needed for hibernation.</p>
<p>But <a href="https://www.nature.com/articles/s41558-019-0454-4">our latest research</a>, published in the journal <em>Nature Climate Change</em>, shows that rising temperatures are advancing the development of plants like buffaloberry, pushing forward the timing of this annual buffet. </p>
<p>By the year 2080, buffaloberries in the Rockies will ripen nearly three weeks earlier than they presently do. We predict this change will alter the behaviour of the region’s grizzly bears, and perhaps threaten the reproductive rates of this vulnerable population. </p>
<h2>A new way to track plant development</h2>
<p>Our work is based on a horticultural principle well-known among Canadian gardeners: that plant development is tightly linked to temperature accumulation. A plant needs a certain amount of heat to proceed from one phenological stage to the next — from flowering to fruiting, for example. </p>
<p>We found that this principle can be applied at any spatial scale, from individual plants to entire landscapes. Based on this, we developed a novel strategy that uses thermal observations from satellite remote sensing to track the seasonal development of specific understory plants, like buffaloberry, across huge areas. </p>
<figure>
<iframe src="https://player.vimeo.com/video/326549287" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">This progression tracks Canada buffaloberry through a single growing season (April 30 to Oct. 7). The very brief ‘fully ripe fruit’ phenophase (seen here at the 14-second mark) is the only phenological stage of significant nutritional value to grizzly bears, highlighting the punctuated nature of this critical food resource.</span></figcaption>
</figure>
<h2>Ecological response to climate change</h2>
<p>The <a href="https://www.ipcc.ch/sr15/">Intergovernmental Panel on Climate Change (IPCC) reports</a> that human activities have warmed the planet by 1 C above pre-industrial levels. However, ecological communities do not respond to global averages. Regional changes, which can vary substantially from one place to the next, are far more relevant when trying to understand the ecological response to warming temperatures. </p>
<p>Phenology is the timing of seasonal events in plants and animals, and a powerful lens through which to observe the effects of climate change. </p>
<p>For example, the Japanese have tracked the emergence of blossoms on Kyoto cherry trees for more than 700 years. These records have allowed modern researchers to reconstruct springtime temperatures in Japan <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/joc.1594">since the ninth century</a>, revealing cold periods associated with long‐term solar cycles. </p>
<p>The impact of climate change does not end with plants. Shifts in plant phenology create other indirect responses that can reverberate throughout the food web. Scientists have a term for this: phenological mismatch. These occur when the seasonal timing of one interacting species falls out of sync with that of another’s. For example, advances in the timing of vegetation development in Greenland have hurt populations of caribou, whose annual calving season <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2008.0463">no longer matches</a> the timing of the most nutritious forage. </p>
<p>This is ecologist Eric Post’s “<a href="https://www.jstor.org/stable/j.ctt2jc8jj">thief-in-the-night</a>” analogy: the idea that it is the indirect effects of climate change that pose the greatest threat to ecological communities.</p>
<h2>Climate change and Alberta’s grizzly bears</h2>
<p>Of the IPCC’s four climate projections, our study used the moderate-emissions scenario (called RCP4.5). We found that by 2080, buffaloberry fruit across Alberta’s grizzly bear range will ripen an average of three weeks earlier than present. This advancement increases to 37 days in the higher-altitude subalpine zones. </p>
<figure>
<iframe src="https://player.vimeo.com/video/326550646" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">A side-by-side comparison of seasonal buffaloberry development across Alberta grizzly bear range. The imagery covers the appearance of the first flowers to the dispersal of fruit. The red wave indicates the ripening of berries.</span></figcaption>
</figure>
<p>This shift will have major implications on the province’s dominant omnivore, as well as other local fruit-eaters. Grizzly bears are highly food-focused, and their movements are driven by the availability of seasonal food sources. </p>
<p>During late summer, scientists have documented <a href="http://parkscanadahistory.com/wildlife/report-34.pdf">individual bears in Alberta</a> consuming up to 200,000 berries per day. Changing the timing of this critical food resource means that we can expect to see bears at times and in places where we’re not used to seeing them. </p>
<h2>A threat to reproductive rates</h2>
<p>An abbreviated, mid-summer ripening of buffaloberry will also widen the gap between prime feeding season and hibernation. This could alter the reproductive rates of <a href="https://open.alberta.ca/publications/9780778570677">Alberta’s threatened grizzly bear population</a>. </p>
<p>Bears are one of the few species of mammal with “delayed implantation,” where eggs fertilized in the spring can wait for months before the start of pregnancy. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4079694/">Previous research</a> has shown a strong correlation between the body condition of female bears in the fall and their reproductive success.</p>
<p>Bears in good physical condition give birth earlier, lactate longer and have more cubs. Bears without the necessary fat stores may not give birth at all. </p>
<p>These emerging phenological mismatches may also circle back to the buffaloberries themselves. The timing of spring flowering of buffaloberry will also shift earlier, perhaps putting it out of sync with the life cycles of the small-fly pollinators the plant <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4137663/">depends on</a>. </p>
<p>We don’t necessarily expect insect pollinators to advance their emergence at the same pace as buffaloberry flowers, since insects may also respond to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2486.2002.00451.x">other seasonal signals</a> such as hours of daylight.</p>
<p>This is especially problematic for buffaloberry, since it is among the first shrub species to bloom in the spring, when pollinator populations are just beginning to emerge. At that time, there are few other options for pollination. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263262/original/file-20190311-86710-1e27l7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Our research reveals how warming temperatures affect the diet of Alberta’s grizzly bears.</span>
<span class="attribution"><span class="source">Graphic by Fuse Consulting Ltd.</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>If there’s good news in any this, it’s that our growing understanding of the ecological effects of climate change can help policy-makers and engaged citizens make informed decisions. Carbon taxes, targets for greenhouse gas emissions and renewable energy strategies are among the key issues that require our attention.</p><img src="https://counter.theconversation.com/content/113001/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Greg McDermid receives funding from the Natural Sciences and Engineering Research Council (NSERC). </span></em></p><p class="fine-print"><em><span>David Laskin receives funding from the Natural Sciences and Engineering Research Council (NSERC) and Alberta Innovates.</span></em></p><p class="fine-print"><em><span>Scott Nielsen receives funding from Natural Sciences and Engineering Research Council (NSERC).</span></em></p>As warming temperatures shift the availability of key food sources, Alberta’s grizzly bears will be forced to adjust.Greg McDermid, Professor, University of CalgaryDavid Laskin, PhD Graduate, University of CalgaryScott Nielsen, Professor, University of AlbertaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1125392019-02-27T13:24:38Z2019-02-27T13:24:38ZHere’s how Britain’s changing weather is affecting wildlife<figure><img src="https://images.theconversation.com/files/261268/original/file-20190227-150712-1l8espq.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C5168%2C3453&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bloomin' early.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/jessikawoo/13979856128/">J.A.Woodhouse/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The Beast from the East, a polar vortex which brought freezing conditions to the UK, arrived on February 26 2018. Two days later there was a minimum temperature of -11.7°C (10.9˚F) at South Farnborough in Hampshire, and a maximum of only -4.8°C (23.4˚F) at Spadeadam in Cumbria.</p>
<p>In sharp contrast, on February 26 2019, temperatures reached 21.2˚C (70.2˚F) at Kew Gardens in south-west London – <a href="https://www.bbc.co.uk/news/uk-47374936">the warmest winter day</a> since records began. In February 2019, bumblebee queens were out looking for nest sites, adult butterflies were emerging from their winter hibernation and blossom appeared on some trees and shrubs. But what will be the long-term effects of 2019’s early spring?</p>
<p>The relatively new <a href="https://naturescalendar.woodlandtrust.org.uk/what-we-record-and-why/why-we-record/what-is-phenology/">science of phenology</a> examines the timing of the seasons by plotting the calendar records of first plant bud, first flower, first nesting behaviour and first migrant arrivals. Over the past three decades, these records have confirmed that <a href="https://www.thoughtco.com/spring-phenology-and-global-climate-change-1203890">spring temperatures are generally arriving earlier</a> in the year.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1100432569617797122"}"></div></p>
<p>As the days get longer and warmer in the northern hemisphere, bird species such as the barn swallow follow these natural cues to depart for British habitats, where they nest and rear their young. These insectivorous migratory birds time their breeding season to coincide with insects being present in sufficient numbers to feed their young. </p>
<p>While the main trigger for birds to migrate from their overwintering grounds to Britain is the length of daylight, temperature will also fine-tune the arrival date. An early spring means that insects could emerge and breed before migratory birds arrive.</p>
<p>Once in the UK, the birds may find there are fewer insects to eat and this results in fewer chicks fledging, which leaves their predators, including the sparrowhawk and the stoat, with less to eat. The disconnect between the arrival of insectivorous birds and the abundance of insects ripples through the ecosystem, affecting other animals and plants that at first sight may not seem linked to this seemingly benign change.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=513&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=513&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=513&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=644&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=644&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261214/original/file-20190227-150712-32wgdn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=644&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A juvenile barn swallow (<em>Hirundo rustica</em>) in West Sussex, UK. Without insects to eat, young birds could starve.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Barn_swallow#/media/File:Hirundo_rustica_-West_Sussex,_England_-chick-8.jpg">Jim Mead/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Of course, much depends on how long the warm weather lasts and what follows. The mild conditions in 2019 have prompted buds to burst on some plants – this makes the flowers and leaves vulnerable if the weather reverts to colder conditions. If the temperature drops to low single figures in degrees Celsius but remains above freezing, growth rate will slow and the plant’s growth will be stunted. A hard frost, on the other hand, would damage or even kill any of the flowers and leaves that have emerged during the warm spell.</p>
<p>At the end of twigs is the apical meristem – the site where rapid cell division generates new plant material which results in the twigs growing longer each year. No longer protected from frosts within a bud, apical meristems are vulnerable to damage by frost. The result is that twigs will stop growing. Rather, a new apical growth point will establish itself from a bud nearer to the main trunk of a tree or the main stem of a bush. The long-term effect is that a twig develops in a different direction, and the plant carries this signature of frost damage for the rest of its life.</p>
<p>An early spring might also accelerate climate change. Scientists at the Vienna University of Technology and the University of Leeds studied satellite data for the northern hemisphere – from southern Europe and Japan up to and including the Arctic tundra – and demonstrated that in many regions of the Earth, an early spring leads, counter-intuitively, to <a href="https://www.nature.com/articles/s41586-018-0555-7">less plant growth</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261215/original/file-20190227-150718-1sn7gkf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Early budding can mean limited growth for the entire year or even no growth on certain twigs if the weather changes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/spring-branch-lime-tree-isolated-75267259?src=cLcDy5CADC9Y8w7-olvcjA-1-28">Haraldmuc/Shutterstock</a></span>
</figcaption>
</figure>
<p>This may be because certain plants have a predetermined growth period. Growth in early spring means an early cessation of growth later in summer or early autumn. Greater plant growth in the spring could also result in increased transpiration – the process by which moisture is drawn through plants from roots to small pores on the underside of leaves, where it becomes vapour which is released to the atmosphere. This causes a higher demand for water during the growing season which cannot be met if the summer and autumn are also dry. The result of this early growth is limited plant growth overall through the entire year.</p>
<p>Plants that do not grow as big as they might <a href="https://www.nature.com/articles/s41586-018-0555-7">absorb less carbon</a>, so reduced plant growth means less carbon stored in vegetation, and that in turn means more carbon dioxide in the atmosphere, more warming and even earlier springs – a positive feedback loop.</p>
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<strong>
Read more:
<a href="https://theconversation.com/the-arctic-is-turning-brown-because-of-weird-weather-and-it-could-accelerate-climate-change-107590">The Arctic is turning brown because of weird weather – and it could accelerate climate change</a>
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<p>Many people have <a href="https://www.theguardian.com/environment/2019/feb/26/i-cant-help-but-be-concerned-readers-spot-early-signs-of-spring">worried</a> about the unseasonable warmth and spring-like conditions of February 2019. As unseasonably mild weather brings about changes in plant growth that could accelerate climate change and widen the disconnect between elements of ecosystems, this unusual week may leave an even more worrying legacy.</p>
<p>However, even in the midst of a winter warm spell, the Met Office forecast predicts less mild and more changeable conditions to come – showery rain in some parts and stormy conditions elsewhere, with overnight frosts still possible. There is even a mention of snow on high ground. Such are the vagaries of the British weather.</p><img src="https://counter.theconversation.com/content/112539/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Philip James does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Record heat in February 2019 caused shock and delight in equal measure. Behind the balmy weather lie challenges for British wildlife.Philip James, Professor of Ecology, University of SalfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/981612018-07-05T20:03:41Z2018-07-05T20:03:41ZFriday essay: frogwatching – charting climate change’s impact in the here and now<figure><img src="https://images.theconversation.com/files/225237/original/file-20180627-112641-1566r56.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Whistling tree frogs, Litoria verreauxii, are one of the species monitored around Canberra for their response to climate change. </span> <span class="attribution"><span class="source">Catching the eye/flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>We’ve arranged to meet in a gravel car park at the foot of Mt Majura, a darkening wedge above us in the dusk. My daughter and I wait in the car. It’s winter. A woman passes along the nearby pavement, guiding her way by torchlight. Canberra’s streets are kept dim, I learned recently, for the sake of astronomers at nearby Mt Stromlo observatory. In the decade I’ve lived here, I’ve had an ambivalent relationship with Canberra, but the idea of a city that strikes bargains with stargazing scientists to restrict light pollution leaking skyward is endearing.</p>
<p>There are other endearing things. One of them is the amount of bushland interspersed throughout the urban landscape. You can be in the middle of suburbia one minute and bushwalking on nearby Black Mountain, Mt Majura or Mt Ainslie ten minutes later. This kind of mixed landscape is ideal for the citizen science project we’re about to launch into this evening, as soon as the co-ordinator of the <a href="http://fw.ginninderralandcare.org.au/">ACT and Region Frogwatch Program</a>, Anke Maria Hoefer, arrives for our first training session.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=548&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=548&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=548&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=689&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=689&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225837/original/file-20180703-116143-1wc6kot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=689&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The eastern common froglet, Crinia signifera.</span>
<span class="attribution"><span class="source">eyeweed/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The program runs a community-based annual Frog Census framed against a rapid global decline in frog numbers over the past four decades and the extinction of many frog species. The census began in 2002, and the resulting long-term dataset on the abundance and distribution of local frogs has enabled additional research activities including a climate change project. We’ll take part in the latter, which monitors behavioural shifts in frogs through recording their calls at particular sites each week from June until October. </p>
<p>We’re here for a few reasons. One is to get a lived sense of climate change in our immediate urban surroundings. Plus, I want to make a contribution, however small, to the huge dilemma of climate change and its impacts; give my 13-year-old daughter a taste of scientific fieldwork in case it appeals to her; get to know our local surroundings better; and, as a writer, to think about practices that don’t simply observe or contemplate place but also participate in constructive activities at those same locales.</p>
<p>Numerous commentators have observed that the vast and intangible scale of climate change may be an impediment to more people <a href="http://www.futureearth.org/blog/2017-jun-7/increase-ocean-literacy-narratives-hold-promise">taking action over our warming atmosphere</a>. We know through the science that climate is shaped by the working of the entire planetary system – the earth’s interactive ocean, atmosphere, land and ice systems all linked to human activity. Depending on where you live, (but not in the Pacific Islands, the deltas of Bangladesh, Arctic Canada, or <a href="https://theconversation.com/hope-and-mourning-in-the-anthropocene-understanding-ecological-grief-88630">drought-stricken rural Australia</a>), its impacts can seem far-removed from our own lives and the places we know best and care most about. With care, often, comes action. What can seem an amorphous, far-fetched threat is brought closer to home through studies such as Frogwatch.</p>
<p>The project studies the impact of <a href="https://theconversation.com/early-birds-how-climate-change-is-shifting-time-for-animals-and-plants-34766">climate change on phenology</a>, or seasonal behaviour. Most frogs only call during the mating season, which is triggered by temperature and rainfall. Different species mate at different times and volunteers record the onset of mating calls from winter breeders (whistling tree frog and common eastern froglet), early and mid-spring breeders (spotted grass frog, plains froglet, striped marsh frog and smooth toadlet), and late spring to summer breeders (eastern banjo frog and Peron’s tree frog).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/early-birds-how-climate-change-is-shifting-time-for-animals-and-plants-34766">Early birds: how climate change is shifting time for animals and plants</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225264/original/file-20180628-112598-45q9zp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An eastern banjo frog, Limnodynastes dumerili.</span>
<span class="attribution"><span class="source">David Cook/flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Frogs are known as an “indicator species” for water quality and local ecosystem health. With their permeable, membranous skin, through which respiratory gases and water can pass, and their shell-less eggs laid in water, they are sensitive to even low concentrations of pollutants in water and soils. In this study, frogs give a different kind of warning – as they begin calling earlier in the season, they reveal and give voice to the warming climate we now all inhabit.</p>
<p>The project is fortunate enough to be able to build upon weekly counts of calling frogs by ecologist Will Osborne during the 1980s and 1990s in the Canberra region. Effects of climate change can be incremental. They can also be non-linear, as scientist <a href="https://theconversation.com/profiles/pep-canadell-16541">Pep Canadell</a> explained to me in a recent interview. “Climate change expresses itself through extremes. It’s not a linear relationship of impacts,” he said. </p>
<p>This mixture of incremental change and unpredictable “expressions” can be difficult to record in the short term. With this in mind, the Frogwatch project builds on Osborne’s historical data along with the Frog Census data to chart changing trends. A preliminary comparison reveals that the breeding season of some local frog species might be commencing up to six weeks earlier than 40 years ago.</p>
<h2>A sonic world</h2>
<p>Headlights sweep into the car park and Anke Maria arrives with a visiting German student who is also researching frogs. Anke Maria is a whirlwind of talk and activity, honing in on my daughter as we zip our down jackets, pull on beanies and gloves, switch on torches and head up a gravel fire trail toward the first dam, known as FMC200. Only metres later we stop at the base of a narrow drainage gully. It’s been a dry winter, but with a patch of recent rainfall a miniature sump-like drainage area at the base of the gully is alive with frog calls. </p>
<p>“That’s <em>Crinia signifera</em>,” Anke Maria explains, making what seems a perfect imitation of its repetitive call. “How would you describe it?” she asks. My daughter turns to me. The call is repetitive, creaking. We struggle to think of descriptions. It’s like trying to put a flavour into words. </p>
<p>“Who do you think is calling? The male or female?” Anke Maria asks. My daughter pauses, pondering. “The female,” she hazards a guess. “Good try,” says Anke Maria, “but only the male frog calls. Except when the female makes a warning call.” She imitates this staccato warning sound. “And why do you think the males are calling?” Again my daughter pauses to consider.</p>
<p>We continue walking up the gravel slope amid shadowy shapes of eucalypt trees, a tangle of gorse and acacia undergrowth, a row of looming metal electricity pylons strung along the lower contour lines of Mt Majura. </p>
<p>“They could be hungry or they found food,” my daughter replies.</p>
<p>“Good thinking, but they’re calling to attract a girlfriend. And do you know, scientists think that each frog species can only hear the calls of their own species. It’s like tuning into a radio station. There are many different stations, but we can only tune into one at a time. A female whistling tree frog can only hear a male whistling tree frog, a female corroboree frog can only hear a male corroboree frog.”</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australian-endangered-species-southern-corroboree-frog-16189">Australian endangered species: Southern Corroboree Frog</a>
</strong>
</em>
</p>
<hr>
<p>They recognise the frequency and intensity or pitch of the call, she explains, and also the pattern of the call or its pulse structure. “This helps the female find a mate from their own species and not get confused by other frogs.”</p>
<p>We ponder this sonic world where one species can be deaf to another, turn left down a narrow walking track, torchlight bobbing along with our footsteps, illuminating tussocks of grass, fallen branches, shrubs, stones, until we reach the dam. “This is for you,” Anke Maria passes a thermometer. “You do it,” she tells my daughter. First we record the ambient temperature then my daughter squats at the edge of the water, waving the thermometer gently through the shallows. We note the weather: light cloud cover, low breeze. We estimate the dam’s surface area and depth. Then our small group falls silent as Anke Maria switches on her phone audio-recorder. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225263/original/file-20180628-112628-1ocddbc.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The dam, FMC200 on Mt Majura.</span>
<span class="attribution"><span class="source">Saskia Beudel.</span></span>
</figcaption>
</figure>
<p>For three minutes we hold still and listen. There’s the low hum of the city below, an ambulance siren swells and recedes, distant traffic, the shuffle of our down jackets as we try not to move, someone sniffs in the chill winter air – and the frogs. You can hear them interspersed across space, some close, some farther away, among vegetation rather than water. Because of Anke Maria’s explanation, I understand now these are not call-and-response sounds. They are invitations, serenades, statements of presence, lures. Sometimes the calls come in a cluster, other times at staggered unpredictable intervals. There are at least two species here, I guess. In the distance, a mopoke calls.</p>
<p><audio preload="metadata" controls="controls" data-duration="198" data-image="" data-title="" data-size="998582" data-source="" data-source-url="" data-license="" data-license-url="">
<source src="https://cdn.theconversation.com/audio/1215/fmc200-20-8-17.mp3" type="audio/mpeg">
</audio>
<div class="audio-player-caption">
</div></p>
<p>When Anke Maria switches off her phone, we relax into movement again. As we walk towards FMC210, our second dam, she tells us we’ve just heard a whistling tree frog (<em>Litoria verreauxii</em>). “How would you describe his call?” Anke Maria asks.</p>
<p>My daughter decides on a stick dragged across a rough, hollow surface. Anke Maria makes the call. Her imitations are pitch perfect, an art form. She will be the one who checks the recordings that non-specialist volunteers send in weekly, uploaded to the Frogwatch website. We will make our guesses at species we’ve heard, but she will verify with her trained ear, a labour-intensive task. </p>
<p>In our information pack is a CD of local frog species. When we get home we lie on the carpet and listen, the house filled with frog noise.</p>
<h2>A new frog</h2>
<p>A week later, on our first trip into the dark alone, the evening is silvered and rigid with frost, as if everything is held together in some different, more metallic way. It’s three below zero and falling. Our breath steams, our boots crunch, the bush is still. I sense something in a dead tree ahead before I see it, a tawny frogmouth, grey, motionless, an outcropping like a broken limb. We pause several steps away and it regards us, head half swivelled, a little tuft of feathers at the base of its beak.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225240/original/file-20180627-112623-16epsyr.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A tawny frogmouth.</span>
<span class="attribution"><span class="source">Saskia Beudel</span></span>
</figcaption>
</figure>
<p>The following week, on our descent from the dams, once again a frogmouth is in the same tree. A second bird perches a few metres away. They are bound together in some mute, still business. They survey us. We move on with subdued steps. Beyond the birds, the first row of suburban houses begins. We thread our way back to the car with a sense of secrecy and adventure, past back fences, patches of bright window, catching fugitive glimpses of other people’s lives through a half-open door, a crack in a curtain, the blue flicker of TV light.</p>
<p>At the dams we make our recordings. Air temperature, water temperature, ascending over the weeks. On the far side of Mt Majura lies the airport. Often early into a sound recording, a plane takes off, blotting out all other sound. Ecologist Will Osborne tells me he has observed that the aeroplane sound seems to overlap the call parameters (pitch and pulse structure) of the Common Eastern Froglet. Whenever a plane goes over, the froglet stops calling while other species continue – machine and creature competing on the airwaves. </p>
<p>When I upload the recordings, Anke Maria responds and confirms (or not) my guesses at species. You should soon hear <em>Crinia parinsignifera</em> she emails, so keep your ears peeled for a high pitch narky baby cry!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225838/original/file-20180703-116132-1xugpqr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The eastern sign-bearing froglet, Crinia parinsignifica.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/teejaybee/2591702639/in/photolist-6uVCyq-4X29Ug">teejaybee/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Her enthusiasm is infectious, her aural sketches vivid, memorable. When we hear the new frog, I know exactly what it is. Everyone on the team, each with sites to attend scattered across Canberra, has been waiting for this particular call. </p>
<p>It might show that an <a href="http://www.abc.net.au/news/2016-08-26/frogs-calling-earlier-due-to-warming-climate-frogwatch/7787960">early spring breeder is shifting its season into winter</a>. This minor-sounding alteration has a cascade of flow-on effects. Frogs stagger breeding seasons, giving each species its portion of acoustic space to call, breed, then when eggs hatch into tadpoles to feed (a mode of “time sharing” water and its resources). If seasons shift, merge and overlap, competition for resources intensifies, and survival can be jeopardised.</p>
<p>But this year it’s a cold, dry winter. This telling species, <em>Crinia parinsignifera</em>, is calling two weeks later than last year (when it called early). Meanwhile northern Australia is experiencing its <a href="http://www.abc.net.au/news/2017-08-01/australia-records-hottest-july-on-record-bom-says/8762560">warmest July on record</a>. Non-linear. As the monitoring season progresses, dam levels drop. By the end of October, waters have fallen almost silent.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225238/original/file-20180627-112604-1no9dvt.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Measuring the drop in water levels.</span>
<span class="attribution"><span class="source">Saskia Beudel</span></span>
</figcaption>
</figure>
<p>Will Osborne sends an email around, explaining that cold nights and low water levels will make it hard to interpret this season’s counts. “Most species feel insecure about going out onto that exposed mud and trying to find a call site or searching for mates! It will be a big rush when the weather warms and we get good rains – the calling sequence could be condensed this year which will be interesting…”</p>
<h2>Taking action</h2>
<p>Many volunteers join Frogwatch because they want to participate in a hands-on, climate change-related study with real life applications. “They highly value the opportunity to be involved in climate change actions,” Anke Maria says. She captures one of the dilemmas of our times. Many people want to take action but are unsure how. As artist <a href="https://www.ted.com/speakers/natalie_jeremijenko">Natalie Jeremijenko observed</a>): “What the climate crisis has revealed to us is a secondary, more insidious and more pervasive crisis, which is the crisis of agency, which is what to do.” Citizen science gives volunteers an opportunity to do something.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/226074/original/file-20180704-73315-c6tv6f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Filling out field data sheets.</span>
<span class="attribution"><span class="source">Saskia Beudel</span></span>
</figcaption>
</figure>
<p>Studies that chart the impacts of climate change here-and-now disrupt the assumption that effects will occur in a distant future or at some remote geographic location (melting ice caps, apocalyptic cities under 20 metres of water). Instead, they start to build a picture of measurable effects experienced at the current level of 1°C warming above pre-industrial levels – let alone at 2°C or above, which is what we’re committing to <a href="http://www.wri.org/sites/default/files/WRI13-IPCCinfographic-FINAL_web.png">based on current emissions rates</a>. In the Canberra region alone, studies are being conducted into impacts of global warming on urban lizard species (who reside next to the local DFO) and alpine pygmy possums.</p>
<p>At a broader scale, Pep Canadell has observed major ecological transformation in Australia that occurred with a 1.2°C increase during the last El Niño. He calls the El Niños a “window into the future because they bring all this heat and put the world where it may be in 30 or 20 years’ time.” </p>
<p>In the last big El Niño of 2015-16, this “future now” included the well-known <a href="https://theconversation.com/coral-bleaching-comes-to-the-great-barrier-reef-as-record-breaking-global-temperatures-continue-56570">bleaching of the coral reef</a>, and <a href="https://theconversation.com/fires-in-tasmanias-ancient-forests-are-a-warning-for-all-of-us-53806">fires in the moist peats of alpine Tasmania</a>. There are no records for the past 8,000 years that there has ever been a fire in this part of the world. In addition to these well publicised events, around <a href="https://theconversation.com/extreme-weather-likely-behind-worst-recorded-mangrove-dieback-in-northern-australia-71880">700 km of mangroves lining the Gulf of Carpentaria died</a> in a month; and the Murray Darling River had one of its worst algal blooms caused by an algae that belonged not in this region but to hotter places in Queensland.</p>
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Read more:
<a href="https://theconversation.com/coral-bleaching-comes-to-the-great-barrier-reef-as-record-breaking-global-temperatures-continue-56570">Coral bleaching comes to the Great Barrier Reef as record-breaking global temperatures continue</a>
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<p>“These ecological signs are unprecedented, all in this little window of a warmer world that the El Niño brought for us,” said Canadell during our interview. He went on to list even more signs. “For some reason these things don’t go through the media enough because of … whatever,” he added.</p>
<p>The Frogwatch project enables volunteers to dwell in an everyday way with such dispersed ecological signals, which, connected together with other studies, provide a larger picture of both current and future impacts. Volunteers are privileged to make their small citizen science contribution to understanding and recording these signs better.</p>
<p>Unfortunately, just as I completed this article, the Frogwatch Program discovered that its funding from the ACT Government was not renewed in the 2018–19 budget. Without core funding, the organisation and its annual Frog Census will cease. The enthusiasm of volunteers will help to collect another season’s data for the climate change study but it too is under serious threat unless alternative funding can be sourced. </p>
<p>When our monitoring season finished last year, I asked my daughter whether she wanted to do it again. “Yes,” she replied without hesitation. “What did you like most about it?” I asked. “I don’t know,” she said, “it was just fun.” And so, as Canberra’s heavy frosts set in, we have begun again, treading up towards FMC200, waiting for frog calls to begin.</p>
<hr>
<p><em>Saskia Beudel’s full interview with Pep Canadell will be published in December 2018 in the journal <a href="https://www.weber.edu/weberjournal">Weber</a>.</em></p><img src="https://counter.theconversation.com/content/98161/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Saskia Beudel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Climate change can seem far removed from our everyday lives, which is why a citizen science program measuring how frogs are dealing with a warming world is so important.Saskia Beudel, Adjunct Associate Professor, Centre for Creative & Cultural Research, University of CanberraLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/831312017-09-19T02:07:12Z2017-09-19T02:07:12ZAs a warming climate changes Kodiak bears’ diets, impacts could ripple through ecosystems<figure><img src="https://images.theconversation.com/files/184317/original/file-20170901-26064-ngq7af.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A brown bear snags a sockeye salmon in Alaska. In warm years, red elderberries ripen early and Kodiak bears leave streams full of salmon to eat them.</span> <span class="attribution"><span class="source">Jonathan Armstrong</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>After several years of studying brown bear ecology on Alaska’s Kodiak Island, I grew used to walking up streams into scenes of carnage. Where bears had killed and eaten spawning sockeye salmon, streambeds were littered with fish heads, jaws and whole carcasses, and plants on the stream banks were flattened. But at the peak of the stream spawning run in 2014, I was puzzled to find no bears or salmon parts. Salmon were dying naturally after spawning and piling up in streams, intact.</p>
<p>I’ve spent the last three years trying to solve this ecological puzzle. After extensive field and lab work along with researchers from <a href="https://www.fws.gov/refuge/kodiak/">Kodiak National Wildlife Refuge</a>, <a href="https://flbs.umt.edu/">Flathead Lake Biological Station</a> and Oregon State University, we arrived at <a href="http://dx.doi.org/10.1073/pnas.1705248114">a fascinating conclusion</a>. </p>
<p>In warm years, another favorite bear food – red elderberries – ripened early enough to overlap with the salmon season. This forced bears to choose between the foods. Surprisingly, almost all bears opted for berries over salmon. This choice has likely altered food webs, and will become increasingly common with expected climate warming.</p>
<p>Our team was struck by the bears’ seemingly counterintuitive switch. Why would bears stop eating a high-protein food loaded with energy? Quickly, though, we realized that our work was an example of a more global concern: What happens when climate change alters nature’s schedule?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186472/original/file-20170918-15679-kfvv1g.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Female bear eating a salmon, Kodiak, Alaska.</span>
<span class="attribution"><span class="source">Caroline Deacy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Timing is everything</h2>
<p>Among the most apparent consequences of a warming climate are shifts in phenology – the timing of key biological events like hatching, blooming or migration. Researchers have found that <a href="http://dx.doi.org/10.1038/nature18608">timing is changing in all types of organisms</a>, but some species are more sensitive to temperature changes than others. </p>
<p>As a result, nature’s timetable is slowly becoming scrambled. Some species that have evolved together, such as <a href="http://dx.doi.org/10.1098/rspb.1998.0514">songbirds and caterpillars</a>, are drifting apart in time. Others, such as elderberries and salmon, are drifting together. Species which once were temporally separated are now able to interact, with unpredictable results.</p>
<p>In a typical year on Kodiak Island, the bears we study eat spawning salmon in small streams during midsummer, shift to berries in late summer and finally switch back to catching salmon in rivers and lakes in fall. <a href="http://dx.doi.org/10.1890/15-1060.1">This pattern</a> provides bears with a continuous supply of high-quality foods. The bears can be in only one place at a time and can eat only so much each day, so they benefit when their resources are <a href="https://voices.nationalgeographic.org/2016/03/31/surfs-up-for-wildlife/">spread through time</a>. When their key foods overlap in time, they must choose which to eat and which to skip.</p>
<h2>Tracking bear diets</h2>
<p>Each year, a team including myself, Kodiak Refuge biologist Bill Leacock, field technician Caroline Deacy and several volunteer crew members contended with swarming insects, rain and thick brush to collect data on salmon runs, berry crop timing and bear behavior. We worked out of a remote field camp accessible only by float plane, without phone reception or internet access.</p>
<p>We developed multiple data sources on bear feeding habits, each of which filled in part of the ecological puzzle. First we placed 12 time-lapse cameras along streams to see how bears responded to salmon runs before and after berry ripening. Next we used GPS collars to track female bears before, during and after the red elderberry season. </p>
<p>To make sure that we were not just witnessing a local phenomenon, we analyzed data collected during aerial surveys of bears fishing at streams and rivers across southwestern Kodiak Island. Finally, we conducted a scat survey to make sure that bears were eating elderberries instead of some mystery food. Together, our data showed that bears switched to eating red elderberries even when streams were packed with spawning salmon!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186474/original/file-20170918-420-1l7gl8w.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Red elderberries in Kodiak, Alaska.</span>
<span class="attribution"><span class="source">Caroline Deacy</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why swap fish for fruit?</h2>
<p>Why this happened is still an open question, but evidence suggests the bears were responding to protein content in their food choices. In captivity, <a href="https://doi.org/10.1644/13-MAMM-A-161">bears offered a buffet of foods</a> will not simply choose the most energy-rich option – that is, food that is 100 percent fat. Instead, they select a balanced diet that includes a moderate amount of protein, or around 17 percent of their total caloric intake. We don’t know exactly why 17 percent is a magic number, but it maximizes the rate at which bears gain weight. </p>
<p>Spawning salmon have burned through their fat stores, and their bodies are about 80 percent protein. Most common berries, such as blueberries, contain very little protein, but red elderberries are about 13 percent protein, so they help bears fatten quickly.</p>
<p>The main worry with respect to bears’ health is that increasing overlap between foods will force bears to choose between them. This would be like having to choose between eating breakfast and lunch, both served at 8:00 a.m., and then going hungry until dinner. Luckily Kodiak is a bear paradise with many suitable foods, including genetically diverse salmon populations that spawn at different times in different habitats. Bears that skip early runs of stream-spawning salmon can still catch salmon that spawn later on rivers and beaches. Diverse salmon runs ensure that bears will always have something to eat.</p>
<p>However, in the northwest United States, once-robust salmon populations are now dominated by homogeneous hatchery populations. Here, increasing overlap between foods would likely have a larger impact on predators such as bears. The key lesson for conservation is that disruptions caused by climate change will be less harmful to the species we care about if we keep nature <a href="http://dx.doi.org/10.1126/science.1261824">complex and intact</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/g00fAKG31lw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bears and other animals carry salmon into forests, distributing nutrients back into the ecosystem.</span></figcaption>
</figure>
<h2>Impacts beyond streams</h2>
<p>What about the rest of Kodiak’s ecosystem? Salmon accumulate nutrients in their bodies as they grow in the ocean and then <a href="https://doi.org/10.1046/j.1523-1739.1995.09030489.x">deliver these nutrients into fresh water</a> when they head upstream to spawn. When they die after spawning, their bodies provide fertilizer for plants and tasty snacks for scavengers. </p>
<p>Bears <a href="https://doi.org/10.1007/s10021-004-0063-5">spread the bounty</a> onto land by carrying fish from streams and leaving partially consumed carcasses far from water. This makes salmon available to smaller animals that cannot capture fish themselves, and fertilizes plants far from spawning streams. When bears ditch salmon, this carcass distribution stops, potentially harming species that depend on bear-caught salmon.</p>
<h2>Rescheduling nature</h2>
<p>When people think about how wildlife is impacted by a warmer world, they often think of overheating animals or polar bears standing on melting icebergs. We discovered a more subtle effect of warmer temperatures: By rescheduling bears’ feeding options, climate change dramatically altered bear behavior, halting an iconic predator-prey interaction. Scientists, naturalists and even gardeners are seeing changes in biological timing throughout nature, so we should expect to witness more surprising species interactions in the future.</p><img src="https://counter.theconversation.com/content/83131/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Deacy receives funding from the Kodiak National Wildlife Refuge, US Fish and Wildlife Service. </span></em></p>Climate change is making berries ripen early in Kodiak, Alaska, luring bears away from eating salmon. This shift may not hurt the bears, but could have far-reaching impacts on surrounding forests.William Deacy, Postdoctoral Research Fellow, Oregon State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/822332017-08-24T00:32:53Z2017-08-24T00:32:53ZAs climate change warms the Northeast, some snowshoe hares stay brown all year<figure><img src="https://images.theconversation.com/files/183023/original/file-20170822-30547-v3wz8m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Denali National Park, Alaska.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/bDLgMf">Tim Rains/NPS</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The quintessential image of a snowshoe hare (<em>Lepus americanus</em>) is a pure white bunny – although it is a hare, not a rabbit – nestled in powdery snow, gazing out from under the overhanging branches of a balsam fir. I can almost see my breath and hear sleigh bells just thinking about it. </p>
<p>But in Pennsylvania, powdery snow has a short life expectancy during our winters’ freeze-thaw cycles. In southern Pennsylvania, it’s not unusual for snowstorms to turn completely to rain, and it can happen almost anywhere in the state. As a result, in much of Pennsylvania it’s rare to sustain complete snow cover throughout winter, and will become rarer as climate change results in warmer temperatures across the state.</p>
<p>And balsam firs occur only in tiny, relict patches scattered across northern Pennsylvania, left over from retreating glaciers. Our forests are dominated by trees that shed their greenery every winter, such as <a href="http://envirothonpa.org/documents/2-1_ForestTypesPA_001.pdf">oak and hickory</a>. Conifers are more common to our north in New York state, New England and Canada.</p>
<p>For millennia snowshoe hares’ pure white coats have kept them warm and protected them from predators. But if snowshoe hares are going to make it in Pennsylvania, they will have to have to leave that balsam hiding spot and rethink their thick white winter coats. That appears to be what they are doing. In a recently published <a href="https://doi.org/10.1139/cjz-2016-0165">study</a>, my colleagues and I found that snowshoe hares have adapted to the warmer winters of Pennsylvania – but it’s unclear whether they can continue to change as quickly as the climate.</p>
<h2>Adapting to warmer winters</h2>
<p><a href="http://davidjachowski.weebly.com/people.html">Laura Gigliotti</a>, <a href="http://ecosystems.psu.edu/directory/mjs72">Michael Sheriff</a> and I recently published a <a href="https://doi.org/10.1139/cjz-2016-0165">study</a> comparing physiological characteristics of snowshoe hares from Canada’s Yukon with those in Pennsylvania. We documented several interesting differences between the two groups by tracking movements of 70 Pennsylvania hares with radio collars, fitting some of them with temperature sensors and measuring characteristics of their winter coat.</p>
<p>As in all other studies of snowshoe hares, the ones we tracked sought out habitats with dense vegetative growth. Hares in Pennsylvania were most likely to rest in locations thick with shrubs and small trees beneath the forest canopy, where you could see little beyond 30 feet (10 meters). Our measurements indicated that these areas had at least 80 percent visual cover. We never found hares resting in areas with less than 20 percent visual cover. Even though Pennsylvania hares rarely have access to the same kind of ground-hugging cover that conifers provide their northern cousins, they appear to use native vegetation to hide effectively from predators.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1023&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1023&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1023&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1286&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1286&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183027/original/file-20170822-30529-1kac128.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1286&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Snowshoe hares that turn white during Pennsylvania winters with scant snow are easy targets for predators.</span>
<span class="attribution"><span class="source">Diefenbach Lab/PSU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In northern climates, hares select habitats that provide both hiding cover from predators and protection from cold temperatures. However, in Pennsylvania we found that snowshoe hares’ resting spots were not any warmer than locations we chose at random. It appears that for our hares, winter temperatures aren’t much of a concern. </p>
<p>Reinforcing that fact, we also found that Pennsylvania snowshoe hares produce relatively light-duty fur coats. The downy hairs of their underfur were 58 percent less dense than those of their northern counterparts, while their guard hairs (long hairs that protect the insulating underfur) were 32 percent less dense and 20 percent shorter. Our temperature sensors indicated that Pennsylvania hares produced less body heat than hares from the Yukon, which suggests that they have slower metabolisms.</p>
<h2>Hares of a different color</h2>
<p>Our most fascinating discovery was that some snowshoe hares in Pennsylvania do not change color from brown to white in winter. We captured three individual hares in January that had brown coats except for some white coloration around the nose, feet and ears. Although this phenomenon <a href="https://www.sciencedaily.com/releases/2009/02/090224220347.htm">has been documented in the Cascade mountain range</a> in the Pacific Northwest, it had never been documented in eastern North America until now. </p>
<p>We were not able to test the hair density of individuals that retained a brown coat in winter, so we can only speculate about why they had this unusual adaptation. We have two hypotheses: first, that the hares may have kept their summer coat because they did not need the insulation; second, that there may be some reduced predation risk for hares that retain a brown coat in an environment where persistent snow cover is unpredictable.</p>
<p>All of these physical and physiological differences help snowshoe hares survive in the warmer climate of Pennsylvania. Our findings are intriguing, although more range-wide studies of snowshoe hare could help us better understand how snowshoe hares contend with warmer winter conditions.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183025/original/file-20170822-30093-4kk072.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Pennsylvania snowshoe hare that has retained its brown coat in winter.</span>
<span class="attribution"><span class="source">Diefenbach Lab, PSU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Changing too slowly</h2>
<p>Will these physiological adaptations be enough to sustain snowshoe hare populations in the face of climate change? In 2004 I studied the <a href="https://www.eaglehill.us/NENAonline/articles/NENA-23-2/14-Diefenbach.shtml">distribution of snowshoe hares across northern Pennsylvania</a>. By modeling the characteristics of where we found hares present compared to where they were absent, we showed that they were most common in the coldest, snowiest parts of Pennsylvania. One area is in a part of northwestern Pennsylvania that receives a lot of lake-effect snowfall from the Great Lakes, and the other is in the higher plateau region of northeastern Pennsylvania. Hunter harvests of snowshoe hares from 1983 through 2011 indicate that harvests now occur mostly in those same regions of Pennsylvania.</p>
<p>Snowshoe hare populations reach their highest densities in early successional habitat, which has dense vegetation that provides both food and cover to hide from predators. Creating suitable habitat by applying best management practices to timber harvests or controlled burns, in the right amounts and locations, could help snowshoe hare populations persist despite climate change. </p>
<p>Unfortunately, <a href="http://dx.doi.org/10.1098/rspb.2015.3104">research in Wisconsin</a> has concluded that the duration of snow cover is a bigger problem for snowshoe hares than the availability of forest cover. If this is true, based on projected climate change in Pennsylvania, we predict snowshoe hares’ range will continue to contract northward. We don’t have enough information to say whether snowshoe hares, even those of a different color, are adapting fast enough to persist in Pennsylvania. </p>
<p>Like many other species, snowshoe hares are found across a range of climatic conditions. Understanding how a species copes in different environments can help us understand where it will continue to thrive in our changing world.</p><img src="https://counter.theconversation.com/content/82233/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Duane Diefenbach is an employee of the U.S. Geological Survey and receives funding from the Pennsylvania Game Commission.</span></em></p>Snowshoe hares in warmer zones have thinner fur, and some are not turning white in winter. As climate change warms the Northeast, will this species adapt?Duane Diefenbach, Adjunct Professor of Wildlife Ecology and Leader, Pennsylvania Cooperative Fish & Wildlife Research Unit, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/347662015-01-06T19:23:11Z2015-01-06T19:23:11ZEarly birds: how climate change is shifting time for animals and plants<p>Every Spring, the blanket of Australian alpine snow starts to melt, and the Mountain Pygmy Possum wakes up from its seven-month-long hibernation. </p>
<p>Naturally after so long under the snow, its first thought is to find food. But over the last few years, the <a href="http://aaarjournal.org/doi/abs/10.1657/1938-4246-41.2.212">snow’s been melting earlier</a>, and an important food source – the Bogong moth – is <a href="http://link.springer.com/article/10.1007/s11629-010-1115-2">arriving later</a> on its yearly migration, <a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=267#threats">leaving these endangered possums to go hungry</a>. </p>
<p>In Australia, spring-time events on the land, as well as in freshwater and marine systems are now <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0075514">generally occurring earlier</a> than they used to.</p>
<p>The time at which certain events happen in the lives of animals or plants – such as when moths or birds start their annual migration, or when plants flower – is mostly influenced by temperature, although day length and rainfall can also play a part. </p>
<p>The timing of these life cycle events and their interaction with the seasonal climate is called phenology.</p>
<p>Since phenology is sensitive to small changes in the environment, any changes in timing can help highlight the impact of climate change on natural and managed systems. You can help record these changes through the ClimateWatch app developed by the Bureau of Meteorology, Earth Watch Institute and the University of Melbourne.</p>
<h2>Starting early</h2>
<p>The life cycles of many plants and animals affect our day-to-day lives, and understanding these cycles is important for our survival. To successfully produce food or hunt, we need to understand animal behaviour and plant growth – and how these are linked to the environment.</p>
<p>In Australia, the breeding season and migration of many birds is beginning earlier by an average of <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0075514">2.6 days per decade</a>.</p>
<p>For many Australian plants, flowering, fruiting and harvesting is starting earlier by an <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0075514">average of 9.7 days per decade</a>.</p>
<p>Flowering also means the presence of pollen in the air. What was once thought of as the “pollen season” is also changing as the climate changes.</p>
<p>For many people, airborne pollen is a source of suffering – for asthma sufferers who are allergic to pollen, and for those with hay fever, pollen can mean sneezing and wheezing. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66929/original/image-20141211-6027-jl584s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some people will be less enthused about a longer pollen season.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/brookenovak/437103661">Brooke Novak</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In <a href="http://www.pnas.org/content/108/10/4248.abstract">North America</a> the length of the ragweed pollen season, one of the biggest causes of hay fever, is now 13-27 days longer than in 1995 (depending on location). The longer pollen season is linked to recent warming, delays in the first frost of Autumn, as well as the number of frost-free Autumn days. </p>
<p>Similar changes have also been found in Europe. Researchers in <a href="http://www.annallergy.org/article/S1081-1206%2809%2900119-7/abstract">Italy</a> found that the pollen season for several allergenic plants was up to 85 days longer in recent decades, with the pollen season starting earlier now than in the 1980s.</p>
<p><a href="http://www.nature.com/nclimate/journal/v2/n4/full/nclimate1417.html">Wine grapes</a> in southern Australia are also maturing earlier – on average eight days earlier per decade than they were in 1985. These changes are related to increasing air temperatures and decreasing moisture in the soil. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66927/original/image-20141211-6030-17vzwjw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wine grapes are now maturing earlier than they used to, thanks to climate change.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/werkman/7376268882">Peter Werkman – www.peterwerkman.nl</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<p>The grape growing season is likely to shorten which will mean changes to the areas suitable for particular varieties. At least <a href="http://www.theage.com.au/business/climate-drives-big-wine-deal-20100816-1272s.htm">one winery</a> has already bought vineyards in Tasmania as a way of dealing with a warming climate.</p>
<h2>A Northern Hemisphere bias</h2>
<p>Most of the reports of changes in species phenology have come from the Northern Hemisphere. This may be partly due to the dramatically visible seasonal changes over this region (first snow for example). </p>
<p>“Firsts” in these regions, such as the arrival of migratory birds or flowering, are very obvious and easy to record. </p>
<p>Some phenological events are also documented because of cultural significance. In Japan, the date of the first bloom of <a href="http://link.springer.com/article/10.1007/s00484-009-0272-x#">cherry blossoms</a> is known from as far back as the ninth century. </p>
<h2>Changing species relationships</h2>
<p>Box-ironbark forests are unusual in that they have trees which flower during winter. These flowers are a vital food source for nectar-dependent woodland birds. </p>
<p>Occasionally, these ironbarks fail to flower, leaving dependent woodland birds short of a vital food supply. </p>
<p><a href="http://link.springer.com/article/10.1007/s10666-006-9063-5">Historical records</a> from 1945 to 1970 of red ironbark flowering in the Rushworth Forest in Victoria, indicate that no flowering occurred in only four of the 26 years. </p>
<p>However, a more <a href="http://onlinelibrary.wiley.com/doi/10.1111/ddi.12230/abstract">recent study</a> from 1997 to 2007 of red ironbark flowering found that the number of years with no flowering had increased. Over the 11-year study, there were four years with no flowering, with three of the failures occurring in the final six years. These flowering failures may have contributed to recent declines in the number of woodland birds in that forest.</p>
<p>Despite these snapshots, an Australia-wide understanding of the impacts of climate change is needed, including records of phenology from many more regions. </p>
<p>A new app means you can now contribute to recording species phenology in Australia. The Bureau of Meteorology, Earth Watch Institute and the University of Melbourne have developed <a href="http://www.climatewatch.org.au/">ClimateWatch</a>, where you can record the life cycle events of plants and birds, spiders and whales and more.</p><img src="https://counter.theconversation.com/content/34766/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marie Keatley has received funding from ARCNESS, Australian Government and the Dahl Trust. She is a founding partner of ClimateWatch and a member of its Steering Committee.</span></em></p><p class="fine-print"><em><span>Lynda Chambers is a founding partner of ClimateWatch and a member of its Steering Committee.</span></em></p><p class="fine-print"><em><span>Paul Beggs receives funding from New South Wales (NSW) Environmental Trust (NSW Government), and is a member of the Australian Aerobiology Working Group which was supported by the Australian Centre for Ecological Analysis and Synthesis and co-sponsored by untied funds from Merck Sharp and Dohme.</span></em></p>Every Spring, the blanket of Australian alpine snow starts to melt, and the Mountain Pygmy Possum wakes up from its seven-month-long hibernation. Naturally after so long under the snow, its first thought…Marie Keatley, Adjunct Associate, Department of Forest and Ecosystem Science, The University of MelbourneLynda Chambers, Principal Research Scientist at the Centre for Australian Weather and Climate Research, Australian Bureau of MeteorologyPaul Beggs, Environmental Health Scientist, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.