tag:theconversation.com,2011:/us/topics/acoustic-monitoring-36160/articlesAcoustic monitoring – The Conversation2023-05-23T00:15:39Ztag:theconversation.com,2011:article/2052232023-05-23T00:15:39Z2023-05-23T00:15:39ZGood vibrations: how listening to the sounds of soil helps us monitor and restore forest health<figure><img src="https://images.theconversation.com/files/526930/original/file-20230518-12204-6wif25.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4307%2C2851&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.pxfuel.com/en/free-photo-xnwfk">pxfuel</a></span></figcaption></figure><p>Nurturing a forest ecosystem back to life after it’s been logged is not always easy. </p>
<p>It can take a lot of hard work and careful monitoring to ensure biodiversity thrives again. But monitoring biodiversity can be costly, intrusive and resource-intensive. That’s where ecological acoustic survey methods, or “ecoacoustics”, come into play. </p>
<p>Indeed, the planet sings. Think of birds calling, <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169534706000218?casa_token=o5SOujsJEcMAAAAA:DGMMfg-Le6QaVPY756llqYodbVZi5hlji-MQ8wNdOFn7dMBOOeT9emo8flURI6x3c7GMLKtx3A">bats echolocating</a>, tree leaves fluttering in the breeze, frogs croaking and bush crickets <a href="https://link.springer.com/article/10.1007/s00114-021-01749-7">stridulating</a>. We live in a euphonious theatre of life. </p>
<p>Even the creatures in the soil beneath our feet emit unique vibrations as they navigate through the earth to commute, hunt, feed and mate.</p>
<p>Eavesdropping on this subterranean cacophony using special microphones can provide researchers with important insights into ecosystem health. Our <a href="https://onlinelibrary.wiley.com/doi/10.1111/rec.13934">new study</a> published in Restoration Ecology shows ecoacoustics can provide an effective way of monitoring biodiversity in soil and in the forest it supports. </p>
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Read more:
<a href="https://theconversation.com/restoring-forests-often-falls-to-landholders-heres-how-to-do-it-cheaply-and-well-204123">Restoring forests often falls to landholders. Here's how to do it cheaply and well</a>
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<img alt="" src="https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525045/original/file-20230509-15-uslr52.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">
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<span class="caption">Setting up the ecoacoustics field trial.</span>
<span class="attribution"><span class="source">Jake M. Robinson</span>, <span class="license">Author provided</span></span>
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<h2>What did the study do?</h2>
<p>Acoustic technology is widely used to survey bats, birds and other creatures. However, scientists who restore degraded ecosystems have yet to make full use of soil ecoacoustics. This is despite its demonstrable effectiveness at detecting small animal vibrations.</p>
<p>Our study applied ecoacoustic tools to measure biodiversity above and below ground in a UK forest. We hypothesised that the soils of forests restored to a healthier state would have a higher diversity of sounds than the soils of recently deforested plots. This is because we assumed more creatures would live in the restored and “healthier” soils, producing a greater variety of sounds that we would detect. </p>
<p>Think of two symphony orchestras. Half of one orchestra’s musicians have fallen ill and can’t play at the concert. This is analogous to a degraded ecosystem. In contrast, the other orchestra has all its members and will therefore be louder, with more complex and diverse sounds.</p>
<p>During the spring and summer of 2022, we collected 378 samples from three recently deforested and three restored forest plots. We created a recording system with special “contact” microphones that we inserted into the ground. </p>
<p>We used a chamber with sound-dampening foam inside to record soil creatures such as earthworms and beetles. This chamber allowed us to block out unwanted signals such as mechanical noise, wind and human activity. The chamber housed the microphone and a 5 litre sample of the soil at each plot.</p>
<p>Our results were exciting. The diversity of sounds was much higher in the soil from the restored plots. This finding confirmed our suspicions that healthier soil would be more tuneful. </p>
<figure class="align-center ">
<img alt="Earthworms making tunnels through soil" src="https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526433/original/file-20230516-23-ofar3e.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">
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<span class="caption">Earthworms make sounds as they digest organic matter and tunnel through the soil.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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Read more:
<a href="https://theconversation.com/how-technology-allows-us-to-reveal-secrets-of-amazonian-biodiversity-182077">How technology allows us to reveal secrets of Amazonian biodiversity</a>
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<h2>Why is monitoring soil health important?</h2>
<p>Our preliminary findings suggest ecoacoustics can monitor life underground. But why is monitoring soil biodiversity so important? Soil health is the foundation of our food systems and supports all other <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/rec.13453?casa_token=7c9REV8s7m0AAAAA%3A8hfzqCbk1BIhUrRZSuqjsj442JnhcIPBGkNT3XmMZRbfi43XbIhLkfFmx47HEaDBTeEsS7finQnOEII">life on land</a>. It should be a global priority.</p>
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<a href="https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Australian magpie cocking its head to one side as it listens for worms in the soil" src="https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1133&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1133&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526439/original/file-20230516-15-mt7dsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1133&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">Birds, including Australian magpies, are known to listen for worms. Scientists can also use the sounds of the soil to assess its health.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>The “unseen” and “unheard” organisms living in the soil maintain its health. Below-ground organisms, such as earthworms and beetles, play a crucial role in <a href="https://link.springer.com/chapter/10.1007/978-0-387-74943-3_8">nutrient cycling</a> and soil health. Without them, forests can’t thrive. </p>
<p>By using ecoacoustics to monitor below-ground biodiversity, ecologists can better assess the effectiveness of restoration efforts. This will allow them to make more informed decisions about the best ways to protect nature.</p>
<p>Using ecoacoustics in restoration efforts could also have important implications for climate change mitigation. Forests are crucial <a href="https://www.nature.com/articles/s41467-021-22459-8">carbon sinks</a>. They absorb CO₂ from the atmosphere and store it in their woody biomass and soils. </p>
<p>In contrast, degraded or deforested areas are significant sources of <a href="https://www.lse.ac.uk/granthaminstitute/explainers/whats-redd-and-will-it-help-tackle-climate-change/#:%7E:text=When%20deforestation%20occurs%2C%20much%20of,Africa%2C%20followed%20by%20South%20America.">carbon emissions</a>. Restoring these areas and monitoring subterranean life can help reduce carbon emissions and improve our ability to reduce the effects of a changing climate.</p>
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Read more:
<a href="https://theconversation.com/no-more-excuses-restoring-nature-is-not-a-silver-bullet-for-global-warming-we-must-cut-emissions-outright-186048">No more excuses: restoring nature is not a silver bullet for global warming, we must cut emissions outright</a>
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<h2>It’s still an emerging science</h2>
<p>The use of ecoacoustics in restoration efforts is still relatively new, but it’s an important step towards a more holistic and effective approach to ecosystem recovery. By embracing new technologies and approaches, we can work towards a healthier and more sustainable planet.</p>
<p>Of course, there are challenges we still have to overcome. For instance, accurately identifying the sources of acoustic signals in a complex soundscape can be challenging. However, as technologies and methods continue to improve, the potential benefits of ecoacoustics are immense.</p>
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<img alt="" src="https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525048/original/file-20230509-23-oxr0m9.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">
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<span class="caption">When a forest like this temperate woodland in the UK is healthy, it acts as a carbon sink.</span>
<span class="attribution"><a class="source" href="https://pixabay.com/photos/bluebell-woods-bluebells-oak-forest-5069304/">Pixabay</a></span>
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<p>By monitoring life underground in a non-intrusive and efficient way, we can better understand the effectiveness of our restoration efforts. This will help us make more informed decisions about how to protect nature. </p>
<p>We’ve only just begun to scratch the surface when it comes to the possibilities of ecoacoustics in restoration efforts. It’s an exciting time for those working in this field, as we discover new ways to use sound to heal our planet.</p>
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Read more:
<a href="https://theconversation.com/soil-abounds-with-life-and-supports-all-life-above-it-but-australian-soils-need-urgent-repair-187280">Soil abounds with life – and supports all life above it. But Australian soils need urgent repair</a>
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<p class="fine-print"><em><span>Jake M Robinson is affiliated with the UNFCCC Resilience Frontiers think tank. </span></em></p><p class="fine-print"><em><span>Carlos Abrahams works for Baker Consultants, an ecological consultancy that specialises in ecoacoustics. He currently receives research funding from the UK Government.</span></em></p><p class="fine-print"><em><span>Martin Breed receives funding from the Australian Research Council, Cooperative Research Centre for Transformations in Mining Economies (CRC TiME), Australian Academy of Science, and New Zealand Ministry of Business, Innovation & Employment.</span></em></p>Acoustic technology allows us to listen to the sounds produced by the creatures in forest soils. A new study shows it’s a reliable way to monitor the biodiversity and health of the soil and forest.Jake M Robinson, Ecologist and Researcher, Flinders UniversityCarlos Abrahams, Senior Lecturer in Environmental Biology - Director of Bioacoustics, Nottingham Trent UniversityMartin Breed, Associate Professor in Biology, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1980902023-01-19T06:11:41Z2023-01-19T06:11:41ZOffshore wind farm construction is noisy – but gadgets used to protect marine mammals are working<figure><img src="https://images.theconversation.com/files/505122/original/file-20230118-22-euadqv.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4595%2C3061&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Harbour porpoises are the most common toothed whale in the turbine-rich North Sea.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/harbour-porpoise-phocoena-2137783321">Onutancu/Shutterstock</a></span></figcaption></figure><p><a href="https://energy.ec.europa.eu/topics/renewable-energy/offshore-renewable-energy_en#:%7E:text=The%20deployment%20of%20offshore%20wind,the%205%20EU%20sea%20basins.">The European Union</a> had 14.6 gigawatts (GW) of offshore wind energy installed in 2021, and this is projected to increase by at least 25 times in the next ten years. While an expanding renewable energy sector is necessary to replace fossil fuels and slow climate change, it must not come at a cost to <a href="https://theconversation.com/uk/topics/biodiversity-486">Earth’s embattled wildlife</a>. </p>
<p>To date, most offshore wind turbines have been built using fixed foundations, typically steel piles that are driven into the seabed with hydraulic hammers – often very large ones. The noise that pile-driving generates can be heard tens of kilometres from the source as short and sharp concussions like gunfire.</p>
<p>Sound travels much more efficiently in water than in air. Marine mammals like whales and porpoises use it to communicate over long distances, sense the environment and locate prey. This dependence on sound makes marine mammals <a href="https://doi.org/10.1644/07-MAMM-S-307R.1">particularly vulnerable</a> to the effects of man-made noise, including the noisy construction of offshore wind farms. Pile-driving can deafen, injure or even kill marine mammals at close range.</p>
<p>The harbour porpoise is the smallest and <a href="https://www.frontiersin.org/articles/10.3389/fmars.2020.606609">most common</a> species of cetacean in the North Sea, where EU countries hope to generate <a href="https://windeurope.org/policy/joint-statements/the-esbjerg-offshore-wind-declaration/">150 GW</a> of offshore wind energy by 2050. Like bats, these relatives of whales and dolphins emit clicks to echolocate almost continuously. This helps them find and identify objects, including food. Acoustic deterrents, small devices which emit pulses of sound, are used to scare marine mammals away from where wind farms are being built to protect them from the noise generated by pile-driving. Until recently though, no one was sure how well these deterrents worked.</p>
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<img alt="The dorsal fins and backs of two harbour porpoises emerging from the water." src="https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505126/original/file-20230118-14-1r7n63.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">
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<span class="caption">Harbour porpoises, as the name suggests, are found in coastal waters.</span>
<span class="attribution"><span class="source">University of Aberdeen</span>, <span class="license">Author provided</span></span>
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<p>My colleagues at the University of Aberdeen’s Lighthouse Field Station and the University of St. Andrews’ Sea Mammal Research Unit developed <a href="https://doi.org/10.1098/rsbl.2022.0101">a portable acoustic recorder</a> which can detect the movements of harbour porpoises. Using an array of these recorders during pile-driving at an offshore wind farm in north-east Scotland, we showed that acoustic deterrents work – porpoises swim directly away from the pulses of sound, ameliorating the most severe impacts of construction at sea. </p>
<h2>Fighting noise with noise</h2>
<p>A range of <a href="https://doi.org/10.3390/jmse9080819">measures</a> have been deployed to minimise the harm from offshore wind farm construction. Acoustic deterrent devices, which are switched on before pile-driving begins, are supposed to empty the sea of marine mammals tens to hundreds of metres around the construction site, where the noise is expected to be most damaging. These <a href="https://doi.org/10.3354/meps10482">electronic devices</a> were originally developed for use in the aquaculture industry to deter seals from fish farms.</p>
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<img alt="A wind turbine on a yellow platform in the ocean." src="https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505128/original/file-20230118-22-rpeyaq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&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">Offshore wind turbine foundations are driven into the seabed.</span>
<span class="attribution"><span class="source">University of Aberdeen</span>, <span class="license">Author provided</span></span>
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<p>Despite <a href="https://doi.org/10.3354/MEPS10100">experimental trials</a>, there is limited evidence to show how well acoustic deterrents work during construction. This is, at least in part, due to the difficulties of working in the marine environment, but also because of the challenges involved in studying animals that are highly mobile, relatively rare and live most of their lives underwater and out of sight. These factors make it very hard to observe how marine mammals react to particular noises or disturbances. Fortunately, we were able to turn the dependence of harbour porpoises on sound to our advantage.</p>
<p>Recent advances in <a href="http://dx.doi.org/10.1371/journal.pone.0229058">passive acoustic monitoring</a> meant that we could use a sound recorder connected to a small cluster of underwater microphones, called hydrophones, to study porpoise movements. By measuring tiny differences in the time of arrival of porpoise echolocation clicks at the four hydrophones, we identified the direction from which they were echolocating. The harbour porpoise’s echolocation beam is <a href="https://doi.org/10.1121/10.0001376">narrow and forward-facing</a>, and so from these findings, we were able to determine the direction in which they were swimming.</p>
<figure class="align-center ">
<img alt="A drum covered in electronic devices is lowered over the side of a boat into the ocean." src="https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505120/original/file-20230118-20-8vvg3x.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 hydrophone cluster being deployed.</span>
<span class="attribution"><span class="source">University of Aberdeen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We found that when acoustic deterrents were in use, the clicks of harbour porpoises we detected indicated they were swimming directly away from the construction site. This proves that acoustic deterrent devices can make offshore wind farm construction safer. </p>
<p>We did detect responses among harbour porpoises up to 7 km from the construction site, suggesting that these deterrent devices may be almost too good at their job. Such a long-distance effect could displace animals from important feeding sites and highlights the importance of a balance between preventing injuries and minimising disturbance.</p>
<p>Our portable acoustic recorder can now improve protection for marine mammals by more accurately determining how they respond to disturbance across a wide range of habitats. It will also allow researchers to gauge the effectiveness of measures used to minimise disturbance during wind farm construction or other activities, including animal deterrents and systems for reducing the noise produced by piling at construction sites.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?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">
<figcaption>
<span class="caption"></span>
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<hr><img src="https://counter.theconversation.com/content/198090/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isla Graham received funding from Moray Offshore Wind Farm (East) Ltd. The funding body had no input in data collection, data analysis or interpretation. The aims, scope and experimental design of the study were developed by the authors to meet Moray Offshore Wind Farm (East) Ltd planning consent conditions. These were agreed by the regulator Marine Scotland Licensing and Operations Team following consultation with statutory advisors represented on the Moray Firth Regional Advisory Group (MFRAG), a stakeholder group that was established by the Scottish government to oversee the monitoring programme.</span></em></p>A new acoustic recorder could track the movements of marine mammals more accurately.Isla Graham, Research Fellow, School of Biological Sciences, University of AberdeenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1643682021-07-14T12:52:22Z2021-07-14T12:52:22ZRumble in the jungle: an ear to the ground can tell us how elephants are faring in the wild<figure><img src="https://images.theconversation.com/files/411108/original/file-20210713-23-mlrrqx.png?ixlib=rb-1.1.0&rect=0%2C0%2C2830%2C1888&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rumbles elephants make travel through the air and the ground.</span> <span class="attribution"><span class="source">Beth Mortimer</span>, <span class="license">Author provided</span></span></figcaption></figure><p>African elephants can be found roaming the forests and grasslands of 37 countries across the continent. But sadly, these sentient and intelligent animals are rapidly declining, and were <a href="https://www.iucn.org/news/species/202103/african-elephant-species-now-endangered-and-critically-endangered-iucn-red-list">recently declared endangered</a>. </p>
<p>For these remaining elephants to find each other, they make a variety of vocal noises to greet and warn each other, or to woo potential mates. Some of their vocalisations, which are called rumbles, are very low-pitched. So low in fact that humans can barely hear them. Due to the firm stance and weight of the elephants (which can reach 6,000kg), these waves travel not only through the air but also into the ground.</p>
<p>Elephants are thought to communicate over large distances – <a href="https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.530.8940&rep=rep1&type=pdf">up to several kilometres</a> in some cases. But it hasn’t been clear to scientists how important the seismic vibrations of their rumbles are in these long-distance chats. Is it just a coincidence that these sounds travel so far through the ground? Or is it something elephants actively exploit to stay in touch? </p>
<p><a href="http://rsif.royalsocietypublishing.org/doi/10.1098/rsif.2021.0264">We wanted to</a> find out. By deciphering the hidden information in these rumbles, we hoped they might also help us study and track elephants in future.</p>
<h2>Pinpointing elephants</h2>
<p>Working at Mpala Research Center in Kenya with computer scientists, earth scientists, conservationists and biologists, we set up microphones and seismometers around a watering hole known to be frequented by elephants. Seismometers pick up small underground vibrations and are typically used to measure earthquakes and explosions, some of which can be detected on the other side of the globe.</p>
<figure class="align-center ">
<img alt="A herd of elephants departing a lake." src="https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411211/original/file-20210714-21-hb6rlw.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">On the move: a herd of elephants leaving the watering hole.</span>
<span class="attribution"><span class="source">Beth Mortimer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For the first time ever, we found it was possible to accurately locate elephants by measuring vibrations in the ground caused by their low-pitched rumbles. Our devices recorded the rumbles they made at distances of up to 500 metres. </p>
<p>Comparing the signals at all the seismometers, we could estimate the animal’s location with an average accuracy of just a few metres. Surprisingly, the seismic sensors were slightly more accurate in pinpointing the elephants than the microphones. It’s quite common for scientists to track species using acoustic technology, but getting better results with signals through the ground could open a new way of monitoring wildlife.</p>
<h2>The future of wildlife monitoring</h2>
<p>It’s unknown how exactly elephants pick up these vibrations and how they decipher their meaning. But our study suggests that the seismic rumbles could announce the location of the vocalising animal to other elephants far away, despite the thick layers of earth that these waves pass through. </p>
<p>Whereas sound recordings can be interrupted by rain, wind and trees, seismic monitoring is relatively free of these types of interference. Where acoustic monitoring fails or gives bad results, seismic monitoring could be used instead. </p>
<p>This is helpful, as it’s important to know whether or not elephants are present in protected areas, or if they’ve wandered into places where they might be in danger, such as unguarded territories or towns and villages. Knowing this could allow rangers to respond quicker and prevent poaching, as well as prevent other kinds of conflict erupting between elephants and people.</p>
<figure class="align-center ">
<img alt="A large elephant amid African scrubland." src="https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411212/original/file-20210714-27-1i8szsp.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">Elephants can sometimes wander into trouble.</span>
<span class="attribution"><span class="source">Beth Mortimer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Seismic monitoring could even be used to monitor hoofed animals like endangered species of giraffe and zebras. The seismic vibrations of their footsteps could help scientists study their group behaviour and how these species interact with their environment, without needing to tag them.</p>
<p><a href="https://doi.org/10.1016/j.cub.2018.03.062">Previous work</a> has shown that seismic recordings can accurately differentiate between the sounds made by elephants walking and their vocalisations. In future work, we hope to use this to develop AI algorithms that can detect what kind of wildlife is passing close to these sensors and what they are up to. This could help us monitor threatened or endangered species, count populations, and learn more about their movement and fascinating social behaviours.</p><img src="https://counter.theconversation.com/content/164368/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 organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>African elephants stay in touch over large distances. We found out how.Michael Reinwald, Postdoctoral Research Associate in Zoology, University of OxfordBeth Mortimer, Royal Society University Research Fellow of Zoology, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/960862018-07-13T10:24:32Z2018-07-13T10:24:32ZScientist at work: Identifying individual gray wolves by their howls<figure><img src="https://images.theconversation.com/files/227222/original/file-20180711-27015-1dr73z1.jpg?ixlib=rb-1.1.0&rect=164%2C226%2C2079%2C1483&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Each wolf calls with its own 'voice.'</span> <span class="attribution"><span class="source">Angela Dassow</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Love them or hate them, wolves are vital members of natural ecosystems and the health of a wolf population can be an important factor in <a href="https://www.livingwithwolves.org/about-wolves/why-wolves-matter/">maintaining balance</a> among species. Wolf populations are growing in North America – the Great Lakes region in particular now supports over <a href="https://www.fws.gov/midwest/wolf/aboutwolves/wolfpopus.htm">3,700 individuals</a>. Keeping track of wolf pack movements is important for reducing human-wolf conflicts which can arise when packs move too close to ranches.</p>
<p>The traditional way to track wolves involves setting traps, sedating and then radio-collaring individual animals. While effective, this approach is time intensive and expensive, and entails risks for the animals. </p>
<p>I was fortunate to participate in this entire process firsthand as an undergraduate student. During the summer trapping seasons, I became familiar with each of the wolves in the central forest region of Wisconsin. This experience led to several conversations with the wildlife biologists in the area about whether wolf howls could be used to help identifying non-radio-collared pack members.</p>
<p><audio preload="metadata" controls="controls" data-duration="5" data-image="" data-title="Howl from a wild adult wolf, recorded in central Wisconsin by author Angela Dassow and Carthage College biology students, Cara Hull and Caitlin McCombe." data-size="119400" data-source="" data-source-url="" data-license="Author provided" data-license-url="">
<source src="https://cdn.theconversation.com/audio/1199/south-bluff-filtered-howl.mp3" type="audio/mpeg">
</audio>
<div class="audio-player-caption">
Howl from a wild adult wolf, recorded in central Wisconsin by author Angela Dassow and Carthage College biology students, Cara Hull and Caitlin McCombe.
<span class="attribution"><span class="license">Author provided</span><span class="download"><span>117 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1199/south-bluff-filtered-howl.mp3">(download)</a></span></span>
</div></p>
<p>This question remained a fun thought experiment for many years. Now <a href="https://www.carthage.edu/live/profiles/1488-angela-dassow">as a biology professor</a> who specializes in <a href="http://ocr.org/learn/bioacoustics/">bioacoustics</a>, I’ve been able to turn that thought experiment into a full research question: Can we use acoustic features to identify individual wolves in the wild? </p>
<h2>Downsides of radio collaring</h2>
<p>Because of the many challenges involved in radio collaring an animal, it would be useful to have a new way to identify and track wild wolves.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=568&fit=crop&dpr=1 600w, https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=568&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=568&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=714&fit=crop&dpr=1 754w, https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=714&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/227472/original/file-20180712-27024-1pztro3.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 U.S. Fish and Wildlife Service employee fastens a radio collar onto a sedated female gray wolf.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/usfwsmtnprairie/8488974469">Lori Iverson/USFWS</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>To successfully set a trap, wildlife managers must first spend days, if not weeks, scouting for signs of wolves. Once they’ve identified a suitable area, they set traps that must be checked every 24 hours. If successful, the animal needs to be sedated before it can be removed from the trap – which can be stressful both for the wolf and the researchers involved.</p>
<p>A sedated wolf cannot regulate its body temperature and overheating can become an issue on hot days. Human handling of a sedated wolf can also be stressful on the pack members that are often nearby, observing the scene. Even after an animal is successfully radio-collared and released, it’s still vulnerable to predators while the sedative wears off.</p>
<p>In spite of these risks, radio-collaring has been the standard way to track populations because each collar’s radio-transmitter frequency acts as a unique identifier of an individual. Researchers can then use aerial surveys where a pilot searches for the collared animal or ground surveys where a field crew drives throughout a pack territory searching for feedback from the radio signal. This method is used to track a wide array of animals, including turtles, birds, bats, whales, fish, snakes and more.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223229/original/file-20180614-32319-1juwm5r.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">Angela Dassow and Cara Hull survey a road in central Wisconsin for signs of wolves.</span>
<span class="attribution"><span class="source">Caitlin McCombe</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Listening to learn who’s who</h2>
<p>In 2013, behavioral ecologist <a href="https://scholar.google.com/citations?user=CZyS1lMAAAAJ&hl=en&oi=sra">Holly Root-Gutteridge</a> and her colleagues successfully demonstrated that they could <a href="https://doi.org/10.1080/09524622.2013.817318">identify individual wolves in captivity using acoustic features</a>. Their research provided evidence that it made sense to test whether vocal identification in wild animals is possible.</p>
<p>So with the support of the <a href="https://www.carthage.edu/sure/">Summer Undergraduate Research Experience</a> at <a href="https://www.carthage.edu/">Carthage College</a>, volunteers from the <a href="http://www.timberwolfinformation.org/">Timber Wolf Information Network</a>, and wildlife managers at <a href="https://dnr.wi.gov/topic/lands/wildlifeareas/sandhill/">Sandhill Wildlife Area</a> in Babcock, Wisconsin, my undergraduate students Cara Hull and Caitlin McCombe and I began to record wolves in the wild.</p>
<p>It would be an understatement to say fieldwork can be challenging. On any given day, there can be daunting weather fluctuations. Biting insects, especially mosquitoes and deer flies, are abundant in wolf habitat. We had to constantly check ourselves for ticks. And then of course comes the actual fieldwork. </p>
<p>Wolves naturally avoid coming near people, but the best quality recordings are made up close to where the animals are producing the sounds. To get close with our audio equipment, we had to track the wolves every day to learn where they’d most recently been within their large territories. That’s how we’d establish a starting point for our nightly recording sessions.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=765&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=765&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=765&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=962&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=962&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223228/original/file-20180614-32304-mgakkr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=962&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fresh track from an adult gray wolf.</span>
<span class="attribution"><span class="source">Angela Dassow</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Conducting a daily survey of wolf habitat requires driving or walking down every possible path within a wolf’s territory. Signs of activity could include fresh footprints or tracks. This can tell us how many animals were in the area and what direction they were heading.</p>
<p>Large dogs can produce footprints that are similar in size to those of wolves; but the pattern of tracks can be distinguished based on the placement of their feet and the directness of the chosen route. Dogs have a tendency to wander more, while wolves will walk in a more efficient straight line.</p>
<p>In addition to tracks, we conduct a survey of fresh scat. It’s not glamorous, but examining their feces provides valuable information about what the wolves have been eating and how recently they walked along a trail.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223050/original/file-20180613-32323-8i1dwh.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">Carthage College biology students Cara Hull and Caitlin McCombe conduct a howl survey in central Wisconsin.</span>
<span class="attribution"><span class="source">Angela Dassow</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Using the information from our daytime survey, we plan a shorter nighttime howling route. Howling is a natural behavior during the evenings, when wolves call to signal that a territory is occupied. At each stopping point on our route, a researcher must get out of the vehicle and howl while another researcher records with a microphone any wolf responses, announcing their presence or defending territory. If we are successful in eliciting a response, we continue in its direction until we get as close as possible.</p>
<p>Use of lights is discouraged since it can deter the wolves from calling again, so we needed to feel our way through the forest at night. Personally, I think it is incredibly exciting to be walking down a trail in the dark and have a wolf walk within feet of where I am. It may sound scary, but we are not in any danger since wolves prefer to avoid contact with humans. During our month-long survey, we were fortunate to experience two close wolf encounters. </p>
<h2>Back in the lab, analyzing the calls</h2>
<p>With the howls recorded, we can return to the lab to analyze our findings using audio software.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223230/original/file-20180614-32316-16wyrn2.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">Acoustic properties are measured using Adobe Audition.</span>
<span class="attribution"><span class="source">Angela Dassow</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We were able to isolate 21 howls from two adult wolves over two evenings. For each howl, we made six types of frequency measurements and two types of duration measurements. Frequency is how high or low the pitch of the howl sounds and duration is the length of time the howl lasted.</p>
<p>For wild gray wolves, we found that the maximum frequency – that is, the highest sound an animal produced – and the frequency at the end of the howl were the two variables that were most individualistic. For captive wolves, it was different. The lowest frequency an individual produced – what in acoustics is called their fundamental frequency – and the loudness of its calls were the factors that best differentiated among the captive individuals.</p>
<p>The differences in useful identification information between wild and captive howls are likely a reflection of signal quality. The captive recordings are much clearer than what we were able to record in the wild, where we were typically at least half a mile away from the wolves; the signal degrades with distance. As signal quality declines, maximum frequency and end frequency become more useful in individual identification.</p>
<p>Based on our findings and previous research, it is possible to monitor gray wolf populations using non-invasive methods. To do so effectively, researchers would need to record known individuals in a particular area. Once they’ve built up a database of known individuals’ howls, they can conduct nightly surveys. Comparing new recordings to those in the audio library would let them determine which individuals are in an area. </p>
<p>While radio-collaring procedures may still be useful in some cases, vocal identification is a promising alternative for monitoring individuals. Acoustic surveys are still a time-consuming process, but they eliminate the time needed to trap individuals and remove any possibility of accidentally injuring an animal in a trap. Additionally, once researchers gather a database of positively identified individuals, they can use remote monitoring stations to record howls, thus reducing the amount of time spent conducting nightly surveys. Acoustic monitoring could potentially track all the wolves in multiple packs whereas radio-collaring is typically used to track a single member in select packs.</p><img src="https://counter.theconversation.com/content/96086/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Angela Dassow 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>Tracking wild animals can provide lots of valuable data. New research suggests audio recordings of wild wolves can replace the typical radio collars, which can be expensive and intrusive.Angela Dassow, Assistant Professor of Biology, Carthage CollegeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/733972017-02-22T16:32:58Z2017-02-22T16:32:58ZWhy conservation scientists are listening to nature<figure><img src="https://images.theconversation.com/files/157889/original/image-20170222-1316-35ii98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Pedro A. Estevez Calzado / shutterstock</span></span></figcaption></figure><p>The world is noisy. </p>
<p>In cities, we find ourselves constantly surrounded by the moan of motors, the screech of sirens, and the prattle of people. So much so, that we often crave the peace and quiet of the countryside. </p>
<p>But silence is hard to find, even in nature. Animals chirp, roar, squeak, squawk, and howl to attract mates, defend territories, locate prey or even just find their way around. Wind whistles, rain hammers and streams gurgle. The sea thunders. Even under the water’s surface, a cacophony of unknown snaps, boings, ripples and other melodies still surround you. </p>
<p>Together, this symphony is the natural <a href="https://academic.oup.com/bioscience/article/61/3/203/238162/Soundscape-Ecology-The-Science-of-Sound-in-the">soundscape</a>. </p>
<p>Scientists can use acoustic sensors to monitor anything from an entire soundscape all the way down to a single species. Acoustic monitoring has helped us learn more about the behaviour and ecology of animals such as whales, dolphins, birds, amphibians, insects and bats. </p>
<p>Bats, the subject of my own research, are ideal candidates for acoustic monitoring. Famously, they use echolocation to navigate through the skies, but they also produce <a href="https://www.werc.usgs.gov/oldsitedata/bats/feedingbuzz.html">feeding buzzes</a> to hunt down prey, and social calls to attract mates. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/DsI14j9JB2c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The bat’s sonar shortens into a ‘feeding buzz’ as it closes in on an insect.</span></figcaption>
</figure>
<p>Monitoring the distinct calls bats use for navigation, prey location and socialising allows us to determine where they are and what they are using particular habitats for. Sensors are often placed outside roosts, along suspected commuting routes and in foraging locations. Currently sensors are too large to be attached to the bats themselves.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157907/original/image-20170222-6440-1eshcq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of the author’s acoustic bat-recorders.</span>
<span class="attribution"><span class="source">Ella Browning</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Studies using acoustic sensors have furthered our knowledge of how these animals are responding to pressures such as climate change and habitat loss. The UK’s <a href="http://www.bats.org.uk/pages/nbmp.html">National Bat Monitoring Program</a> – a citizen science project that has been running since 1997 – relies on volunteers across the country armed with bat detectors to carry out annual acoustic surveys. This <a href="http://www.sciencedirect.com/science/article/pii/S0006320714004479">valuable data</a> has revealed some promising population increases of many threatened bat species. </p>
<h2>Listening to the landscape</h2>
<p>Zooming out from individual species, a new field of research has recently emerged called <a href="http://link.springer.com/article/10.1007/s10980-011-9600-8">soundscape ecology</a>. This is the study of the entire collection of sounds that are emitted from a landscape. Scientists group these sounds into those created by humans (known as anthrophony), those emitted by plants and animals (biophony), and natural but non-biological sounds like rain wind and waves (geophony).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157906/original/image-20170222-6448-1uq9uhw.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">Thanks to acoustic monitoring, we know UK population of lesser horseshoe bats is growing.</span>
<span class="attribution"><span class="source">All-stock-photos / shutterstock</span></span>
</figcaption>
</figure>
<p>Humans often don’t consider sound as an important part of an ecosystem, but other animals are not so oblivious. For instance, the tiny larvae of reef fish use the clamour of <a href="https://www.ncbi.nlm.nih.gov/pubmed/16905427">fish and crustaceans calls from coral reefs</a> to determine which one they should grow up on. And just as the ambient sound can tell the larvae about the health of a reef, we can also use sound as a way to monitor the status of the environment.</p>
<p>As microphones get smaller, cheaper and better at storing data, they are becoming an ever more viable tool for a variety of conservation projects. Acoustic sensors are particularly effective in remote environments where access is limited, and have huge potential for monitoring illegal poaching. In Cameroon’s Korup National Park, where monkeys and chimpanzees are targeted for bushmeat, sensors have already been successfully used to identify target areas for anti-poaching patrols, by <a href="https://bioacousticmonitoring.wordpress.com/">recording the location of gunshots and animal calls</a>.</p>
<p>Similarly, acoustic sensors may be valuable for monitoring illegal <a href="https://figshare.com/articles/Acoustic_Monitoring_of_Blast_Fishing_Pilot_Study/1003978">blast fishing</a> in the sea, where dynamite is dropped into the water and the explosion stuns or kills everything in range. This form of fishing has a horrific impact on ocean ecosystems, decimating fragile corals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157890/original/image-20170222-1350-cemxzj.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 impact of blast fishing on a coral reef in Indonesia.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/silkebaron/930351113">prilfish</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>These aren’t real-time reporting systems, for now – the data must be collected and analysed to identify particular sounds. However, with the technology rapidly advancing, automatic detection systems may be possible in the not too distant future, enabling real-time reporting of illegal poaching or fishing.</p>
<p>With biodiversity in decline globally, acoustic monitoring is a highly-effective, efficient and low-cost way to gather the data required to prevent further losses. In the future, we may have huge networks of acoustic sensors monitoring the natural world, feeding us live information. We humans are highly visual animals, but we should remember to take the time to close our eyes and open our ears to the orchestra of the natural world around us.</p><img src="https://counter.theconversation.com/content/73397/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ella Browning receives funding from NERC</span></em></p>‘Acoustic monitoring’ can help us protect animals and their habitats.Ella Browning, PhD Researcher in Bat Ecology, UCLLicensed as Creative Commons – attribution, no derivatives.