tag:theconversation.com,2011:/ca/topics/animal-sounds-34035/articlesanimal sounds – The Conversation2023-06-22T12:30:35Ztag:theconversation.com,2011:article/2081532023-06-22T12:30:35Z2023-06-22T12:30:35ZTo see how smoke affects endangered orangutans, we studied their voices during and after massive Indonesian wildfires<figure><img src="https://images.theconversation.com/files/533199/original/file-20230621-11493-h6xfhj.jpeg?ixlib=rb-1.1.0&rect=7%2C0%2C4861%2C3080&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An adult male orangutan contemplates his next move in haze produced by Indonesia's 2015 wildfires.</span> <span class="attribution"><span class="source">Wendy Erb</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Bornean orangutans are one of three orangutan species, all <a href="https://www.iucnredlist.org/search?query=orangutan&searchType=species">critically endangered</a>. They thrive in carbon-rich peat swamp forests on the Indonesian island of Borneo. These habitats are also the sites of massive wildfires.</p>
<p>Indonesian wildfires in 2015 caused some of the <a href="https://doi.org/10.3390/rs10040495">worst fire-driven air pollution</a> ever recorded. The fires were driven by an <a href="https://www.noaa.gov/understanding-el-nino#">El Niño climatic cycle</a>, which <a href="https://www.nasa.gov/feature/Goddard/2016/severe-2015-indonesian-fire-season-linked-to-el-nino-drought">caused especially dry weather</a> in the region.</p>
<p>Compared to other wildfires, peatland fires smolder underground and produce exceptionally high levels of hazardous gases and particulate matter – a leading cause of <a href="https://theconversation.com/wildfire-smoke-can-harm-human-health-even-when-the-fire-is-hundreds-of-miles-away-a-toxicologist-explains-why-206057">global pollution-related deaths and illnesses</a>. </p>
<p>Orangutans are well known as an “<a href="https://www.britannica.com/science/indicator-species">indicator species</a>” – one that can serve as a proxy for the health of an ecosystem. Changes in their environments often cause conspicuous changes in the apes’ health and behavior. Frequent and persistent exposure to toxic smoke could have severe consequences for orangutans and other wildlife.</p>
<p>Toxic air pollution also poses serious health and safety risks for researchers. However, <a href="https://doi.org/10.1093/biosci/biy147">remote sensing techniques</a>, such as satellite images, GPS data and acoustic monitoring, are increasingly popular ways to track wildlife populations and see how creatures respond to changes in their environments.</p>
<p>I have studied the behavior, ecology and acoustic communication of <a href="https://scholar.google.com/citations?user=ykHYzwEAAAAJ&hl=en">wild primates in Indonesia</a> since 2005. In a new study, my co-authors and I investigated how wild orangutans in Borneo were affected by toxic emissions from Indonesia’s 2015 peatland wildfires – by <a href="https://doi.org/10.1016/j.isci.2023.107088">studying their voices</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/cBnbLJ5TzvE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Indonesia’s degraded peatlands are tinderboxes that can easily ignite with several weeks of dry weather.</span></figcaption>
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<h2>Smoke exposure poses long-term risks</h2>
<p>Around the world, <a href="https://www.unep.org/news-and-stories/press-release/number-wildfires-rise-50-2100-and-governments-are-not-prepared">wildfires are on the rise</a>. They often produce a thick blanket of haze that contains diverse hazardous gases and particulate matter, or PM. Most recently, smoke from Canadian wildfires blanketed the U.S. East Coast and Midwest in early June 2023, <a href="https://www.youtube.com/watch?v=kLN3kBthm9Y">turning skies orange</a> and triggering public health alerts.</p>
<p>Studies have shown that <a href="https://doi.org/10.1016/j.envres.2014.10.015">human health risks from wildfire smoke</a> include respiratory and cardiovascular illnesses, systemic inflammation and premature death. Much less is known about how smoke affects wildlife, but in a pair of studies published <a href="https://doi.org/10.1016/j.reprotox.2021.08.005">in 2021</a> <a href="https://doi.org/10.1038/s41467-022-29436-9">and 2022</a>, scientists at the <a href="https://cnprc.ucdavis.edu/">California National Primate Research Center</a> reported alarming findings.</p>
<p>After less than two weeks of exposure to high concentrations of particulate matter – in particular, ultrafine particles measuring less than 2.5 microns in diameter, which are known as PM2.5 – captive <a href="https://www.britannica.com/animal/rhesus-monkey">rhesus macaques</a> suffered a spike in pregnancy loss. What’s more, surviving fetuses and infants suffered long-term effects on lung capacity, immune responses, inflammation, cortisol levels, behavior and memory. </p>
<p>During Indonesia’s 2015 fires, Borneo’s air had particulate matter concentrations nearly an order of magnitude higher than the levels in these studies. This made the potential implications for people and wildlife who gasped through Indonesia’s wildfire smoke for nearly two months extremely worrying.</p>
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<a href="https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Fire and smoke rise from charred ground near a scorched tree." src="https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533205/original/file-20230621-17-x1066c.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&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 wildfire blazes in a small rubber tree garden along the border of the Tuanan study area during Indonesia’s 2015 wildfires.</span>
<span class="attribution"><span class="source">Wendy Erb</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Orangutans in the haze</h2>
<p>I was studying wild orangutans in the forests of Indonesian Borneo when the 2015 fires started. My colleagues and I at the <a href="https://coreborneo.com/tuanan-research-station/">Tuanan Orangutan Research Station</a> tracked local fires and patrolled nearby hot spots to assess the risk of fire spreading to our research area. </p>
<p>Wearing N-95 masks, we continued to monitor orangutans in hopes of learning how the animals were coping with encroaching fires and thick smoke. A few weeks into the fire season, I noticed a difference in the sound of the males’ “<a href="https://wildambience.com/wildlife-sounds/orangutan/">long call</a>,” which was the focus of <a href="https://wendyerb.weebly.com/projects.html">my research</a>. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/cRJoooWf5vU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An adult male Bornean orangutan’s long call.</span></figcaption>
</figure>
<p>Long calls are booming vocalizations that can be heard over distances of more than half a mile (1 kilometer). Orangutans are semi-solitary and live in dispersed communities, so these calls serve an important social role. Adult males make them to advertise their prowess to listening females in the area and to scare off any eavesdropping rival males. A couple of weeks after the smoke had appeared, I thought these males sounded raggedy – a little like humans who smoke a lot. </p>
<p>We observed the orangutans for 44 days during the fires, until large blazes encroached on our study area. At that point, we stopped the study to help extinguish the blazes with local firefighting teams and other government and nonprofit groups. Fires burned in our study area for three weeks.</p>
<p>Using data that we collected before, during and after the fires, I led an analysis of this Bornean orangutan population’s <a href="https://doi.org/10.1016/j.isci.2023.107088">behavior and health</a>. My co-authors and I found that in the weeks after the fires, the apes reduced their activities – resting more and traveling shorter distances – and consumed more calories than normal. </p>
<p>But although they were eating more and moving less, we found by collecting and testing the apes’ urine that they were <a href="https://doi.org/10.1038/s41598-018-25847-1">still burning stored fat</a> – a sign that they somehow were using up more energy. We hypothesized that the cause <a href="https://my.clevelandclinic.org/health/symptoms/21660-inflammation#:%7E:text=The%20most%20common%20reasons%20for,from%20an%20infection%20or%20injury">might be inflammation</a> – the swelling, fever, pain and fatigue that human and animal bodies experience in response to infection or injury. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An orangutan reclines in a tree surrounded by haze." src="https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=380&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=380&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=380&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533206/original/file-20230621-20-pixdob.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Otto, one of four adult male orangutans observed and recorded for this research, takes a midday smoky nap during Indonesia’s 2015 wildfires.</span>
<span class="attribution"><span class="source">Wendy Erb</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Sentinel sounds</h2>
<p>Studies have shown that when humans are exposed to particulate matter, they can experience inflammation, both in their <a href="https://doi.org/10.1097/JOM.0000000000001775">respiratory tracts</a> and <a href="https://doi.org/10.1164/ajrccm.164.5.2010160">throughout their bodies</a>. We wanted to know whether inhaling wildfire smoke would cause vocal changes in orangutans, just as inhaling cigarette smoke does in humans.</p>
<p>For this study, my co-authors and I carefully analyzed more than 100 sound recordings of four male orangutans that we followed before and during the fires to measure their vocal responses to wildfire smoke. Research has shown that a suite of vocal features – including <a href="https://www.asha.org/practice-portal/clinical-topics/voice-disorders/#collapse_2">pitch, vocal harshness or hoarseness, and shaky voice</a> – reflects the underlying health and condition of both human and nonhuman animals. We were looking for acoustic clues about how this toxic air might be affecting the orangutans. </p>
<p>During the fires and for several weeks after the smoke cleared, these males called less frequently than usual. Normally, orangutans call about six times a day. But during the fires, their call rate was cut in half. Their voices dropped in pitch, showing more vocal harshness and irregularities. </p>
<p>Collectively, these features of vocal quality have been linked to inflammation, stress and disease – including COVID-19 – in <a href="https://doi.org/10.1016/j.eswa.2017.04.012">human</a> and <a href="https://doi.org/10.1038/s41598-021-83614-1">nonhuman</a> animals.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CCoXocEBgiv/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Listening to vocal species</h2>
<p>Increasingly frequent and prolonged exposure to toxic smoke could have severe consequences for orangutans and other animals. Our research highlights the urgent need to understand the long-term and far-ranging effects of peatland fires in Indonesia, which is one of the <a href="https://www.cbd.int/countries/profile/?country=id">most biodiverse countries in the world</a>. </p>
<p>By uncovering the linkages between acoustic, behavioral and energetic shifts in orangutans, our study highlights a way for scientists and wildlife managers to safely monitor the health of orangutans and other animals. Using <a href="https://www.birds.cornell.edu/ccb/passive-acoustic-monitoring/">passive acoustic monitoring</a> to study vocally active indicator species, like orangutans, could unlock critical insights into wildfire smoke’s effects on wildlife populations worldwide.</p><img src="https://counter.theconversation.com/content/208153/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Wendy M. Erb is affiliated with the American Society of Primatologists; the Borneo Nature Foundation; and Primate Conservation, Inc. She has received research funding from the American Association of University Women; the American Institute for Indonesian Studies; the American Association of Biological Anthropologists; the American Society of Primatologists; the British Academy; the Conservation, Food, and Health Foundation; Conservation International; Cornell University; Disney Conservation Fund; the Fulbright Program; the International Society of Primatologists; and the National Science Foundation. </span></em></p>Orangutans are vocal animals, so analyzing their calls during events like wildfires can indicate how smoke is affecting their health.Wendy M. Erb, Postdoctoral Associate in Conservation Bioacoustics, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2059792023-06-12T15:13:58Z2023-06-12T15:13:58ZWhy learning animal sounds can be crucial to children’s language development<figure><img src="https://images.theconversation.com/files/527852/original/file-20230523-29-v8py2u.jpg?ixlib=rb-1.1.0&rect=85%2C202%2C3629%2C2338&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">From an early age, children are able to recognize and respond to animal sounds. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Did you know that <a href="https://www.youtube.com/watch?v=75ENi5QC-vM">animal sounds</a> can be crucial to your child’s early speech and language development? Speech refers to the production <a href="https://www.peacehealth.org/medical-topics/id/hw265266#:%7E:text=Speech%20is%20making%20the%20sounds,and%20understanding%20what%20others%20say.">of sounds that transform into words through the physical act of speaking, and language encompasses</a> using words and gestures to communicate.</p>
<p>From the moo of a cow to the buzz of a mosquito, animal sounds offer fun and engaging ways for young children to <a href="https://doi.org/10.3389/fcomm.2021.709045">learn and practise speech and language skills</a>.</p>
<p>Children start developing their linguistic knowledge as young as six months of age. Among their <a href="https://doi.org/10.1111/desc.13066">first words</a> are often animal sounds.</p>
<p>Animal sounds provide an engaging way for children to develop <a href="https://www.icanteachmychild.com/animal-sounds/">cognitive skills</a> as well. So, if you want to support your child’s development, do not take animal sounds for granted. </p>
<h2>Understanding and expression</h2>
<p>Children’s <a href="https://www.healthlinkbc.ca/pregnancy-parenting/parenting-preschoolers-3-5-years/preschooler-growth-and-development/speech-0">speech and language skills</a> will shape their ability to understand others and express themselves.</p>
<p>While there are many ways to encourage speech and language development in children, one method is through animal sounds. Animal sounds can be used to promote communication development in all children, including those <a href="https://doi.org/10.1080/13682820310001625589">with speech and language difficulties</a>. </p>
<p>Some reasons for this: animal sounds are simple, repetitive and are sometimes a common part of children’s environments (such as through pets or books). From an early age, children are able to recognize and respond to animal sounds. These sounds provide a unique way to introduce children to new words and concepts and can help them associate sounds with specific animals. </p>
<figure class="align-center ">
<img alt="A baby next to a cat." src="https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527853/original/file-20230523-3417-wgx4ep.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">
<figcaption>
<span class="caption">Animal sounds can help children associate words with things they know in the world around them.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Because children like <a href="https://www.scholastic.com/parents/books-and-reading/raise-a-reader-blog/farm-animal-sounds.html">animals and are drawn to how they move and make sounds</a>, they are likely to be interested in words related to animals. </p>
<p>Imitating animal sounds can help children learn new vocabulary and <a href="https://speechblubs.com/blog/kids-animal-sounds/">speech skills</a>. It may also help children learn to use simple sentences such as “kitty meow” or “bee buzz.”</p>
<h2>Detecting speech-language challenges</h2>
<p>For all the aforementioned reasons, it is important for parents to understand the significance of animal sounds in early speech-language development. Parents can observe their children’s speech and language development to identify potential difficulties. </p>
<p>Observing early difficulties in children’s capacities to use and make animal sounds can be a way of detecting speech and language difficulties.</p>
<p>Some <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2491683/?report=printable">signs of speech and language difficulties in young children</a> include delayed speech, limited vocabulary, difficulty understanding questions and instructions, poor pronunciation of simpler sounds and words and difficulty combining words together after age two. </p>
<p>If parents think their children have difficulty in any of these areas, it is recommended they visit <a href="https://www.asha.org/public/who-are-speech-language-pathologists">a speech-language pathologist</a> as <a href="https://www.asha.org/public/speech/early-intervention/">early intervention</a> is crucial for promoting healthy communication skills.</p>
<figure class="align-center ">
<img alt="A mother reading a book to child." src="https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527854/original/file-20230523-27174-c2x3lt.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">Observing early difficulties in children’s capacities to make animal sounds can be a way of detecting speech and language difficulties.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Animal sounds in speech therapy</h2>
<p>If your baby is identified as having difficulty with speech or language, a <a href="https://nsuworks.nova.edu/ijahsp/vol17/iss3/1/">speech language pathologist may use animal sounds in different ways</a> to help them learn new sounds and words. </p>
<p>For example, speech language pathologists can use animal sounds like “woof” to help children practise making clear sounds. They can also use animal sounds to teach children the names and features of different animals, which can improve their vocabulary and knowledge of nature. </p>
<p>Speech language pathologists also play games that incorporate animal sounds to help young children learn to listen and pay attention to sounds. Incorporating animal sounds into games and activities can also make practice more fun and engaging for the child.</p>
<h2>Incorporating animal sounds</h2>
<p><a href="https://speechblubs.com/blog/animal-sounds-for-kids/">Parents can help</a> their children develop speech and language skills by using animal sounds in different ways. One way is to make animal sounds while playing or reading books together. </p>
<p>For example, when reading a book about farm animals, you can make the sound of a rooster or a sheep to help your child connect the sound to the animal. Another method is to play <a href="https://www.educagaming.com/en/gameDetail/guess-the-animal-sound-game/">animal sound-matching games</a>, where children match an animal sound to the corresponding picture. This can be a fun way for children to learn new words and sounds. </p>
<p>Parents can also take their children on nature walks or to the zoo to hear real animal sounds, which can help them develop a deeper understanding of their world.</p>
<h2>Foundation for speech, langauge development</h2>
<p>Animal sounds may seem like a simple part of children’s speech and language development, but they have much to offer and provide a fun and engaging way for children in learning and exploring the world. </p>
<p>Incorporating animal sounds into children’s learning routines can help them build a strong foundation for speech and language development that will serve them well as they grow and learn. </p>
<p>So, the next time you are playing with your child, do not forget to moo like a cow, ribbit like a frog or neigh like a horse. It could make a big difference in your child’s learning and development!</p><img src="https://counter.theconversation.com/content/205979/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>Animal sounds provide an engaging way for children to learn speech and language and can help them develop cognitive skills.Boshra Bahrami, Master's student, Health and Rehabilitation Sciences, Western UniversityBarbara Jane Cunningham, Assistant Professor, School of Communication Sciences and Disorders, Western UniversityZoe A. Leyland, Coordinator, EDIDA and Interprofessional Education, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/907262018-01-31T00:00:28Z2018-01-31T00:00:28Z‘Talking’ killer whale reveals orcas can learn to mimic human speech<figure><img src="https://images.theconversation.com/files/204017/original/file-20180130-107676-ggbyy3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/killer-whale-water-3656209?src=HBPKb1xn8tpMVeHklDriDA-1-51">Shutterstock</a></span></figcaption></figure><p>History will record that in the second decade of the third millennium, a killer whale uttered the word “hello” to a human. After eons of existential wandering in the forest of cosmic loneliness, has humanity finally made contact with another consciousness, not from another world but, astonishingly, the oceans of our own?</p>
<p>Although scientists <a href="http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2017.2171">have reported</a> an <em>Orcinus orca</em> at a marine park in Antibes, France, making noises that sound like human speech, the whale was not talking, any more than <a href="http://sites.bu.edu/guentherlab/miscellaneous-videos-and-oddities/hoover-the-talking-seal/">Hoover the seal</a> or <a href="https://www.theguardian.com/science/video/2012/nov/01/koshik-elephant-talks-korean-video">Koshik the elephant</a> or uncountable parrots were when they produced recognisable copies of human words.</p>
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<p>Nevertheless the study, from researchers led by José Abramson at the Complutense University of Madrid and including my St Andrews colleague Josep Call, is still important. Not because it means whales can speak English, but that they are capable of one of the core building blocks of language development in humans: vocal learning, the ability to copy novel sounds.</p>
<p>The astonishing thing about a whale saying “hello” is not what it means to us, but what it means to them – absolutely nothing. It was specifically chosen, along with some other words, phrases and nonsense sounds, as being something completely outside the normal sound repertoire of the whales. So when the whale produced reasonable copies of the sounds when instructed to, often on the very first attempt, it was pretty conclusive evidence that these animals have the capability to learn new sounds by copying.</p>
<p>Abramson and his colleagues did more than this, as they tested multiple sounds in three situations. In one, the whale was instructed using gestures to produce a sound to copy. In another, the target sound was played back through a loudspeaker. And in a third, a human produced the target sound. Each time, the whale’s responses were subjected to forensic acoustic analysis to measure just how good the copies were. The answer? Pretty darn good.</p>
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<p>The evidence that killer whales can show vocal learning provides us with a missing piece of understanding about their lives in the wild. We’ve long known that killer whales have group specific dialects, collections of distinctive calls that are unique to single pods, or sets of pods. For decades scientists have suggested that <a href="http://www.nrcresearchpress.com/doi/abs/10.1139/z91-206">these dialects are the result of learning</a>, and many clues have supported this view.</p>
<p>We have tracked parallel changes in the calls of wild pods <a href="https://www.sciencedirect.com/science/article/pii/S0003347200914544">over time</a>, we know that captive killer whales moved to different locations have changed their calls to fit in with the other whales <a href="http://jeb.biologists.org/content/217/8/1229">at their new home</a>. The genetic data is <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2012.01872.x/abstract">also consistent with this idea</a>. And we have circumstantial evidence of an individual copying the sound <a href="http://rsbl.royalsocietypublishing.org/content/2/4/509">of another species</a> (a sea-lion). But now we have gold-standard controlled experimental evidence. Now, any explanation of these vocal dialects that doesn’t involve learning looks pretty outlandish.</p>
<p>Killer whales live in a society organised around females. The vocal traditions that these animals learn as they grow up are crucial components of their behaviour. But they are only part of a suite of knowledge and behaviour that they acquire, largely from their mothers, aunts, and grandmothers</p>
<p>My colleague Hal Whitehead and I have argued that <a href="http://press.uchicago.edu/ucp/books/book/chicago/C/bo12789830.html">this cultural inheritance is vital to whales’ lives</a>. Without it, they are incomplete. So it is somewhat ironic that this study, performed on captive animals, adds to a growing picture of the importance of cultural inheritance in their lives and to the case that these animals should never be kept captive. It is impossible for the whales in captivity to develop and express their cultures in anything like the richness we see in the wild.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/204018/original/file-20180130-107690-1j6egy0.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">Whales learn in families.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/killer-whales-orcinus-orca-show-water-733900609?src=HBPKb1xn8tpMVeHklDriDA-1-2">Shutterstock</a></span>
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<p>Of course, killer whales are not alone in their ability to mimic human speech. We’ve known for centuries that some birds can do it, as can a select other few species of mammal including <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2002556">bats</a>, seals, elephants, and other cetaceans such as <a href="http://www.pnas.org/content/110/32/13216.full">bottlenose dolphins</a>. Notably absent on this list are our closest living relatives, the chimpanzees and bonobos. True, chimps can subtly modify an existing call to match <a href="https://www.sciencedirect.com/science/article/pii/S0960982214016352">their group mates</a>, but they have never been shown to be able to copy a completely novel sound.</p>
<p>While vocal learning underpins something only humans do – communicate via spoken language – it is intriguing that our closest primate relatives can’t do it. It tells us something crucial happened in human evolution after our ancestors separated from the other apes some 5m years ago.</p>
<p>We don’t know why this is, but studying the surprising distribution of vocal learning across the animal kingdom is one way to look for clues. Was it, for example, a result of a more mobile lifestyle? Birds, bats, and cetaceans are all highly mobile, but elephants less so. No current answer completely explains all the data, but then our picture is still far from complete.</p>
<p>What’s next for the science of “talking” whales? It is clear that there is a lot of complex communication going on in whale and dolphin societies, much of which we still don’t understand. We are facing a vast ocean of ignorance. To rectify this, in my view, we need to drop our stifling and frankly navel-gazing, human-centric focus on asking “can whales talk?”. Instead, we should learn more about how each cetacean species has ways of communicating that are specific to their environment and how they have evolved. Only then will we be able to appreciate their true wonder.</p><img src="https://counter.theconversation.com/content/90726/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luke Rendell receives funding from the Marine Alliance for Science and Technology for Scotland (MASTS) pooling initiative (Scottish Funding Council HR09011). </span></em></p>An animal behaviour expert gives his view on finding that a killer whale can copy the sound ‘hello’.Luke Rendell, MASTS Lecturer in Biology, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/802162017-07-03T10:45:38Z2017-07-03T10:45:38ZDo cats purr when humans aren’t around?<figure><img src="https://images.theconversation.com/files/176426/original/file-20170630-23414-fufmih.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-kitten-likes-being-stroked-by-507456550?src=TYXiUj_9AxXcJbcbp8sb2Q-1-15">PHOTOCREO Michal Bednarek/Shutterstock</a></span></figcaption></figure><p>Why do cats purr? Humans tend to think that purring is a sign of happiness in a cat – and indeed it can be – but there are other reasons why our feline friends produce this particular vocalisation. </p>
<p>Purring is a habit that develops very early in a cat’s life, while suckling from its mother, so clearly it is not a sound that is directed solely at humans. Cat owners will be well aware that a cat can produce more than one kind of purr, just as they have a whole repertoire of meows, chirps, growls, spits and other sounds.</p>
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<p>The purr that is produced during suckling, is quite different in quality to the purr that you will hear when your cat is sprawling across your lap being stroked. <a href="http://ac.els-cdn.com/S0960982209011683/1-s2.0-S0960982209011683-main.pdf?_tid=ca2feb88-5bde-11e7-a4e7-00000aab0f26&acdnat=1498639989_de63d91cbfcdfca568260fc9abd07b74">Analysis of the sound</a> has shown when a cat is asking for food, whether from its mother or a human – the purr contains a high-pitched note that is similar in frequency to a cry (though not as loud). It may have something of the effect of the cry of a newborn, which affects the hormonal state of female mammals and <a href="http://ac.els-cdn.com/S0166432807000897/1-s2.0-S0166432807000897-main.pdf?_tid=e02955ac-5d08-11e7-b2f7-00000aab0f01&acdnat=1498768017_ddab9098f69493f99acf804e0fd07bc3">elicits a care-giving response</a>.</p>
<p>When a cat is being petted or is snuggled up to its owner on the sofa, the purr it produces is much more soporific and generally soothing, and acoustic analysis shows that <a href="http://ac.els-cdn.com/S0960982209011683/1-s2.0-S0960982209011683-main.pdf?_tid=ca2feb88-5bde-11e7-a4e7-00000aab0f26&acdnat=1498639989_de63d91cbfcdfca568260fc9abd07b74">the “cry” component is missing</a>. </p>
<p>Adult cats will often purr when they are close to or in <a href="http://journals.sagepub.com/doi/full/10.1016/j.jfms.2003.09.013">physical contact</a> with another cat, engaging in grooming for example. They will also do it when they play with an inanimate object, or while eating, which can be at a time when they are alone. However, the most usual time for purring is in company, and it can be the care soliciting sound, asking to be fed or stroked, or an indication of social pleasure. </p>
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<img alt="" src="https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/176421/original/file-20170630-8225-c6s6ug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&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">Cats often purr whilst grooming one another.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/one-cat-grooming-another-105962432?src=RTOsf0lp6aBkWKFLT8JjRg-1-44">karamysh/Shutterstock</a></span>
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<h2>The darker side</h2>
<p>Strangely, vets also report that cats will purr when they are in <a href="https://books.google.co.uk/books?hl=en&lr=&id=GgUwg6gU7n4C&oi=fnd&pg=PA67&dq=purring+in+solitary+felines&ots=V-aN4Ee6c9&sig=UqH6gx1KDoto8wtzJjgn7tS3g8M#v=onepage&q=purring%2520in%2520solitary%2520felines&f=false">great pain</a> or just before death. This seems to be illogical if it is a sound relating to pleasure, but in fact, it could be that the cat is asking for help. </p>
<p>It could also be a way of masking the fact that the cat is injured and vulnerable. If you are a small animal, even a carnivore, it is not good to show weakness as this could encourage larger predators to come along and eat you. The purr may be the cat equivalent of “everything’s fine, I’m on top of the world. Nothing to see here, move along please”.</p>
<h2>Can big cats purr too?</h2>
<p>There has long been a debate about whether the “big cats” can purr – and the belief has been that cats that roar, such as lions and tigers, cannot purr. Although there is no conclusive evidence on this subject, it seems that even cats that roar <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2907.2002.00113.x/full">purr as cubs</a> while suckling. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=482&fit=crop&dpr=1 600w, https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=482&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=482&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=606&fit=crop&dpr=1 754w, https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=606&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/176406/original/file-20170630-8242-n663ao.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=606&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It is suggested that cheetahs may purr too.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/dianasch/15650436564/">Diana Robinson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>All mammals have a bone or series of bones in the throat called the hyoid apparatus, which supports the larynx and tongue. In cat species that roar the <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1469-7580.2002.00088.x/full">hyoid apparatus is not entirely made of bone</a> but retains some parts as cartilage, while cat species that purr have a hyoid that is completely bony. This modification may permit roaring, but does not necessarily mean that purring is impossible. It is believed that cheetah, ocelot, margay, serval, and lynx, among other species, can purr, and it is suggested that <a href="http://www.zobodat.at/pdf/Zeitschrift-Saeugetierkunde_59_0087-0104.pdf">jaguar, leopard, lion and tiger</a> cannot – or if they can they’ve kept it secret all these years.</p>
<h2>Process behind the purr</h2>
<p>The actual process of <a href="http://www.sciencedirect.com/science/article/pii/0034568772900643">producing the purring sound</a> is complicated, and is still not completely understood, but it involves the muscles of the larynx and the diaphragm being activated by bursts of nerve activity that originate in the brain and occur 20 to 30 times every second. This happens on both in and out breaths, which accounts for the continuous sound of the purr. </p>
<p>The fact that a cat can do all this and simultaneously eat, knead the cushions, rip the chair leg to pieces or weave complicated patterns through your legs without getting stepped on makes one wonder what they would have achieved with opposable thumbs.</p><img src="https://counter.theconversation.com/content/80216/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jan Hoole 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>Humans tend to associate cats purring with happiness, but in turns out they also purr when in pain, hungry and alone.Jan Hoole, Lecturer in Biology, Keele UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/699142016-12-11T06:18:04Z2016-12-11T06:18:04ZHow we learned to listen to elusive, threatened frogs<figure><img src="https://images.theconversation.com/files/148908/original/image-20161206-25738-16zp2hx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Cape peninsula moss frog is smaller than 20mm and is, therefore, hard to monitor.</span> <span class="attribution"><span class="source">Francois Becker</span></span></figcaption></figure><p>Scientists the world over have a frog problem: we have little idea of how many frogs there are in each species in the world. This means that we are unable to predict how many there will be in the future due, for example, to the effects of climate change.</p>
<p>There have been very few studies recording the size of amphibian populations. So those of us studying amphibians have very little with which to work. What we do know is that many frogs are under threat mostly from habitat change, but also from disease. In southern Africa they are particularly vulnerable to <a href="http://john.measey.com/media/545057e1-8025-4abd-9aa7-3a90f470dd01/NgmUbw/PDFs/Measey_2011_Ensuring.pdf">invasive species</a>.</p>
<p>Male frogs advertise their presence with species specific mating calls. Determining their presence has traditionally entailed listening for these calls. If you want to know how many frogs are calling, then stand with your hands behind your ears and try to count all the animals you hear. It sounds simple, but it’s not that easy. I’ve tried. </p>
<p>Listening to 10 calling animals is taxing. More than 10 and it’s possible to get muddled. Choruses of over 50 sound like noise. </p>
<p>Luckily the revolution in digital media has helped those of us studying amphibians. We’re able to monitor vocalising species and record a large number of sounds from the environment. Automated computer software, like voice recognition on smart phones, can then pick out particular species from their calls. Acoustic monitoring is ideal for monitoring the abundance of a species over time, as it has minimal impact on the species being monitored. </p>
<p>But what then? Interpreting the number of calls is problematic for several reasons. First and foremost is the fact that the area a microphone listens to is not defined. The vagaries of the acoustic environment mean that the slightest wind, or even a change in humidity, can affect the distance over which sound propagates. This means that microphones listen to different areas every time they record.</p>
<p>Recently <a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12810/full">published research</a> by my colleagues and I could change this. It provides a methodology for acoustic monitoring that calculates the area listened to by an array of microphones, as well as estimating the number of calls made in that area. This has important implications for acoustic monitoring – and for attempts to catalogue just how many frogs are “ribbiting” around us. </p>
<h2>A new methodology</h2>
<p>We used microphones to monitor the Cape peninsula moss frog (<em>Arthroleptella lightfooti</em>) in Table Mountain National Park, South Africa. These frogs are endemic to the area and occur nowhere else on the planet. They are listed as “<a href="http://www.iucnredlist.org/details/58061/0">Near Threatened</a>” on the IUCN list of threatened species. Any data we can glean will contribute to their conservation. </p>
<p>We used an array of six microphones to monitor populations of Cape peninsula moss frogs over their winter breeding season from May to October. </p>
<p>Researchers have previously used time of arrival of sound at each microphone in an array to determine the position <a href="https://youtu.be/JTYFYtZJXro">of calling animals</a>. </p>
<p>We used a novel statistical technique developed by co-author statisticians Stevenson and Borchers (<a href="http://john.measey.com/ascr">Spatial Capture Recapture: SCR</a>) to analyse the automated call data. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/148901/original/image-20161206-25721-ysekwe.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>
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<span class="caption">Listening for calls of the endangered Arthroleptella subvoce to monitor its abundance in the Groot Winterhoek Wilderness Area, South Africa.</span>
<span class="attribution"><span class="source">John Measey</span></span>
</figcaption>
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<p>The analysis takes into account both microphones which hear calls and those which don’t hear calls, as well as the distance between microphones to build up an estimate of the number of calls and the <a href="https://youtu.be/JTYFYtZJXro">area from which the calls come</a>. For an encore, the statisticians combined the information from time of arrival and call amplitude difference with Spatial Capture Recapture to build the first ever statistical estimate of the density of calling male frogs from an acoustic array.</p>
<p>We also recorded rainfall and temperature and were surprised to find that the number of frogs calling at each site didn’t relate to either of these factors. Instead, it started off with relatively few animals calling early in the season (May), built to a fine crescendo in July and then tailed off toward October.</p>
<p>More surprising was that the area in which the microphone array could detect frog calls nearly doubled (from 400 to 800 m₂) during the winter breeding season. But because the technique accounted for this change in the size of the sampling area we could effectively monitor the calling density of the species without having to worry about the changing areas that the microphones recorded.</p>
<h2>The new direction</h2>
<p>The idea of using an array of microphones is not new. Using the time of arrival of sounds to each microphone to determine the presence of a calling animal, such as a frog, is old hat. The technique we’ve <a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12810/full">pioneered</a> provides a new direction for acoustic monitoring because we were able to define the area in which the microphone array was detecting calls. </p>
<p>The study has produced a robust technique for estimating call density. This is because it combined the statistical wizardry that allowed estimates from Spatial Capture Recapture with the time of arrival and signal strength. That combination makes it possible to increase the accuracy of the estimate of call density.</p>
<p>Researchers wishing to take advantage of the wonders of digital media to monitor species at risk of climate change, <a href="https://theconversation.com/the-future-for-frogs-looks-bleak-unless-humans-change-their-habits-57505">like frogs</a>, can now use a technique that will give them call density which can be compared across recording occasions. </p>
<p>This will contribute to our understanding of how threatened species which vocalise are faring on our changing planet.</p><img src="https://counter.theconversation.com/content/69914/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Measey receives funding from National Geographic, the Centre for Invasion Biology (CIB), and the National Research Foundation (NRF). </span></em></p>A robust technique using the wonders of digital media has helped researchers understand how threatened species like frogs are faring on our globally changing planet.John Measey, Senior Researcher at the CIB based in the Department of Botany and Zoology, Stellenbosch UniversityLicensed as Creative Commons – attribution, no derivatives.