tag:theconversation.com,2011:/global/topics/crows-3492/articlesCrows – The Conversation2023-09-14T08:22:49Ztag:theconversation.com,2011:article/2129142023-09-14T08:22:49Z2023-09-14T08:22:49ZAre crows really that clever?<p>It’s no secret corvids are endowed with remarkable cognitive abilities.</p>
<p>Internet is awash <a href="https://www.youtube.com/watch?v=PZXmV0BfCWs">with videos of crows</a> imitating voices or solving complex brainteasers. But are these birds as intelligent as they are made out to be?</p>
<h2>The nutcracker puzzle</h2>
<p>One of the most quoted studies to back up the thesis of a superior intelligence in corvids is that of crows using cars as nutcrackers. In 1978, <a href="https://academic.oup.com/auk/article-abstract/95/4/760/5208772">researchers in California</a> noted that American crows would throw nuts on the road, wait for a car to crush them and then feast on the shattered fruit.</p>
<p>Despite being widely circulated by the media and even by other scientists, the study is a textbook example of how studying animal behaviour can lead us, often unintentionally, to anthropomorphise – i.e., assign animals abilities or thoughts similar to humans’, when their behaviour is actually explained by different processes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341665/original/file-20200614-153817-8rc66s.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">American crow calling.</span>
<span class="attribution"><a class="source" href="https://fr.wikipedia.org/wiki/Corneille_d%27Am%C3%A9rique#/media/Fichier:Corvus_brachyrhynchos_30157.JPG">Walter Siegmund/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In 1997, <a href="https://sora.unm.edu/sites/default/files/journals/auk/v114n02/p0296-p0298.pdf">researchers at the University of California</a> took a closer look at the crows’ behaviour to check whether they did indeed use cars as nutcrackers. They hypothesised that if crows really understood that cars could pry nuts open, then the animals would place their nuts on the road and not remove them when a car approached.</p>
<p>However, the academics found that the crows did not throw their nuts onto the road when a car was approaching any more than when the road was empty. What’s more, out of the 200 cases studied, the researchers never saw a car crush a nut. This showed that the theory that crows were consciously using cars as nutcrackers was in fact false: crows drop their nuts on hard surfaces to crack them (such as roads) and a car sometimes crushes one. This is a happy coincidence for the crow, which does not, however, make the connection between the car and its meal.</p>
<h2>Proven cognitive abilities</h2>
<p>More recent research that was carried out with methods specifically designed to limit anthropomorphism is restoring corvids’ reputation for smarts. For example, it was long thought that only primates knew how to use tools. But since the 2000s, a host of studies has shown that several other species are capable of reproducing this feat, including <a href="https://www.pnas.org/content/102/25/8939.short">dolphins</a>, <a href="https://www.sciencedirect.com/science/article/pii/S0960982209019149">octopuses</a>, <a href="https://www.pourlascience.fr/sd/ethologie/lintelligence-des-grands-corbeaux-comparable-a-celles-des-grands-singes-et-des-enfants-12661.php">corvids</a> (crows included) and even <a href="https://www.sciencedirect.com/science/article/abs/pii/S1616504719300333?via%3Dihub">pigs</a>.</p>
<p>Corvids also appear to be highly sophisticated tool wielders thanks to their ability to <a href="https://psycnet.apa.org/record/2008-07027-001">choose and even manufacture tools of the right length and diameter</a> for the task they want to accomplish, such as twigs. For example, New Caledonian Crows have a track record of <a href="https://www.nature.com/articles/379249A0">producing hooks</a> by bending materials.</p>
<p>They also have an impressive memory for faces. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0003347209005806">Researchers at the University of Washington, Seattle, tested this ability by donning a mask</a> to capture and then release American crows. Wild birds <a href="https://www.youtube.com/watch?v=bOkj7lJpeoc">would go on to aggressively scream every time they saw the masks</a>, more than two years after they were caught. Even crows that had not been captured learned to recognise and avoid this threatening figure by <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2011.0957">observing the behaviour of their companions</a>. This study is the first to show that wild, non-domesticated animals can recognise a human by their face and can remember it for several years, passing on this information to their fellow animals. The extent of this recognition is quite remarkable, both in temporal and social terms.</p>
<h2>Master Raven and self-control</h2>
<p>In <a href="https://link.springer.com/article/10.1007/s10071-019-01317-7">another experiment</a>, Rachael Miller and her colleagues at the University of Cambridge compared the self-control of Caledonian crows with that of children aged 3 to 5. Self-control is what enables us, for example, to reason with ourselves when we want to watch the last episode of a series so as not to be tired the next day. It’s an aspect of executive control, which enables us to make good decisions and plan for the future. Adults are generally able to use self-control without too much difficulty, but children only start to develop this ability between the ages of 3 and 5.</p>
<p>The experiment tested a specific aspect of self-control: delayed gratification, which occurs when you have to choose between a mediocre but immediate reward and a much better reward that is not immediately available. A typical example of delayed gratification is <a href="https://www.youtube.com/watch?v=QX_oy9614HQ">the marshmallow experiment</a>.</p>
<p>In Miller’s experiment, children and crows were presented with a slowly spinning tray containing two rewards (different stickers for the children, and sweets for the crows): one of the two rewards was more interesting to the subject, either because it was bigger or because it was of better quality. As it rotated, the tray made the less valuable reward accessible to the subjects, who could then grab it. If they succumbed, the tray then stopped spinning. However, if they waited for the first reward to pass, then the second, much more interesting one, became accessible to them.</p>
<p>The experiment included two tests: one in which the two rewards were visible all the time, and another where they only came into view when the tray started to spin. In the second trickier test, the second most coveted reward was not visible while the first passed in front of the subjects, who then had to use their memory on top of self-control. In the first test, both the crows and the children were able to wait for the best reward. But in the second one, the children outperformed the crows, because the latter were unable to wait for a reward they could no longer see.</p>
<p>In fact, this experiment is one of the few that has attempted to directly compare animals and children in terms of cognitive ability, using the same task for both species. Such results are therefore very interesting and give us a better perspective on the intelligence of crows.</p>
<p>However, we must bear in mind that animals are often tested on abilities that we, as humans, find important and in which we excel. Our biased view of the abilities of other species leads us to believe that we are the most intelligent creatures on Earth. But if crows were to test us in areas where they are highly intelligent, such as visual memory, navigation in 3D space or perception of the Earth’s magnetic field, would we be able to compete?</p><img src="https://counter.theconversation.com/content/212914/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mélissa Berthet a reçu des financements du Fond National Suisse et de l'Université de Zürich. </span></em></p><p class="fine-print"><em><span>Sonya Kaiser ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Scientists pour over the existing literature on corvids’ smarts to debunk some myths, and uphold others.Mélissa Berthet, Docteur en biologie spécialisée en comportement animal, University of ZurichSonya Kaiser, Dual Masters in Brain and Mind Sciences, Sorbonne UniversitéLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1998672023-02-17T03:38:25Z2023-02-17T03:38:25ZDead kangaroos make a surprising feast for possums in the Australian Alps<figure><img src="https://images.theconversation.com/files/510757/original/file-20230217-28-n3s0iu.JPG?ixlib=rb-1.1.0&rect=33%2C52%2C2002%2C1394&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Brushtail possums were caught on camera eating the flesh of a dead kangaroo.</span> <span class="attribution"><span class="source">James Vandersteen/University of Sydney</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Vultures, hyenas, and Tasmanian devils are highly efficient scavengers, able to locate and consume carrion rapidly, including the meat and bones. </p>
<p>When we think of scavengers, these large carnivores are what comes to mind – not brushtail possums.</p>
<p>So it came as a surprise when these Australian marsupials turned out to be one of the most common scavengers we caught on camera in our <a href="https://www.publish.csiro.au/wr/Fulltext/WR22100">new study published online this month in Wildlife Research</a>. </p>
<h2>Circle of life</h2>
<p>No vertebrate Australian animals survive exclusively by scavenging – for our wildlife, carcasses are a “<a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ddi.13390">sometimes food</a>”.</p>
<p>Scavengers play an important role as ecosystem cleaners, helping to remove carcasses from our landscapes by eating them.</p>
<p>With this in mind, we wanted to know how different seasons affect the use of carcasses by vertebrate scavengers in Kosciuszko National Park, south-east NSW, in the Australian Alps. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="panorama from a mountaintop of other snow-capped, wide mountain ranges below a cloudy sky" src="https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=235&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=235&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=235&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=296&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=296&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510756/original/file-20230217-14-gm9qj0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=296&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mount Howitt, Victoria, is a part of the Australian Alps and experiences a wide range of temperatures.</span>
<span class="attribution"><span class="source">Loco Photography/Shutterstock</span></span>
</figcaption>
</figure>
<p>Winter in the Australian Alps covers much of the landscape in snow. But by the following summer, that same landscape can warm up considerably and even experience intense <a href="https://bioone.org/journals/Mountain-Research-and-Development/volume-23/issue-3/0276-4741(2003)023%5B0294:ABROTA%5D2.0.CO;2/A-Brief-Report-on-the-2003-Australian-Alps-Bushfires/10.1659/0276-4741(2003)023%5B0294:ABROTA%5D2.0.CO;2.full">bushfires</a>. </p>
<p>We found scavenging was highly seasonal in terms of who visits carcasses throughout the course of a year. Most surprisingly, brushtail possums and ravens drove these seasonal trends, as the most common scavengers recorded, with possums mostly scavenging in winter, and ravens in spring. </p>
<p>These findings emphasised the key role of smaller scavenger species, and uncovered novel insights into the feeding habits of the brushtail possum, which is generally considered to eat mostly plants and insects. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/DS4EDaoZy18?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>Catching possums in the act</h2>
<p>We expected to see different scavengers appearing with each season, so our monitoring ran across the course of a full year from March 2020 till March 2021. </p>
<p>Each consecutive season (starting in autumn, then winter, spring, and summer) we placed 15 fresh eastern grey kangaroo carcasses – sourced from local culls – throughout the alpine environment (60 carcasses total). </p>
<p>Each of these carcasses were monitored by a remote camera for 60 days to record every species that visited, whether that be to investigate or feed on the carcass. </p>
<p>Across 745,599 remote camera images, the scavenger species we recorded were spotted-tail quolls, feral cats, dingoes, pied currawongs, wedge-tailed eagles, brushtail possums, ravens, red foxes, and feral pigs. </p>
<p>Of the scavenging we recorded, 88% was done by brushtail possums and ravens. </p>
<figure class="align-center ">
<img alt="A 3 by 3 grid of photos of animals taken by remote capture. In each photo, the animal is visiting/scavenging on kangaroo carcass." src="https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510765/original/file-20230217-18-ugmd4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our remote camera captured a range of scavengers in the Australian Alps: a) spotted-tail quoll, b) feral cat, c) dingo, d) pied currawong, e) wedge-tailed eagle, f) brushtail possum, g) raven species, h) red fox and i) feral pig.</span>
<span class="attribution"><span class="source">James Vandersteen/University of Sydney</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Surviving the seasons</h2>
<p>We expected the time it would take the scavengers to find – and subsequently scavenge – a carcass would be linked to the smelliness of the carcass. </p>
<p>During summer, we thought, that heat would make the carcasses’ odours more pungent, and therefore easier to find. </p>
<p>We were wrong about that, not in terms of the smell, but how quickly vertebrate scavengers would find the carcasses. </p>
<p>It actually took vertebrate scavengers longer to find the carcasses in the summer, whether for investigation or scavenging. In the winter, carcass visits peaked.</p>
<p>But, we have a potential explanation for this. </p>
<p>In the summer, a carcass is colonised by many scavenging insects within minutes of its death. These “mini scavengers” may have sped up carcass decomposition so much, that vertebrate scavengers had little time to find the fresh carcasses. </p>
<p>Scavenging rates might also have been lowest in the summer because other food sources were abundant.</p>
<p>Brushtail possums, for instance, eat mostly leaves, flowers, fruit and insects, most of which are only seasonally available during summer. </p>
<p>In the winter, when these food sources are scarce, brushtail possums accounted for 81% of all recorded scavenging. They were eating carrion three times more often than during summer. </p>
<figure class="align-center ">
<img alt="A brushtail possum in the snow at night, rearing up next to a kangaroo carcass" src="https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510775/original/file-20230217-14-kwzkku.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A brushtail possum braving the cold to ‘protect’ its kangaroo carcass.</span>
<span class="attribution"><span class="source">James Vandersteen/University of Sydney</span></span>
</figcaption>
</figure>
<h2>Feeding the family</h2>
<p>We also considered that the scavengers’ breeding seasons might have an impact on their scavenging rates and behaviours. </p>
<p><a href="https://www.publish.csiro.au/WR/WR15039">Ravens breed</a> from late winter into early spring, and initially prioritise nest construction.</p>
<p>This was even captured by our remote cameras, where ravens were observed collecting fur from the kangaroo carcasses, presumably for nest construction. </p>
<figure class="align-center ">
<img alt="Ravens stand around a kangaroo carcass in the snow, with tufts of kangaroo fur in their beaks" src="https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510769/original/file-20230217-18-2z5hy5.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This breeding pair of ravens decided that kangaroo fur would make comfy nesting material.</span>
<span class="attribution"><span class="source">James Vandersteen/University of Sydney</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Following nest construction, chick rearing often requires breeding pairs to divide time between foraging, feeding chicks, and protecting the nest. </p>
<p>Inherently, during this time, ravens require more energy and must supplement their diets with lots of high-energy food, <a href="https://www.researchgate.net/publication/241692417_The_scavenging_behaviour_of_the_Australian_Raven_Corvus_coronoides_Patterns_and_influencing_factors">such as carrion</a>.</p>
<p>Of all the raven scavenging we recorded, 67% was done during spring. This suggests ravens rely heavily on carrion to supplement their own diet – and that of their chicks – during their breeding season. </p>
<figure>
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</figure>
<h2>Where were the usual suspects?</h2>
<p>It was also clear that the larger species (dingoes, wedge-tail eagles, feral pigs) were scarcely recorded at the carcass sites. Low rates of scavenging by these larger animals could be another reason why the smaller scavengers were so common.</p>
<p>This is because larger scavengers can scare away or predate on smaller scavengers, potentially moving them away from carcasses. Larger scavengers also have bigger appetites, so in their absence, there was potentially more carrion for smaller species to find.</p>
<p>Although we do not have a good estimate of the true density of larger scavengers in the surrounding environment, species like the dingo are subject to control in the broader region, potentially limiting their numbers. </p>
<figure class="align-center ">
<img alt="A brindle coat dingo stands in an Australian alpine bushland in front of a kangaroo carcass, looking at the camera, licking its lips." src="https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510760/original/file-20230217-964-xwkv53.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">We expected to see dingos scavenging. This one seems to have noticed the camera.</span>
<span class="attribution"><span class="source">James Vandersteen/University of Sydney</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Beyond the mountains</h2>
<p>Given the extent of culling operations in Australia targeting overabundant native species (like kangaroos) or pests such as deer and horses, not to mention all the road-kill, it is important to understand what is happening to carcasses in the landscape. </p>
<p>Our study has set a baseline for scavenging dynamics in an alpine ecosystem, and our methods could be used to learn more about the ecology of scavenging in many different environments. </p>
<p>In this case, it was (surprisingly) brushtail possums who appear to be taking advantage of carcasses as a source of food in the Australian Alps.</p><img src="https://counter.theconversation.com/content/199867/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work was funded by the Australian Alps National Parks Cooperative Management Program.
James Vandersteen undertook this work as an MPhil student at The University of Sydney. He is, however, currently affiliated with The University of New South Wales as a PhD student.</span></em></p><p class="fine-print"><em><span>This work was funded by the Australian Alps National Parks Co-operative Management Program. Funding/support for related work in the study region has been received from the Australian Pacific Science Foundation, Hermon Slade Foundation, Australian Government, NSW Government (South East Local Land Services, NSW National Parks/NSW Environment Trust), and Australian Geographic. Thomas Newsome is a Council member of the Royal Zoological Society of New South Wales, a member of the Australian Mammal Society and Ecological Society of Australia, and President of the Australasian Wildlife Management Society. </span></em></p>When they set up remote cameras throughout the bush, scientists were not expecting to capture these small marsupials scavenging for flesh.James Vandersteen, PhD Student, UNSW SydneyThomas Newsome, Senior lecturer, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/806272017-07-13T18:23:51Z2017-07-13T18:23:51ZClever crows can plan for the future like humans do<figure><img src="https://images.theconversation.com/files/178057/original/file-20170713-12477-1vs2jey.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">from www.shutterstock.com</span></span></figcaption></figure><p>Humans aren’t as unique as we used to think. Not, at least when it comes to making plans for the future. Scientists originally thought humans were the only animals that made plans but, over the past decade, studies on non-human primates and the crow family have challenged this perspective.</p>
<p>For example, we’ve seen that these animals are able to <a href="http://science.sciencemag.org/content/312/5776/1038">store tools for later use</a>, cache food in places where it will be <a href="https://www.nature.com/nature/journal/v445/n7130/abs/nature05575.html">needed the most</a>, and hide pieces of the sort of food they know will be running low <a href="https://www.nature.com/nrn/journal/v4/n8/abs/nrn1180.html">in the future</a>.</p>
<p>In all these studies, the animals had to consider what to do, where to do it and when to prepare for certain specific future events. <a href="http://science.sciencemag.org/cgi/doi/10.1126/science.aam8138">The latest research</a> shows that ravens can indeed anticipate the “what, where and when” of a future event on the basis of previous experiences. But unlike the previous studies, this work tested the birds in behaviour they don’t normally show in the wild. This provides evidence that they have a much more general ability to plan for the future than previously thought.</p>
<p>Food hoarding is common in members of the crow family (corvids) because they often eat from perishable animal carcasses, which provide lots of food but are only available for a <a href="http://rstb.royalsocietypublishing.org/content/365/1542/977.short">short amount of time</a>. To create a suitable cache of food they need to work out what to store, where to put it and when to do so.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178058/original/file-20170713-12477-1xk4l5b.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"></span>
<span class="attribution"><span class="source">from www.shutterstock.com</span></span>
</figcaption>
</figure>
<p>The new study, published <a href="http://science.sciencemag.org/cgi/doi/10.1126/science.aam8138">in the journal Science</a>, tested the birds outside this naturally occurring behaviour, which may have evolved specifically because it gives crows a survival advantage. Some crow species are known to naturally <a href="http://www.sciencedirect.com/science/article/pii/S0960982205000801">use tools to retrieve food</a>. So the researchers tested whether the birds could store and retrieve a tool so they could get at their food after a gap of 17 hours – something we wouldn’t expect them to do naturally. The scientists didn’t give the birds a chance to learn this behaviour first but they were still able to instantly select the tool out of a number of unnecessary items.</p>
<p>In another experiment, the researchers taught ravens to select a token from a number of items that they could then exchange for food. Again, the birds then showed that they could plan for the future using this new behaviour. They were able to store this token and then retrieve and use it when they were offered the chance to exchange it for food 17 hours later.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EZSk7oCNaHg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>This contrasts with all of the previous studies in future planning, which have focused on naturally occurring behaviour. For example, we know that California scrub jays <a href="https://www.nature.com/nature/journal/v445/n7130/abs/nature05575.html">cache their food</a> according to their future needs. And that bonobos, chimpanzees and orangutans select, transport and <a href="https://link.springer.com/article/10.1007/s10071-008-0157-0">save appropriate tools</a> for future needs.</p>
<h2>General intelligence</h2>
<p>These studies have shown that animals can plan for the future – but they left an important question open for debate. Are animals only able to plan to use abilities that have evolved to give them a specific advantage, or can they flexibly and intelligently apply planning behaviour across various actions? Most critics <a href="http://psycnet.apa.org/index.cfm?fa=search.displayRecord&uid=1997-06446-001">would say the former</a>, as the animals were tested in naturally occurring behaviours. </p>
<p>But the new research provides the first compelling evidence that animal species can plan for the future using behaviour that doesn’t typically occur in nature. This supports the view that at least some cognitive abilities in animals don’t evolve just in response to specific problems. Instead, it suggests that animals can apply these behaviours flexibly across problems in a similar way to humans.</p>
<p>It seems that, in corvids and apes, intelligence is not a system to solve a predefined set of problems (dedicated intelligence) but rather a computational system to improvise new solutions (improvisational intelligence). But it is still unclear what this cognitive system exactly is and <a href="http://psycnet.apa.org/journals/rev/111/2/512/">how it evolved</a>.</p>
<p>What’s needed now is neuro-biological evidence of general intelligence in animals. We also need to investigate how flexible and improvisational behaviour evolved. Then we might be able to see how crows’ ability to plan for the future fits in with their broader cognitive powers.</p><img src="https://counter.theconversation.com/content/80627/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>New research provides early evidence of general intelligence in animals.Markus Boeckle, Postdoctoral research associate, University of CambridgeNicky Clayton, Professor in Comparative Cognition, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/731522017-02-21T14:46:26Z2017-02-21T14:46:26ZAnimals know when they are being treated unfairly (and they don’t like it)<figure><img src="https://images.theconversation.com/files/157697/original/image-20170221-18627-wc2aiz.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">Claudia Wascher</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Humans beings appear to be <a href="https://academic.oup.com/qje/article/114/3/817/1848113/A-Theory-of-Fairness-Competition-and-Cooperation">hardwired to have a sense of fairness</a>. This is puzzling from an evolutionary perspective, which you would have thought would mean we were predisposed to seek advantage for ourselves and our families wherever possible. But in fact a sense of fairness is important for humans to be able to help each other. Human cooperation is based on reciprocal altruism – we help people because they’ve either helped us in the past or they may help us in the future. </p>
<p>This form of cooperation is only possible when individuals are able to keep track of other individuals’ efforts and payoffs – and a sense of fairness helps with this. But what about non-human animals? Is sense of fairness unique in differentiating humans from other animals or has it evolved in other non-human animals too?</p>
<p>There’s a way of testing for this in animals using an “<a href="http://journal.frontiersin.org/article/10.3389/fpsyg.2017.00270/full">inequity aversion task</a>”. One test subject receives a reward for completing a task, while an experimental partner gets a “booby prize” – something they don’t particularly like. You’d imagine that individual animals that have a strong sense of fair play would either stop taking part in the experiment or refuse the treat.</p>
<p>One of the first species that was tested for inequity aversion were <a href="http://www.sciencedirect.com/science/article/pii/S0003347215000767">brown capuchin monkeys</a>. In a task where the monkeys had to exchange a token for a treat, one individual was given a piece of cucumber in exchange for a token, whereas a model individual – another monkey not the focus of the experiment – in an adjacent cage got a grape for the same action. Capuchin monkeys prefer grapes to cucumbers – and the individual receiving the cucumber soon started to “protest” by throwing the unloved vegetable back at the experimenter. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157674/original/image-20170221-18630-1d2swgu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Capuchin monkeys also showed an awareness of what’s fair.</span>
<span class="attribution"><span class="source">orangecrush, Shutterstock</span></span>
</figcaption>
</figure>
<p>The capuchin monkeys were also well aware of unfairness in the amount of effort they had to expend to receive a reward. When they had to “work” for a reward – and could see that their experimental partner received the reward as a “gift”, they stopped participating. </p>
<p>A number of other primate species, including <a href="http://link.springer.com/article/10.1007%2Fs10071-014-0765-9">chimpanzees</a>, <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153799#">rhesus macaques</a> and <a href="http://onlinelibrary.wiley.com/doi/10.1002/ajp.21014/abstract;jsessionid=8DB6E658D6026F091E6DEBC751314062.f04t02">long-tailed macaques</a>, have been shown to express some form of behavioural responses to inequity. Apart from primates, two further highly social mammalian species, <a href="http://www.sciencedirect.com/science/article/pii/S0168159109001865">dogs</a> and <a href="http://www.psychologie.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Psychologie/CompPsy/Papers/Oberliessen_et_al_2016.pdf">rats</a>, have also been shown to be sensitive to unfairness. </p>
<h2>Bird brains</h2>
<p>But what about non mammalian species? In recent years, the family of corvids has become one of the prime models when it comes to studying cognition in birds. Corvids are a large family of more than 120 species – including ravens, crows, magpies and jays. Corvids are <a href="http://www.sciencedirect.com/science/article/pii/S0960982207014947">highly social and have flexible social systems</a>. Adult ravens for example live in territorial pairs, whereas jackdaws live in large community groups. In some species, such as the carrion crow, sociability depends on the environment – they might breed in male-female pairs in some environments as well as cooperative groups in others. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157698/original/image-20170221-18654-el8v0v.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">Er… excuse me?</span>
<span class="attribution"><span class="source">Claudia Wascher</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Various forms of naturally occurring cooperation can be observed in different corvid species. They help each other in aggressive encounters and share resources such as food or information about predators. So, given the extent to which corvids have been seen to cooperate in the wild, we expected them to have a sense of fairness and unfairness. </p>
<p>We decided to put them to the <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0056885">same test as the primates</a>. The test subjects were four common ravens and six carrion crows. The birds received a piece of cheese as their reward (they like cheese) and a piece of grape as the booby prize. In one experiment, both individuals received the same food reward for exchanging a token with a human experimenter, while in another, one bird received only grapes for exchanging, whereas the other was given cheese. We also tried what’s called an “effort control” experiment in which the test subject had to exchange its token either for a piece of cheese or a piece of grape while the other bird was given the same reward, but got it as a gift and did not have to exchange for it. </p>
<p>In the “inequity” condition the subject crow – the bird that was being unfairly treated – stopped taking the lesser reward. In the “effort control” they stopped exchanging their token for the reward when they saw the other bird getting its reward for no effort. In both cases they could see how they were being treated unfairly and decided not to cooperate.</p>
<p>So in this respect, corvids are like some mammals – and a high complexity and flexibility in cooperation may have driven the evolution of this awareness of what is fair and what isn’t. The fact that inequity aversion is present not only in a number of primate species but also corvids suggests that this idea of fairness and cooperation is something that cooperative species have got in common which has enabled them to evolve sociability.</p>
<hr>
<p><em>Claudia Wascher will be giving a talk: Unfairness ruffles crows’ feathers as part of the <a href="http://www.sciencefestival.cam.ac.uk/">Cambridge Science Festival</a> from March 13 to 26.</em></p><img src="https://counter.theconversation.com/content/73152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Claudia Wascher received funding from 'L'oreal women in science' scholarship. </span></em></p>Like humans, some animals have evolved a highly developed sense of fairness.Claudia Wascher, Lecturer in Animal and Environmental Biology, Anglia Ruskin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/591262016-06-02T09:15:19Z2016-06-02T09:15:19ZThe ‘Houdini’ honey badger … and other surprisingly clever animals<figure><img src="https://images.theconversation.com/files/121750/original/image-20160509-20612-pzis43.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Honey badger: brighter than it looks.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/dl2_lim.mhtml?src=yoSB5mXxLzha1j_lGeTZ_w-1-0&clicksrc=download_btn_inline&id=139560458&size=huge_jpg&submit_jpg=">Shutterstock</a></span></figcaption></figure><p>“What’s that, Lassie? Timmy has fallen down the well?” Lassie was the clever dog that always used to save the day, but stories of clever pets such as <a href="http://www.bbc.co.uk/programmes/p00p0126">skateboarding dogs</a> are well known. It is also widely acknowledged that animals such as monkeys, apes, whales and dolphins are extremely intelligent, but how do we actually define “clever”?</p>
<p>Clever can mean anything from a camouflaged chameleon to an ape using <a href="http://www.bbc.co.uk/programmes/p00p011g">sign language</a> or even employing “<a href="https://theconversation.com/mysterious-chimpanzee-behaviour-may-be-evidence-of-sacred-rituals-55512">sacred rituals</a>”, but clever usually refers to a behaviour rather than a physical appearance. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=836&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=836&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=836&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1050&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1050&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124940/original/image-20160602-23285-1l6dolf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1050&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Just ring the bell…</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>So, how do clever behaviours arise? Conditioning is a learning process whereby an organism undertakes a behaviour in response to a stimulus. <a href="https://web.mst.edu/%7Epsyworld/classical_conditioning.htm">Classical conditioning</a>, such as that expressed by <a href="http://www.simplypsychology.org/pavlov.html">Pavlov’s dogs</a>, is where a neutral stimulus (in this case a bell) is presented with a potent stimulus (food) to stimulate a reflex reaction (salivation). Over time, the neutral stimulus alone stimulates the reaction, thus Pavlov’s dogs eventually salivated whenever they heard the bell ring, whether food followed or not. Indeed, my friend inadvertently conditioned her dog to salivate when he heard the closing Neighbours theme tune – great when she watched it at dinner time, but not so good when she tuned into a rogue episode in the middle of the day.</p>
<h2>Trial and error</h2>
<p><a href="http://www.simplypsychology.org/operant-conditioning.html">Operant conditioning</a>, meanwhile, is where a behaviour is modified by its consequences, and animals learn through trial and error. Imagine some hungry chimpanzees trying to poke termites out of their mound. If one chimp happens to be holding a twig while poking around, it might be small enough to fit into the mound and get covered in termites. If the chimp then pulls the twig out of the mound and eats the termites it has a competitive advantage over the other chimps as it is no longer hungry. If the chimp then learns to associate the implementation of the twig with the increased foraging ability, operant conditioning has occurred. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124939/original/image-20160602-23270-93c91b.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">Octopus: eager to put its operant conditioning to good use.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&search_tracking_id=aJqIm-ZfEZtVPeMA-SgozA&searchterm=octopus%20&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=291282713">Shutterstock</a></span>
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<p>Both classical and operant conditioning are commonly used to train organisms, but it is operant conditioning, the trial and error learning, that typically occurs in the wild. <a href="http://evolution.berkeley.edu/evolibrary/article/evo_25">Natural selection</a> (the survival of the fittest) is where only those that display optimal behaviours will survive long enough to reproduce and pass on their genes (and hence their cleverness). So, the occurrence of clever behaviours, such as tool use, is a combination of trial and error, and evolution.</p>
<p>Humans like to think of themselves as the most intelligent organisms on the planet, so we are always surprised when animals appear clever and often outwit us. But beyond the usual roll call of apes and dolphins, here are some more that are surprisingly clever…</p>
<h2>Super squirrels</h2>
<p>Most animals will do anything for food – for them it is simply a case of eat or die. So it is no surprise that they have learned ingenious ways to access food, such as the squirrels completing the assault course that featured in the Carling Black Label adverts.</p>
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<p>In fact, squirrels, who hide many nuts each autumn, and thus have evolved a high memory capacity to relocate them, have more recently been found to be able to solve complex puzzles whereby they learned that if a hollow contained a reward, <a href="http://www.dailymail.co.uk/sciencetech/article-3151182/Is-grey-squirrels-common-Hidden-hazelnut-puzzle-reveals-intelligence-adaptability-crafty-rodents.html">another reward would be located in the hollow diagonally opposite</a>. Clever stuff.</p>
<h2>Bright birds</h2>
<p>Some species of heron are known for their clever foraging behaviours – they use bait, such as a leaf or piece of bread placed several times on the surface of a water body, to attract fish (akin to a fisherman casting off many times). And once the fish investigate, the <a href="https://www.youtube.com/watch?v=Porp5v5lLKk">heron take aim</a>.</p>
<p>Crows are known to use reasoning to solve problems, but recently they have been taught to exchange collected coins for food in a “<a href="http://www.josh.is/crow-machine/">vending machine</a>”. Although the Crow Machine project is aimed at investigating training in crows, it is thought that it could lead to the learning of other tasks in crows such as collecting rubbish or even search and rescue. Either way, there are some surprisingly bright birds.</p>
<h2>Intelligent invertebrates</h2>
<p>The <a href="https://theconversation.com/octopuses-are-super-smart-but-are-they-conscious-57846">octopus is perhaps the most intelligent of the invertebrates</a>, known to recognise many shapes and patterns. It has also been found to learn through observation rather than just trial and error. For example, when a naïve octopus was placed within sight of another octopus that had learned (through trial and error) how to open a puzzle box to obtain food, the naïve octopus was able to obtain the food reward in the same way – it had learned from another.</p>
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<h2>…and the ‘Houdini’ honey badger</h2>
<p>The honey badger is native to Africa and, although it eats a variety of food including meat and fruit, it favours honey that it is able to extract from beehives using its formidable claws. It is a remarkably tough – it will take on everything from snakes to <a href="http://www.dailymail.co.uk/news/article-2641503/He-went-swinging-Plucky-honey-badger-takes-pride-lions-15-times-size-holds-30-minutes.html">lions</a> – and the resourceful creature has also been known to use tools in the wild to obtain food. But the incredible footage of <a href="http://africageographic.com/blog/story-stoffel-honey-badger/">Stoffel the captive-bred honey badger</a> at Moholoholo Wildlife Rehabilitation Centre shows the astonishingly clever tool-use and behaviours he used to escape countless times from his enclosure. No wonder he was dubbed a <a href="http://www.bbc.co.uk/programmes/p01x412l">“Houdini”</a>.</p>
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<p>So, it would appear that many animals are indeed surprisingly clever. One day, they might even outwit us…</p><img src="https://counter.theconversation.com/content/59126/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Gentle works for Nottingham Trent University</span></em></p>Yes, apes and dolphins are bright. But what about the other animal Einsteins?Louise Gentle, Senior Lecturer in Behavioural Ecology, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/562792016-06-02T05:37:58Z2016-06-02T05:37:58ZBlocks and flocks: why are some bird species so successful in cities?<figure><img src="https://images.theconversation.com/files/124731/original/image-20160601-1923-13yar8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Worth crowing about? Birds that can problem-solve do best in cities.</span> <span class="attribution"><span class="source">Gypsytwitcher/shutterstock.com</span></span></figcaption></figure><p>Life in the city can be stressful – for birds just as much as people. For humans, cities are expressly designed to put roofs over heads and food within easy reach, but the opposite can be true for many urban birds. They can find food and shelter harder to come by in the concrete jungle – with some notable exceptions.</p>
<p>For any species in any habitat, survival is about problem-solving and adapting to the environment. So what street smarts do city birds need? And why do some species, such as lorikeets, crows and ravens, seem to dominate our urban landscapes?</p>
<p>In general, urban birds must be bolder than those that remain in natural habitats, as can be seen by the boldness (or “habituation”) with which some species will forage for food with people nearby. But they also need to be able to avoid or retreat from unfamiliar objects or situations if they seem dangerous. </p>
<p>City birds also need to withstand exposure to a wide range of pathogens. A <a href="http://beheco.oxfordjournals.org/content/27/2/637">study of birds in Barbados</a> found that urban birds have enhanced immune systems relative to their country counterparts. </p>
<p>While we have changed the environment in which some birds live, reducing resources in terms of food and shelter and increasing the number of pathogens that may impact their health, some birds have largely benefited from the new way of life.</p>
<h2>Winners and losers</h2>
<p>Within the urban ecosystem, there are winners and losers in the bird world. The suburban landscape, for example, now provides more nectar from flowers than native vegetation due to the gardens that people have established. This is a big help to nectar-feeding parrots such as <a href="http://www.birdlife.org/datazone/speciesfactsheet.php?id=1016467">Rainbow Lorikeets</a>. </p>
<p>A <a href="http://link.springer.com/article/10.1007/s11252-014-0417-5">recent study in Sydney</a> found that the lorikeets benefit from the increased abundance of flowers in urban areas, and their numbers were higher in the leafy suburbs than in bushland.</p>
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<a href="https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124912/original/image-20160602-1943-t9mvqp.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bold colours: Rainbow Lorikeets are among the most successful city birds.</span>
<span class="attribution"><span class="source">Kathryn Teare Ada Lambert</span>, <span class="license">Author provided</span></span>
</figcaption>
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<p>But if urban areas are such a rich source of nectar, why are some nectar-feeding species declining? </p>
<p>The <a href="https://theconversation.com/australian-endangered-species-regent-honeyeater-11294">Regent Honeyeater</a> feeds mainly on nectar and other plant sugars. It has been seen in orchards and urban gardens, but is listed as <a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=82338">critically endangered</a> by the federal government. </p>
<p>This is partly because widespread clearance of woodland habitat has led to the increase of the aggressive <a href="https://theconversation.com/why-we-hate-certain-birds-and-why-their-behaviour-might-be-our-fault-54404">Noisy Miner</a> and <a href="http://australianmuseum.net.au/red-wattlebird-anthochaera-carunculata">Red Wattlebird</a>. These species find it easy to “bully” other birds in open habitats. Noisy Miners have been observed pulling apart Regent Honeyeaters’ nests as they were being built. </p>
<p>Regent Honeyeaters, in contrast, are less adaptable to changed landscapes, because they are migratory and rely on detailed knowledge of existing food sources. If these resources are changed or removed, they may not have enough interconnected patches of habitat to move safely towards new resources – potentially leaving them vulnerable to cats, foxes and aggression from other birds. </p>
<p>Habitat loss can threaten some bird species or even leave them at risk of dying out if they do not locate alternative resources. The ability to find new food sources therefore becomes a valuable survival skill.</p>
<h2>What’s more useful: flexibility or intelligence?</h2>
<p>For some bird species, flexibility in finding food is crucial in making a successful switch to urban environments. One example is the <a href="http://www.birdlife.org/datazone/species/factsheet/22704983">Grey-crowned Babbler</a>, which is <a href="http://www.depi.vic.gov.au/__data/assets/pdf_file/0008/251189/Grey-crowned_Babbler_Pomatostomus_temporalis.pdf">endangered in Victoria</a>, but my colleagues and I have documented it living in a suburban area in <a href="http://www.kathrynlambert.com.au/uploads/6/2/3/1/62317591/lambert_et_al._2013.pdf">Dubbo, New South Wales</a>. </p>
<p>This species usually nests in coniferous woodland and forages in the leaf litter beneath the trees. But in Dubbo, we saw these birds feeding on lawns, in playgrounds and even in leaf litter along a train track at the back of urban housing, sometimes visiting backyards along the way. This suggests that these birds can survive the loss of their woodland habitat by being sufficiently adaptable to life in the suburbs – as long as they can continue to find enough food, disperse between nearby groups and have access to native nesting trees. </p>
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<a href="https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124913/original/image-20160602-1925-pit6pt.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">Grey-crowned Babblers can adapt to new landscapes.</span>
<span class="attribution"><span class="source">Kathryn Teare Ada Lambert</span>, <span class="license">Author provided</span></span>
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<p>For other species, such as <a href="https://theconversation.com/stone-the-crows-could-corvids-be-australias-smartest-export-4346">crows and ravens</a>, intelligence seems to be the key. These species can survive anywhere in the urban sprawl, including places where trees are scarce but rubbish bins are everywhere. Crows and ravens can literally pull food out of a bin and eat it – clearly a learned behaviour that has resulted from problem-solving. </p>
<p>These birds are highly opportunistic and social, allowing them to learn new ways of adapting to the almost complete removal of their natural environment.</p>
<h2>Survive and thrive</h2>
<p>What we can deduce from these examples is that some birds, like Rainbow Lorikeets and Grey-crowned Babblers, can adapt successfully to the urban sprawl as long as some characteristics of their habitat still remain. Other species, such as crows, have gone a step further and worked out how to survive purely on urban resources – effectively making a living in an environment that is completely unnatural to them. </p>
<p>This suggests that the more we urbanise an area without natural aspects, the less bird diversity we will have – and the more our urban areas will come to be dominated by those few species that are hardy, clever or adaptable enough to thrive. </p>
<p>Luckily, some councils in Australia and cities throughout the world are bringing the natural aspects of the forest back into the concrete jungle, so that a wider range of birds might survive here. More research is needed to work out exactly what each species will need, but <a href="https://theconversation.com/why-we-hate-certain-birds-and-why-their-behaviour-might-be-our-fault-54404">planting more native plants</a> is always a good start.</p><img src="https://counter.theconversation.com/content/56279/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kathryn Teare Ada Lambert 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>Why are our cities full of crows, ravens and rainbow lorikeets, while other species decline? The answer comes down to street smarts, adaptability, and sometimes plain bullying.Kathryn Teare Ada Lambert, Associate lecturer, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/502122015-11-06T04:23:15Z2015-11-06T04:23:15ZHow climate change is causing pied crow numbers to soar<figure><img src="https://images.theconversation.com/files/100923/original/image-20151105-16273-xh91ux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pied crow numbers are growing because of powerlines and climate change. This growth is distressing to some.</span> <span class="attribution"><span class="source">Peter Ryan</span></span></figcaption></figure><p>Pied crows, or <a href="http://www.oiseaux-birds.com/card-pied-crow.html">Corvus albus</a>, are a natural part of the landscape of southern Africa. They are bold, common, and familiar. But over recent years, especially in South Africa, there is evidence that there are <a href="http://onlinelibrary.wiley.com/doi/10.1111/ddi.12381/full">many more</a> of these birds.</p>
<p>The increase is worrying some <a href="http://karoospace.co.za/the-problem-with-pied-crows/">conservationists</a> who fear it could be having a negative impact on the local biodiversity. These fears have some merit given that the species is known to predate on birds’ nests and <a href="http://oo.adu.org.za/pdf/OO_2014_05_135-138.pdf">young tortoises</a>. Farmers are also concerned about the potential damage to <a href="http://groundup.org.za/article/where-lambs-have-no-eyes_3002">sheep flocks</a> because crows pluck out the eyes of the young lambs.</p>
<h2>The effect of changes in temperature</h2>
<p>Our <a href="http://onlinelibrary.wiley.com/doi/10.1111/ddi.12381/abstract">research</a> confirms that there has been an increase in pied crows in South Africa and quite dramatic changes in their centre of abundance. These changes vary throughout the country with large increases in the southwest but declines in the north and east of the country.</p>
<p>Second, our results suggest that these changes are closely linked to climate change.</p>
<p>Using data from two <a href="http://sabap2.adu.org.za/">bird atlases</a> carried out 20 years apart and linking these changes with information on the changing climate, we found that pied crows have increased mainly in the geographic areas of South Africa known as the <a href="http://www.southafrica.net/za/en/articles/entry/article-southafrica.net-the-magical-great-karoo">Karoo</a> and Fynbos shrublands which are distinctive types of vegetation of southwestern South Africa. This is where temperatures are warming. These biomes are relatively arid habitats consisting principally of short shrubs with very few natural trees.</p>
<p>The decline in numbers in the northwest of the country is most likely related to climate cooling in this region.</p>
<p>It appears that the crows are following a warming climate bubble into the southwest. <a href="http://onlinelibrary.wiley.com/doi/10.1111/ddi.12381/abstract">Our research</a> suggests pied crows have a preferred temperature range roughly equal to an average annual temperature of 19°C. We are approaching this in the southwest of South Africa at the moment, and the crows are loving it.</p>
<figure class="align-center zoomable">
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<figcaption>
<span class="caption">South Africa’s pied crows are moving to areas where the climate favours them more.</span>
<span class="attribution"><span class="source">Peter Ryan</span></span>
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</figure>
<p>Our results also suggest that this shift has been aided by the presence of power line infrastructure. This has provided sites for crows to build their nests in what is otherwise a virtually treeless landscape. </p>
<p>We conclude that while power lines have facilitated the increase of pied crows in the Karoo, climate change has driven their soaring numbers in these areas. The combination of climate change and electrical infrastructure has created the “perfect storm” of conditions to favour an explosion of pied crow numbers in the shrublands of South Africa.</p>
<h2>An unloved species</h2>
<p>Crows are big and obvious. Pied crows in particular are easy to identify with their white tank top plumage. These birds have had a bad rap globally. This dates back to medieval times when they were reviled as carrion birds on battlefields, or to superstitious associations of large, black birds with ill-omen or <a href="http://www.perspectivesmagazine.sk/news/ravens-and-crows-in-mythology-folklore-and-religion/">death</a>. </p>
<p>Their collective noun – a <a href="http://crow.bz/main/murder.htm">murder of crows</a> – doesn’t exactly do much for their public image. Given all this history, it is perhaps understandable that people react emotionally when they see crows doing what crows do best: being predators. </p>
<p>In South Africa pied crows are notorious, and viewed with great suspicion by urbanites and rural farmers alike. They are accused of such gory deeds as plucking the eyes from new born <a href="http://groundup.org.za/article/where-lambs-have-no-eyes_3002">lambs</a>, destroying the eggs of ground-nesting birds and decimating populations of <a href="http://oo.adu.org.za/pdf/OO_2014_05_135-138.pdf">tortoises</a>. </p>
<p>They’re also vilified for harassing other much more glamorous species, notably <a href="http://www.fitzpatrick.uct.ac.za/sites/default/files/image_tool/images/275/Publications/PDF_Archive/Africa_Birds_And_Birding/Author_Index/ABB16%285%2950-54.pdf">Verraux’s eagles</a>. Indeed these perceptions have led to calls for the control of pied crows by those who are worried about their negative impacts.</p>
<p>But these observations are not sufficient evidence to suggest that crows have an overwhelming negative impact on ecosystems. A recent scientific <a href="http://onlinelibrary.wiley.com/doi/10.1111/ibi.12223/abstract">review</a> suggests that in general, they don’t.</p>
<p>The truth is that their role within ecosystems is not necessarily so straight forward. For example, they also eat other predators, such as small snakes which can be a major cause of nest failure in <a href="http://www.umt.edu/mcwru/personnel/martin/PDF%20Martin/Influence%20of%20nestsite%20characteristics2004.pdf">Karoo birds</a>. Thus, increased numbers of pied crows certainly have the potential to change the balance of predator-prey interactions.</p>
<p>Given the situation, it may be that pied crows are an example of the relatively new phenomenon of the <a href="http://conservationbytes.com/2012/09/07/native-invaders-divide-loyalties/">native invader</a>. These are species that occur naturally in one area, but whose numbers suddenly increase out of all proportion with their surrounding ecosystems, shifting the balance of <a href="http://www.esajournals.org/doi/abs/10.1890/110060">nature</a> in unpredictable ways.</p>
<p>For a species to be considered a native invader in the truest sense it needs demonstrably to have a negative impact on other species. But while the pied crow clearly has such potential, we do not yet have the evidence to confirm they are causing declines of other species. Therefore, in assessing the pied crow “problem” we must be careful not to jump to <a href="http://www.westerncapebirding.co.za/conservation/368/blsa_position_statement_on_pied_crows">conclusions</a>. </p>
<h2>Climate change is ongoing</h2>
<p>Throughout the world, animals and plants are responding to the changing climate by shifting their ranges, changing their behaviour and changing their <a href="http://gyohe.faculty.wesleyan.edu/files/2010/11/Parmesan-Yohe-Nature.pdf">abundance</a>.</p>
<p>But climate change is ongoing, and so these shifts may continue to change over time. It is likely that we are not stepping into a new stable state but rather witnessing one step in a continual transition as species adjust or fail to adjust to conditions that are in a state of flux.</p>
<p>What happens next is uncertain. </p>
<p>As warming continues, will pied crow numbers in the south west of South Africa again subside? Or will they adapt to their new conditions? Either way, it is still unclear what the legacy of the “pied crow invasion” will be.</p><img src="https://counter.theconversation.com/content/50212/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Cunningham receives funding from the DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, University of Cape Town. </span></em></p><p class="fine-print"><em><span>Arjun Amar receives funding from the DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, University of Cape Town. </span></em></p>South Africa’s pied crows are moving to areas where the climate suits them more.Susan Cunningham, Lecturer, Percy FitzPatrick Institute, University of Cape TownArjun Amar, Senior Lecturer, Percy FitzPatrick Institute of African Ornithology, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/246112014-03-25T06:11:58Z2014-03-25T06:11:58ZShameless parasites perhaps, but cuckoos bring benefits to the nest<figure><img src="https://images.theconversation.com/files/44594/original/c3wqqcys-1395686847.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Anyone got any earplugs?</span> <span class="attribution"><span class="source">Daniela Canestrari</span></span></figcaption></figure><p>If you come across a young cuckoo this summer, you’ll be witness to one of the most bizarre sights in nature. Cuckoo chicks are interlopers in the nests of other species, and can be seen being frantically fed by their unwitting foster parent, despite often being clearly many times larger than their hosts. It makes you wonder: why on earth does this bird expend so much energy raising such clearly unrelated offspring? The clue comes from thinking about this puzzle in terms of costs and benefits.</p>
<p>Raising a cuckoo chick often occurs at the expense of host chicks. Common cuckoo chicks, for example, famously remove any host eggs or young from the nest within days of hatching. Chicks of a few other cuckoo species however will grow up alongside their host’s own offspring. Yet they still remove competition – magpie host chicks often die of starvation because, for example, <a href="http://www.bbc.co.uk/news/uk-wales-south-west-wales-26644756">great spotted cuckoo</a> chicks beg to be fed more intensely. </p>
<p>But parasitism may not always be costly. Great spotted cuckoos are also parasitical on carrion crows, but as crow chicks are much larger than cuckoos they are never out-competed and crow parents always manage to raise a few young of their own. For magpies, parasitism by cuckoos is costly, for crows it is less so.</p>
<p>So while magpies drive cuckoos away from their nest, or recognise foreign eggs and remove them, crows do not. But surely, even when costs are low, there is an evolutionary advantage to avoiding raising someone else’s chick.</p>
<p>In the late 18th century the German ornithologist Johann Bechstein presented a different idea. Instead of hosts being taken advantage of, he proposed that they were “beside themselves for joy” at the opportunity to raise a cuckoo chick. It was “an honour” to care for it. Modern biologists pooh-pooh this notion, because self-interest, not generosity, is the currency of evolution by natural selection. However, the <a href="http://www.aaas.org/news/science-parasitic-cuckoos-provide-nest-protection-crow-hosts">results of a 16-year study</a> published in the journal Science suggests he might have been on to something.</p>
<p>By looking at the relationship between these species differently, the study, led by <a href="http://www.unioviedo.es/UMIB/canestrari.html">Daniela Canestrari</a>, reveals that crows do not defend themselves because they actually benefit from having a cuckoo in the nest. Combining data collected over 16 years with careful field experiments, the study shows that nests containing cuckoos produce more crow chicks than those without. Better yet, the authors show how this entirely counter-intuitive conclusion is reached.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/44574/original/y84ww893-1395666307.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/44574/original/y84ww893-1395666307.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/44574/original/y84ww893-1395666307.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/44574/original/y84ww893-1395666307.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/44574/original/y84ww893-1395666307.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/44574/original/y84ww893-1395666307.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/44574/original/y84ww893-1395666307.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">
<figcaption>
<span class="caption">Don’t eat me, or I do this.</span>
<span class="attribution"><span class="source">Daniela Canestrari</span></span>
</figcaption>
</figure>
<p>When disturbed, great spotted cuckoo chicks emit copious amounts of a sticky, smelly substance. The authors tested the novel hypothesis that this stinky substance deters predators from the nest. If cats and hawks were given tasty pieces of chicken meat, but smeared with the cuckoo’s excretion, these typical nest predators were repelled. This indicates that the cuckoo’s excretion is a very powerful defence mechanism, likely to save both cuckoo and crow chicks alike if a predator comes calling.</p>
<p>So although crows appear to be behaving generously towards cuckoos, they are in fact still selfish – they tolerate cuckoos because of the benefit they provide their own young.</p>
<p>But do crows “welcome” cuckoos, as Bechstein suggested? It’s probably a little more complicated than this. Crows nest communally – their bushy nests often visible by the score in the bare branches of trees – and a previous study at this same field site showed that larger groups of crows’ nests are less likely to be parasitised by cuckoos. If raising a cuckoo is so beneficial to the survival of crow chicks, we’d expect the opposite. Perhaps having other crows to help raise chicks also helps to deter predators – the benefit of the cuckoo excretions no longer outweighs their cost.</p>
<p>Of those cuckoo species that do not evict their nest-mates, many also emit similar smelly fluids. So this study shows that it might be time to revisit our conclusions as to why their hosts have not evolved defences also. In areas where there are many predators, even the smallest advantage conferred by a cuckoo chick may be sufficient to obstruct the natural evolution of defences in the host species.</p>
<p>In the past when we have discovered brood parasite hosts with no apparent defences towards parasitism, we have come to a different conclusion. Perhaps these hosts will evolve defences, but there has not yet been sufficient evolutionary time to do so – the hosts are lagging behind. While plausible, such explanations are rarely satisfying as they are almost impossible to test or falsify. Daniela Canestrari and her colleagues however, have now done just this. Although smelly, theirs is a much more satisfying explanation.</p><img src="https://counter.theconversation.com/content/24611/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rose Thorogood receives funding from the Natural Environment Research Council UK (NERC) and a Society in Science - Branco Weiss fellowship.</span></em></p>If you come across a young cuckoo this summer, you’ll be witness to one of the most bizarre sights in nature. Cuckoo chicks are interlopers in the nests of other species, and can be seen being frantically…Rose Thorogood, NERC Independent Research Fellow, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/85032012-07-31T04:09:27Z2012-07-31T04:09:27ZFable or truth: are birds as brainy as children?<figure><img src="https://images.theconversation.com/files/13645/original/dpt6c94z-1343698241.jpg?ixlib=rb-1.1.0&rect=0%2C15%2C1131%2C791&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Birdbrains or copycats: Aesop's fable offers insight as to how children and birds think.</span> <span class="attribution"><span class="source">'Playingwithbrushes'</span></span></figcaption></figure><p>Humans are very good at innovating and it would seem reasonable to expect our children would be too. But a <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040574">recent study</a> questions these assumptions, suggesting young children’s ability to problem-solve is surpassed by birds. </p>
<p>When primatologist <a href="http://www.janegoodall.org/jane">Jane Goodall</a> first reported that chimpanzees strip leaves from twigs to fish for termites, archaeologist <a href="http://en.wikipedia.org/wiki/Louis_Leakey">Louis Leakey</a> famously responded: “Now we must redefine tool, redefine Man, or accept chimpanzees as humans”. Certainly, we can no longer lay claim to the title of the planet’s only tool-making animal.</p>
<p>Yet we remain without peer when one considers the depth, breadth, and inventiveness of our tool use. </p>
<p>There is every reason to believe that chimpanzees living 200 years ago stripped leaves from twigs, much as they do today. We, in contrast, have gone from building buggies for our horses to vehicles with an output roughly equivalent to that of 1,000 horses. </p>
<h2>The Crow and the Pitcher</h2>
<p>Imagine you are incredibly thirsty and you stumble across a pitcher of water, only to discover that the little water left at the bottom can’t be reached. What would you do? </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=745&fit=crop&dpr=1 600w, https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=745&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=745&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=937&fit=crop&dpr=1 754w, https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=937&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/13630/original/2j34nfj6-1343693925.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=937&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 Crow and the Pitcher From The Æsop for Children, illustrated by Milo Winter.</span>
<span class="attribution"><span class="source">Project Gutenberg etext 19994</span></span>
</figcaption>
</figure>
<p>This problem was famously played out in one of <a href="http://en.wikipedia.org/wiki/Aesop">Aesop</a>’s fables <a href="http://www.aesops-fables.org.uk/aesop-fable-the-crow-and-the-pitcher.htm">The Crow and the Pitcher</a>. The protagonist, a crow, worked out the solution: drop stones into the pitcher until the water rises high enough to be drunk. </p>
<p>As it turns out, corvids (the family crows belong to) can and will do this if presented with an <a href="http://www.sciencedirect.com/science/article/pii/S0960982209014559">analogous problem</a>. Rooks will drop stones into a thin perspex container, partially filled with water, in order to raise the level enough to retrieve a floating worm – although their behaviour in this scenario seems likely driven by [instrumental learning](http://ikt.hia.no/josejg/Papers/Modeling%20Instrumental%20Conditioning%20(HICSS'36%20paper.pdf) (learning that performance of particular actions increases the probability of a reward) rather than any deeper insight. </p>
<p>When presented with this problem, chimpanzees, our closest living animal relative, <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0019555">can work out a solution too</a>. </p>
<p>Given evidence that the mental abilities of young <a href="http://psycnet.apa.org/journals/bul/127/5/629/">children and chimpanzees are similar</a>, one would expect our offspring to master this test with ease. But they don’t.</p>
<h2>Fable or truth?</h2>
<p>In a study recently published in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040574">PLoS ONE</a>, Cambridge PhD student of Experimental Psychology <a href="http://cambridge.academia.edu/LucyCheke">Lucy Cheke</a> and her colleagues presented children aged between four and ten years with a series of tasks that required objects to be dropped into tubes of water to raise a floating object high enough to be retrieved. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=369&fit=crop&dpr=1 754w, https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=369&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/13634/original/3ghjrz29-1343694386.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=369&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Schematic of the apparatuses used in the PLoS ONE study.</span>
<span class="attribution"><span class="source">Lucy G. Cheke, Elsa Loissel, Nicola S. Clayton</span></span>
</figcaption>
</figure>
<p>In one task the children could choose to drop marbles into a tube of water or a tube of sawdust, both containing a token that could be exchanged for a sticker. </p>
<p>A second task presented children with one tube and a choice between two items to drop in – cork balls (which float and hence wont displace any water) or marbles. The third involved a complex u-shaped apparatus designed to obscure the way dropping items into the tube works to raise the water level. </p>
<p>Across these tasks a general pattern emerged. Whereas eight-year-olds generally worked out the solution straight away, children aged between five and seven years only learnt the correct response gradually over a number of repeated trials.</p>
<p>More alarmingly, four-year-olds never learnt the solution. When tested on the exact same task this puts the performance of the five to seven-year-olds at equivalence with <a href="http://www.oiseaux-birds.com/card-eurasian-jay.html">Eurasian Jays</a> and <a href="http://en.wikipedia.org/wiki/New_Caledonian_Crow">New Caledonian Crows</a> – and four-year-olds doing worse! </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1135&fit=crop&dpr=1 754w, https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1135&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/13635/original/n9jw6hm6-1343694664.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1135&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eurasian Jay.</span>
<span class="attribution"><span class="source">Jakub Hałun</span></span>
</figcaption>
</figure>
<p>This pattern of preschoolers doing poorly on such tasks is reflected in other research showing that, unlike <a href="http://creagrus.home.montereybay.com/corvids.html">corvids</a>, <a href="http://www.ianapperly.eclipse.co.uk/Beck%20et%20al%202011.pdf">young children can’t work out</a> to bend a pipe-cleaner into a hook in order to pull an item out of a tube. </p>
<p>To put it another way, the capacity of young children to recognise solutions to novel problems seems outstripped by our hairier cousins and some birdbrains.</p>
<h2>The faithful copycat</h2>
<p>So why do children perform so poorly? One possible reason is that, when confronted with an adult who presents a problem to be solved, it is not in the nature of our children to develop a solution themselves. Rather, they <a href="http://www.cbcd.bbk.ac.uk/people/scientificstaff/gergo/pub/index.html/csibra_gergely_2009.pdf">expect to be taught</a> – and then copy. </p>
<p>Indeed, children will copy with such devotion to replication fidelity that, in what has come to be known as <a href="http://rstb.royalsocietypublishing.org/content/364/1528/2417.short">overimitation</a>, children will reproduce causally redundant and ineffective actions used by an adult when achieving a specific outcome. </p>
<p>This is the case even if such actions compromise success, something that appears to be <a href="http://news.sciencemag.org/sciencenow/2010/05/kids-overimitate-adults-regardle.html">culturally universal</a>. </p>
<p>Work in my lab <a href="http://onlinelibrary.wiley.com/doi/10.1002/icd.1765/abstract">recently documented</a> how four-year-olds who couldn’t work out a version of the tube task described already were immediately able to do so following an adult’s demonstration – but they would copy exactly, even if the modelled method was inefficient.</p>
<p>At first glance, copying another’s obviously redundant actions seems maladaptive. It will extend the time taken to complete the task, possibly distract attention away from relevant components and may limit the extent to which anything learnt can be adapted to other situations and/ or objects. </p>
<p>But when one considers how children grow up in environments saturated with tools and objects they must learn to use, the value of high fidelity copying becomes clearer. As is the case with many cultural forms and skills, our tools and objects often lack perceptual information about the goal(s) for which they are being used. </p>
<p>That is, their uses are cognitively “opaque”, making it challenging for novices to identify which actions or behaviours are relevant and which are incidental. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/13638/original/t8w94wzj-1343695197.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">Turn. The. Power. Tool. Round. Buddy.</span>
<span class="attribution"><span class="source">roxeteer</span></span>
</figcaption>
</figure>
<p>Adopting a strategy based around exact copying may have fewer costs than attempting to selectively choose relevant components. Omitting a step in the process of preparing food, because it seems arbitrary, risks severe outcomes should the function of that step be to remove toxins. </p>
<p>It is part of human nature to faithfully copy the acts of other humans. This might get in the way of innovative behaviour in our young, but it also lays the foundation for the acquisition of a vast array of skills and behaviours that no individual would ever invent in his or her lifetime. </p>
<p>So on certain tasks the capacity of our young children to use their own insight to reach task solutions is outstripped by a grim and <a href="http://www.heise.de/ix/raven/Literature/Lore/TheRaven.html">ominous creature</a>, the raven. But while these birds might be born capable of flight they’ll never build a machine that can go from zero to 60kph in 2.6 seconds. </p>
<p>Now that’s flying! </p><img src="https://counter.theconversation.com/content/8503/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Nielsen receives funding from the Australian Research Council.</span></em></p>Humans are very good at innovating and it would seem reasonable to expect our children would be too. But a recent study questions these assumptions, suggesting young children’s ability to problem-solve…Mark Nielsen, Senior Lecturer at the School of Psychology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.