tag:theconversation.com,2011:/es/topics/birds-of-prey-11758/articlesBirds of prey – The Conversation2023-12-19T16:53:58Ztag:theconversation.com,2011:article/2199322023-12-19T16:53:58Z2023-12-19T16:53:58ZGrouse shooting in Scotland has an alarming death toll – and not just for game birds<figure><img src="https://images.theconversation.com/files/566557/original/file-20231219-27-8q5cdk.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3912%2C3125&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-grouse-lagopus-scotica-amongst-heather-397974433">Mark Caunt/Shutterstock</a></span></figcaption></figure><p>The Scottish moors are considered areas of outstanding beauty, and often assumed to be “wild” and “untamed”. However, these landscapes are the result of management techniques that are now under scrutiny by the Scottish government. </p>
<p>These practices include burning the moorlands (muirburn) and controlling the number of animals on the moors through trapping, snaring and poisoning. All of these measures are pursued to keep the number of red grouse artificially high so they can be shot in grouse season.</p>
<p>An estimated <a href="https://revive.scot/publication/hanged-by-the-feet-until-dead-an-analysis-of-snaring-and-trapping-on-scottish-grouse-moors/">260,000 animals</a> are killed each year in Scotland as part of these legal “predator control” measures. Targeted animals include <a href="https://www.britannica.com/animal/fox-mammal">foxes</a>, <a href="https://www.britannica.com/animal/weasel">weasels</a>, <a href="https://www.wildlifetrusts.org/wildlife-explorer/mammals/stoat">stoats</a>, <a href="https://www.britannica.com/animal/rat">rats</a>, <a href="https://www.britannica.com/animal/rabbit">rabbits</a> and various types of corvid like <a href="https://www.britannica.com/animal/crow-bird">crows</a>, <a href="https://www.britannica.com/animal/magpie">magpies</a>, <a href="https://www.britannica.com/animal/jackdaw">jackdaws</a> and <a href="https://www.britannica.com/animal/jay">jays</a>. </p>
<p>Many animals are also killed unintentionally. A <a href="https://revive.scot/publication/hanged-by-the-feet-until-dead-an-analysis-of-snaring-and-trapping-on-scottish-grouse-moors/">report</a> that was commissioned by the League Against Cruel Sports Scotland, a UK-based animal welfare charity, shows that as many as 39% of the trapped animals are not the intended target. These animals include <a href="https://www.wildlifetrusts.org/wildlife-explorer/mammals/pine-marten">pine martens</a>, <a href="https://www.britannica.com/animal/hedgehog-mammal">hedgehogs</a>, <a href="https://www.britannica.com/animal/badger">badgers</a>, <a href="https://www.britannica.com/animal/deer">deer</a> and <a href="https://www.britannica.com/animal/hare-mammal">hares</a>. But there have also been reports of endangered and protected animals, such as <a href="https://www.britannica.com/animal/falconiform">raptors</a> and the <a href="https://www.britannica.com/animal/capercaillie">capercaillie</a>, being killed.</p>
<p>In a recent <a href="https://www.league.org.uk/media/filer_public/03/1c/031cdbb4-847b-4cb8-8d3b-36197dc068e6/league_scotland_grouse_ethics_final.pdf">report</a>, which I co-authored with Dr Katie Javanaud and Professor Andrew Linzey from the Oxford Centre for Animal Ethics, we examined the moral basis for these practices. We found that it is impossible to overstate the severity of the suffering caused to animals caught in traps.</p>
<figure class="align-center ">
<img alt="The western capercaillie in a spruce forest." src="https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566553/original/file-20231219-15-5aengq.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">Some endangered and protected animals, like the capercaillie (pictured) are unintentionally killed.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/western-capercaillie-tetrao-urogallus-known-eurasian-2372812729">Jaroslav Macenauer/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Prolonged suffering</h2>
<p>The <a href="https://fur.ca/wp-content/uploads/2015/09/AIHTS-Copy-of-Agreement.pdf">Agreement on International Humane Trapping Standards</a>, to which the UK is a signatory, is the primary measure against which the welfare of trapped animals is judged. The standards consider traps to be “sufficient” and “efficient” if the animals are killed in anywhere between 45 seconds and five minutes. In fact, the standards still consider traps efficient if 20% of animals do not die within five minutes. </p>
<p>Any system of killing that only causes death after 45 seconds to five minutes is unnecessarily cruel. The animals suffer an appalling range of injuries that would not be acceptable in any other context. Entrapment for free-living animals is at best a distressing experience that obviously involves <a href="https://webarchive.nationalarchives.gov.uk/ukgwa/20130402141656/http:/archive.defra.gov.uk/wildlife-pets/wildlife/management/documents/snares-iwgs-report.pdf">psychological and emotional harm</a>.</p>
<p>All forms of predator control, whether that be trapping, snaring or poisoning, are predicated on exposing animals to hours or days of prolonged suffering. And all of this supposes that these traps can practically be inspected often. This is a question in and of itself given the vast area over which the methods are used and the limited manpower available, as well as adverse weather conditions. </p>
<h2>Stopping the suffering</h2>
<p>The suffering caused by these “management techniques” is also made invisible, reduced to being a private matter on private estates. However, cruelty to animals is a public moral issue and should be subject to political accountability.</p>
<p>Effective legislation requires three important components: compliance, inspection and enforcement. However, the illegal trapping of raptors indicates that there is limited compliance with the current legislation. </p>
<p>All raptors are protected under the <a href="https://www.legislation.gov.uk/ukpga/1981/69/contents">Wildlife and Countryside Act 1981</a>. But traps and poisons kill animals indiscriminately. So, as long as traps and poisons continue to be in use, legally protected animals like raptors will continue to be <a href="https://www.scottishraptorstudygroup.org/conservation/">caught and killed</a>.</p>
<figure class="align-center ">
<img alt="A golden eagle standing behind a clump of heather." src="https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566554/original/file-20231219-21-o7yxd4.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">All raptors are protected under the Wildlife and Countryside Act 1981.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/moorland-eagle-magnificent-golden-stands-behind-1056669830">Ian Duffield/Shutterstock</a></span>
</figcaption>
</figure>
<p>Raptor persecution is one of the main concerns of the Scottish government’s proposed <a href="https://www.parliament.scot/bills-and-laws/bills/wildlife-management-and-muirburn-scotland-bill">Wildlife Management and Muirburn Bill</a>. The bill aims to change “rules around how people can capture and kill certain wild birds and wild animals” and “rules around the making of muirburn”. </p>
<p>The government plans to address these problems by licensing the use of traps and giving the Scottish Society for Prevention of Cruelty to Animals (SSPCA) powers of inspection, as well as introducing a licensing scheme for grouse hunting and the management of land. </p>
<p>It also intends to bring in an outright ban on <a href="https://www.rspca.org.uk/adviceandwelfare/wildlife/deterrents">glue traps</a>. These traps consist of a small board coated with a sticky adhesive, a practice the RSPCA argue causes “unacceptable cruelty”. </p>
<h2>We need to do more</h2>
<p>The plan to introduce powers of inspection for the SSPCA should be commended. But licensing the killing of animals on Scotland’s moors serves only to codify and ingrain the suffering and deaths of those animals. </p>
<p>All current methods of “predator control” either cause (often prolonged) suffering or make animals liable to suffering. To license any of the traps currently in use is to institutionalise the suffering and death of thousands of animals a year.</p>
<p>Our report concludes that predator control is uncontrollable. There simply are not the mechanisms in place to control it. Poisons and traps of various kinds are readily available for purchase in shops and on the internet. There is no moral alternative to making all of these practices illegal.</p>
<p>We propose the promulgation of a new charter for free-living animals. Scotland could lead the way in pioneering legislation that protects all animals, domestic and free-living. This legislation should begin with the recognition of sentience and enshrine in law the value and dignity of wild animals such that their right to live unmolested is respected.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Clair Linzey is the deputy director of the Oxford Centre for Animal Ethics. The report the article is based on, "Killing to Kill: An Ethical Assessment of “Predator Control” on Scottish Moors," is a report of the Oxford Centre for Animal Ethics. The report was commissioned by the League Against Cruel Sports to produce an independent review of the ethics of “predator control” on Scottish moors. The League is not a neutral bystander in the debate about grouse shooting, of course, but it is to its credit that it was prepared to commission independent academic research on this topic. While we have requested research information from the League, it has at no point sought to place restrictions on the nature and type of our deliberations, or the nature of our conclusions. Our work has been considerably improved with the help of two independent academic peer reviewers. We gratefully acknowledge the many academics, intellectuals, and writers who have indicated their public support for this report.
</span></em></p>The welfare of wild animals is severely compromised to sustain grouse shooting in Scotland.Clair Linzey, Research Fellow in Animal Ethics, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2163582023-11-16T19:03:39Z2023-11-16T19:03:39ZGiant eagles and scavenging vultures shared the skies of ancient Australia<figure><img src="https://images.theconversation.com/files/555992/original/file-20231026-21-xbm5tb.jpg?ixlib=rb-1.1.0&rect=11%2C0%2C7507%2C3686&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A flock of vultures (_Cryptogyps lacertosus_) and Australian ravens watch and wait (left), as an adult eagle _Dynatoaetus pachyosteus_ feeds on the carcass of a dead _Diprotodon_ (centre), while a younger bird seeks to join in. In the nearby treetops, a second adult _D. pachyosteus_ feeds its hungry chick (right).</span> <span class="attribution"><span class="source">John Barrie</span></span></figcaption></figure><p>Today, Australia is home to 17 species of hawks and eagles. But the fossil record shows some other, rather special raptors were present in the relatively recent past. </p>
<p>Tens of thousands of years ago, Australia was home to species such as <a href="https://theconversation.com/australias-extinct-giant-eagle-was-big-enough-to-snatch-koalas-from-trees-200341"><em>Dynatoaetus gaffae</em>, the largest eagle ever to have lived in Australia</a>, and <a href="https://theconversation.com/it-was-long-thought-these-fossils-came-from-an-eagle-turns-out-they-belong-to-the-only-known-vulture-species-from-australia-187017"><em>Cryptogyps lacertosus</em>, our only known vulture</a>. </p>
<p>Now, we have discovered another ancient eagle shared the skies with these prehistoric predators. In a <a href="https://doi.org/10.1080/03115518.2023.2268780">new paper in the journal Alcheringa</a>, we describe the formidable <em>Dynatoaetus pachyosteus</em>, based on fossils found in the Naracoorte Caves in South Australia.</p>
<h2>A new eagle unearthed</h2>
<p><em>Dynatoaetus pachyosteus</em> (the name means “powerful eagle with thick bones”) lived during the Pleistocene (a time period spanning from 2.5 million to 11,700 years ago). It had a wingspan similar to that of a wedge-tailed eagle, but with much more robust and powerful wings and legs. It was slightly smaller than its cousin, the massive <em>Dynatoaetus gaffae</em>. </p>
<p>This formidable predator would most likely have preyed on medium to large marsupials and birds. It may even have attacked juveniles and weakened individuals of huge megafaunal species like the <a href="https://theconversation.com/fossil-find-reveals-giant-prehistoric-thunder-birds-were-riddled-with-bone-disease-173745">giant flightless bird</a> <em>Genyornis</em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of an eagle feeding a chick, together with photos of four bones." src="https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556402/original/file-20231028-30-aal6zi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&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 large extinct eagle <em>Dynatoaetus pachyosteus</em> (left) and comparison of its humerus or upper arm/wing bone (centre) to that of a modern female wedge-tailed eagle (right). Scale bar = 10mm.</span>
<span class="attribution"><span class="source">John Barrie (reconstruction) / Ellen Mather (photos)</span></span>
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<p><em>Dynatoaetus pachyosteus</em> shared the Pleistocene landscape with at least two other large eagles, the huge <em>Dynatoaetus gaffae</em> and the wedge-tailed eagle we know today. For these species to coexist, they would have likely needed to have slightly different ecological roles to avoid outright competition. </p>
<p>“Niche separation” typically occurs by <a href="https://www.nature.com/scitable/knowledge/library/resource-partitioning-and-why-it-matters-17362658/">exploiting different kinds of food or habitats</a>. These three eagles most likely coexisted by specialising in hunting different prey and nesting in different places.</p>
<p>The occurrence of both species of the <em>Dynatoaetus</em> genus in Australia (and nowhere else) has implications for the evolution of eagles. <em>Dynatoaetus gaffae</em> and <em>D. pachyosteus</em> presumably evolved from a common ancestor in Australia that diverged into two species, a process that typically takes a very long time. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australias-extinct-giant-eagle-was-big-enough-to-snatch-koalas-from-trees-200341">Australia's extinct giant eagle was big enough to snatch koalas from trees</a>
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<p>This suggests the ancestor of this genus was already ensconced on our continent millions of years before the two Pleistocene species arose. <em>Dynatoaetus pachyosteus</em> and <em>D. gaffae</em> together form a rare example of a raptor genus diversifying into multiple species entirely on the Australian continent (what scientists call “endemic evolutionary radiation”). </p>
<p>There are only two raptor genera today restricted to Australia, and both consist of only a single species: <em>Hamirostra</em> (the black-breasted buzzard) and <em>Lophoictinia</em> (the square-tailed kite).</p>
<h2>Primitive vultures of ancient Australia</h2>
<p>Our research has also revealed intriguing new information about another extinct raptor, the vulture <em>Cryptogyps lacertosus</em>. </p>
<p>Fossils from the Green Waterhole (also known as Fossil Cave), in the Tantanoola district near Mt Gambier, give us a more complete picture of this species. We found several paired wing bones, two shoulder bones, a vertebra and a toe bone, all probably from a single individual. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/it-was-long-thought-these-fossils-came-from-an-eagle-turns-out-they-belong-to-the-only-known-vulture-species-from-australia-187017">It was long thought these fossils came from an eagle. Turns out they belong to the only known vulture species from Australia</a>
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<p>The additional bones of <em>Cryptogyps</em> indicate it was a rather primitive vulture, less adapted for the long periods of soaring flight characteristic of modern vultures.</p>
<p>Thanks to the sediment around the fossils, we also have a very precise date of when <em>Cryptogyps</em> was alive. Many of the Green Waterhole fossils were buried in a deposit of calcite rafts – crystals that form on the surface of still bodies of water in caves. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photos of several bones and an illustration of a vulture-like bird" src="https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=689&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=689&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=689&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=866&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=866&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556401/original/file-20231028-24-5h6thl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=866&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fossil bones from the wing and shoulder of the extinct vulture <em>Cryptogyps lacertosus</em>, recovered from Green Waterhole, South Australia. Scale bar = 50mm. Life reconstruction top right.</span>
<span class="attribution"><span class="source">Ellen Mather (photos) / John Barrie (reconstruction)</span></span>
</figcaption>
</figure>
<p>Today, most of the cave is submerged because of a high water table, but in the past, it was mostly dry. A pool of water deeper in the cave was where these calcite rafts formed. </p>
<p>The water was likely what attracted animals into the cave in the first place. These animals then died, and their bones sank to the bottom of the pool along with the calcite rafts. Our team dated these calcite rafts – and thus the entombed <em>Cryptogyps</em> fossils – at approximately 60,000 years old.</p>
<h2>Mammal extinctions affect birds of prey</h2>
<p>When we think of the <a href="https://theconversation.com/did-people-or-climate-kill-off-the-megafauna-actually-it-was-both-127803">mass extinction</a> of Australian megafauna, we tend to think about the demise of large mammals, such as the “giant wombat” <em>Diprotodon optatum</em>, the “marsupial lion” <em>Thylacoleo carnifex</em>, and the giant short-faced kangaroo <em>Procoptodon goliah</em>. Some large reptiles are also commonly recognised as victims: the giant goanna (Megalania) <em>Varanus priscus</em>, the constricting snake <em>Wonambi naracoortensis</em>, and <a href="https://theconversation.com/meet-the-biggest-and-most-bizarre-skink-ever-found-in-australia-it-became-extinct-47-000-years-ago-206764">even a giant armoured skink</a> <em>Tiliqua frangens</em>.</p>
<p>But as we can see from the case of our large eagles and vultures, other groups of animals were also affected. Birds of prey, especially large and scavenging species, <a href="https://www.semanticscholar.org/paper/The-Late-Pleistocene-Continental-Avian-extinction-Tyrberg/6cfc6bfea30c8b5635d5250eede1556c4d654402">went extinct around the world during the Late Pleistocene</a>, their food supply likely affected by the loss of large mammalian species. Australia appears to have been no exception to the rule.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two photos of eagles in flight, one with a white belly and the other with dark, patterned wings." src="https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=476&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=476&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556394/original/file-20231028-27-4hz9e1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=476&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 wedge-tailed eagle (<em>Aquila audax</em>) and the white-bellied sea eagle (<em>Icthyophaga leucogaster</em>) are the largest birds of prey found in modern Australia.</span>
<span class="attribution"><span class="source">Michael Lee</span></span>
</figcaption>
</figure>
<p>The new fossils reveal many of Australia’s large birds of prey did not survive the megafaunal extinction event in the Late Pleistocene, roughly 50,000 years ago. The two largest species that managed to persist to the present are the wedge-tailed eagle, which is a generalist hunter found throughout the continent, and the white-bellied sea eagle, which targets fish and has a coastal distribution. </p>
<p>It is likely our three extinct large raptors – two giant eagles and a vulture – were too specialised as hunters and scavengers of megafauna to adapt to a rapidly changing world. Their extinction likely caused a further cascade of effects through the ecosytem: in Asia, for instance, more recent loss of vultures has led to increased populations of scavenging feral dogs and higher prevalance of <a href="https://www.sciencedaily.com/releases/2022/02/220214095744.htm">diseases such as rabies</a>.</p><img src="https://counter.theconversation.com/content/216358/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ellen K. Mather received funding from BirdLife Australia Raptor Group.</span></em></p><p class="fine-print"><em><span>Michael Lee receives funding from the Australian Research Council, Flinders University and the Royal Society of South Australia</span></em></p><p class="fine-print"><em><span>Trevor H. Worthy has received funding from The Australian Research Council for research on fossil birds. He has previously worked for Flinders University and now has an adjunct status there.</span></em></p>New fossils reveal Australia was once home to a much greater diversity of huge eagles and vultures, which died off alongside ‘giant wombats’ and ‘marsupial lions’.Ellen K. Mather, Adjunct Associate Lecturer in Palaeontology, Flinders UniversityMike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders UniversityTrevor H. Worthy, Associate Professor, Vertebrate Palaeontology Group, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2121842023-08-25T05:19:28Z2023-08-25T05:19:28ZRat poison is killing our beloved native owls and tawny frogmouths – and that’s the tip of the iceberg<figure><img src="https://images.theconversation.com/files/544711/original/file-20230825-15-cf4fu6.jpg?ixlib=rb-1.1.0&rect=37%2C5%2C3251%2C2357&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/eastern-barn-owl-south-australia-2205796803">Imogen Warren, Shutterstock</a></span></figcaption></figure><p>There’s nothing quite like having a rodent problem in your home. Most people will do anything to get rid of them. </p>
<p>Australians usually reach for rat poison, without a second thought. Most of these poisons – sold at supermarkets and hardware stores – are “<a href="https://apvma.gov.au/node/87226#what-is-an-anticoagulant-rodenticide">second-generation anticoagulant rodenticides</a>” (SGARs) also known as single-dose anticoagulants. These extremely powerful poisons stay in the body for many months. It takes only a single feed to kill a rodent, usually within a week. </p>
<p>With the rodent problem solved, our house is once again our castle, and all is well. Right? </p>
<p>Unfortunately, use of rat poison is leading to the wide-scale poisoning of Australia’s nocturnal predatory birds, including the crowd favourite tawny frogmouth and Australia’s largest owl, the majestic powerful owl. <a href="https://www.sciencedirect.com/science/article/pii/S0048969723049185#bb0020">Our new research</a> reveals the alarming extent of the problem. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/MAGjJJxtQeI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Help save owls from rodenticide poisoning (BirdLife Australia)</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-control-invasive-rats-and-mice-at-home-without-harming-native-wildlife-180792">How to control invasive rats and mice at home without harming native wildlife</a>
</strong>
</em>
</p>
<hr>
<h2>Poisoning in tawny frogmouths and owls</h2>
<p>Anticoagulant rat poisons are effective at killing rodents, but they also accumulate in the liver and muscle tissues of predators that eat the poisoned animals. </p>
<p>The SGARs do not kill immediately, it can take many days. During that time, the rodent – or any other animal that eats the poison – can keep eating more. The poison does not leave the body but continues to accumulate in tissues while attacking the body’s capacity to clot blood. Eventually the poisoned animal dies from internal bleeding. </p>
<p>While still alive, the poisoned animal makes easy prey because it becomes lethargic and doesn’t behave in a normal, cautious manner.</p>
<p>Eating a single poisoned rodent probably won’t kill a predator, but what happens when predators are exposed to poisoned prey all the time? This is probably what is happening in our cities, suburbs and farms, every day of the year.</p>
<h2>Here’s what we found</h2>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0048969723049185#bb0020">Our new research</a> reveals alarming levels of rat poisons in our nocturnal predatory birds. Across four species, we found a staggering 92% of the 60 dead birds we tested had been exposed to these poisons. The concentration of SGARs in the liver was such that toxic or lethal impacts were likely to have occurred in 33% of powerful owls we tested, 68% of tawny frogmouths, 42% of southern boobooks and 80% of barn owls.</p>
<p>Testing for rat poison is not a pretty job. The only accurate way is to test the animal’s liver. Over the last two years, our team had the gruesome job of collecting and dissecting the livers of 60 dead owls and tawny frogmouths (24 powerful owls, 19 tawny frogmouths, 12 southern boobooks, and five eastern barn owls). Most birds were from Victoria. We were aided by concerned citizens who found and reported these dead birds to us, often collecting the bodies themselves and keeping them in their fridges.</p>
<p>Of the 55 birds found to have rodenticides in them, every one contained brodifacoum. Brodifacoum is the most widely available SGAR in Australia. It is highly potent and can stay in the body for more than 100 days. That means animals can accumulate more in their bodies as they continue to eat poisoned prey. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mouse-plague-bromadiolone-will-obliterate-mice-but-itll-poison-eagles-snakes-and-owls-too-160995">Mouse plague: bromadiolone will obliterate mice, but it'll poison eagles, snakes and owls, too</a>
</strong>
</em>
</p>
<hr>
<h2>Are we also poisoning other native animals?</h2>
<p>Our research shows poisoning rodents is poisoning our predators, in large numbers. This is widespread across urban areas, agricultural areas and forests on the edge of suburbia.</p>
<p>Given the high rate of exposure to rat poisons, it is likely predator populations will decline. Losing our predators to poisoning will have widespread consequences, for natural systems and urban environments. Birds of prey help to keep rodents (and other species prone to reaching high numbers) in check. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photograph looking up at a powerful owl eating a common brushtail possum while in a tree" src="https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=709&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=709&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=709&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=891&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=891&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544443/original/file-20230824-23-wudpy8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=891&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A powerful owl eating a common brushtail possum.</span>
<span class="attribution"><span class="source">John White</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We are probably inadvertently poisoning other native animals. Powerful owls do not eat many rats, they prefer to dine on native possums and gliders. The common brushtail possum, with its broad diet and penchant for living in roof cavities, is no doubt directly feasting on rat poison.</p>
<p>So the high level of rat poison we found in nocturnal predators is likely the tip of a poisoned iceberg.</p>
<h2>Is this a new ‘Silent Spring’ moment?</h2>
<p>In 1962, biologist Rachel Carson’s book Silent Spring introduced the world to the impacts of pesticides on humans and non-target species. This catalysed investigations into pesticides such as DDT, which were being passed up the foodchain and “bio-accumulating” in raptors, decimating populations. Now, the devastating impacts of SGARs are becoming more widely recognised. </p>
<p>Our research, along with a growing body of <a href="https://www.jstage.jst.go.jp/article/jvms/81/2/81_17-0717/_article">international evidence</a>, highlights the need to introduce restrictions on the availability of SGARs in Australia. </p>
<p>As with DDT in the 1980s, many countries such as the <a href="https://www.epa.gov/rodenticides/restrictions-rodenticide-products">United States</a>, <a href="https://www2.gov.bc.ca/gov/content/environment/pesticides-pest-management/legislation-consultation/rodenticide-ban">Canada</a> and the <a href="https://www.thinkwildlife.org/stewardship-regime/">United Kingdom</a> are moving to ban public access to SGARs or substantially restrict how they can be used.</p>
<p>But Australia is lagging on the effective regulation on the use of SGARs. Currently, SGARs are <a href="https://apvma.gov.au/node/87226#what-is-an-anticoagulant-rodenticide">approved for use</a> “in and around domestic, commercial, industrial and agricultural buildings”. They are not approved for use in crops, in the open, or in other areas accessible to non-target animals or children. But these restrictions are not sufficient. It is also likely many people do not follow instructions when they use rat poisons. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tawny frogmouth with its head to one side, looking serious" src="https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=352&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=352&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=352&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=443&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=443&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544442/original/file-20230824-19-rnjxqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=443&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of Australia’s favourite birds, the tawny frogmouth.</span>
<span class="attribution"><span class="source">John White</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/spooky-stealthy-night-hunters-revealing-the-wonderful-otherworld-of-owls-209498">Spooky, stealthy night hunters: revealing the wonderful otherworld of owls</a>
</strong>
</em>
</p>
<hr>
<h2>What are the alternatives to rat poison?</h2>
<p>Next time you reach for the rat poison, consider the consequences. There is a very strong likelihood you will poison more than rodents – you could be poisoning a tawny frogmouth or owl. </p>
<p>Try to approach the problem without using poisons. In particular, avoid any SGAR-based products (those containing brodifacoum, bromadiolone, difenacoum, difethialone and flucoumafen as the active ingredients). </p>
<p>There are ways to control rats and mice <a href="https://theconversation.com/how-to-control-invasive-rats-and-mice-at-home-without-harming-native-wildlife-180792">without harming native wildlife</a>. Trapping technology has come a long way and the latest methods are far more effective, humane and efficient than the old-fashioned spring-loaded mouse trap.</p>
<p>We can also make our homes less attractive to vermin, by clearing vegetation close to the house, reducing the availability of food sources such as pet food and compost, and blocking access to the building. And of course, we can support our natural predators to do what they do best, without putting themselves in harm’s way.</p><img src="https://counter.theconversation.com/content/212184/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>There’s shocking new evidence of rodenticide poisoning in Australia’s nocturnal predatory birds. High concentrations of the active ingredients were found in 92% of the 60 dead birds they tested.John White, Associate Professor in Wildlife and Conservation Biology, Deakin UniversityRaylene Cooke, Associate Professor, Deakin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2013962023-03-10T16:01:05Z2023-03-10T16:01:05ZHow COVID lockdowns triggered changes in peregrine falcon diets – and what this means for urban pest control<figure><img src="https://images.theconversation.com/files/514683/original/file-20230310-104-4p8lml.jpg?ixlib=rb-1.1.0&rect=14%2C0%2C4910%2C3288&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pigeons are a key source of food for the peregrine falcon.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/peregrine-falcon-spreading-wings-1658591701">Sriram Bird Photographer/Shutterstock</a></span></figcaption></figure><p>Many people <a href="https://theconversation.com/covid-19-reshaped-the-way-we-buy-prepare-and-consume-food-193069">saw their eating habits change</a> during the COVID-19 lockdowns. Some ate more frequently or experimented with healthier recipes. Others ordered more deliveries. </p>
<p>But human diets weren’t the only ones to change. In a <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1002/pan3.10445">recent study</a>, we found that lockdown triggered changes in the diets of London’s peregrine falcons. London is home to as many as <a href="https://www.nhm.ac.uk/discover/peregrine-falcons-and-their-city-success.html">30 breeding pairs of peregrines</a> (one of the world’s largest urban populations).</p>
<p>The emergence of high-definition web cameras now means that scientists can record every bit of food that peregrines feed to their young. Our team of 50 citizen scientists analysed live stream footage from peregrine nests across 27 English cities to determine what the birds were eating. We observed the nests throughout the 2020-2022 breeding seasons, allowing us to track the changes to their diets that occurred during and outside of lockdown periods.</p>
<p>In London, peregrines ate a lower proportion of feral pigeons (-15%) during the lockdowns. Instead, they caught more <a href="https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/starling-family/#:%7E:text=A%20family%20of%20small%20birds,wings%20and%20sharply%2Dpointed%20bills.">starlings</a> (+7%) and <a href="https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/ring-necked-parakeet/">ring-necked parakeets</a> (+3%).</p>
<p>Peregrine falcons depend on prey animals like pigeons for food. But, as pigeon populations themselves are contingent on humans, peregrines are vulnerable to changes in human activities. Our results demonstrate that humans are a key, but underappreciated, part of the ecology of urban environments.</p>
<h2>Bird watching, for science</h2>
<p>Pigeons – which descended from the cliff-dwelling <a href="https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/rock-dove/">rock dove</a> – have adopted our cities as their homes. In highly urbanised cities, humans support feral pigeons both intentionally and otherwise through the production of litter and food waste. These pigeons are now present in such vast numbers across London that <a href="https://londonist.com/2016/07/where-did-trafalgar-square-s-pigeons-come-from">feeding them is banned</a> in particular locations, including Trafalgar Square. </p>
<p><a href="https://www.meridianracingpigeons.com/raptorreport.pdf">Around 13 million</a> racing pigeons are also released into the wild in the UK each year – and some of them will turn up in our cities. Birds of prey subsequently catch <a href="https://www.rspb.org.uk/our-work/policy-insight/species/birds-of-prey-in-the-uk/racing-pigeons-and-birds-of-prey/">8% of these pigeons</a>. Yet, the importance of racing pigeons to the diet of urban peregrines remains uncertain. </p>
<p>When pandemic restrictions were imposed, the pigeon racing season was suspended and these birds were confined to their lofts. Feeding opportunities for feral pigeons also dwindled in urban areas as people were advised to stay at home. This forced hungry pigeons to spread out in search of alternative food sources, meaning fewer pigeons were present for peregrines to feed on. </p>
<p>The wide geographic coverage of our study also revealed that the effects of social restrictions on peregrine diets were uneven across the UK. London was the only city studied where the proportion of pigeons eaten dropped significantly. Across the other cities studied, pigeons took 0.3% more pigeons on average during lockdown periods than outside of them – an insignificant change.</p>
<p>This is likely due to London’s particularly large non-residential central area. The city’s core emptied as people stopped commuting and the <a href="https://www.nber.org/system/files/working_papers/w28876/w28876.pdf">food and retail sector ground to a halt</a>. So London’s pigeons had to cover more ground than their counterparts in smaller cities to reach residential areas where people could still feed them.</p>
<figure class="align-center ">
<img alt="Empty Westminster Bridge with the Houses of Parliament and the Big Ben in the background." src="https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514661/original/file-20230310-462-fo17aa.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">Central London shut down during the COVID-19 lockdowns.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/empty-westminster-bridge-houses-parliament-big-242576479">pcruciatti/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Rethinking pest control</h2>
<p>Large pigeon flocks that are drawn to humans in parks or squabble over food waste at litter bins are familiar sights for city dwellers. We take these daily interactions for granted or see them as pests. But pigeons contribute to the success of apex predators like the peregrine falcon.</p>
<p>Pigeons are subject to pest control programmes globally. Countries like Singapore and Switzerland have opted to manage pigeon populations by targeting their human food sources. For example, the Swiss city of Basel <a href="https://www.nytimes.com/1993/02/09/science/science-watch-basel-solves-problem-of-too-many-pigeons.html">halved its street pigeon population</a> between 1988 and 1991 by prohibiting their feeding.</p>
<p>These measures are often imposed to improve public hygiene. <a href="https://www.jstor.org/stable/3782800">Research</a> has found that pigeons can pass infectious diseases like <a href="https://www.gov.uk/guidance/psittacosis">ornithosis</a> and <a href="https://www.ncbi.nlm.nih.gov/books/NBK567794/#:%7E:text=The%20Paramyxoviridae%20is%20a%20family,respiratory%20syncytial%20virus%20(RSV).">paramyxovirus</a> onto humans through their droppings. </p>
<p>Their excrement is also corrosive and can cause substantial damage to buildings. In 2003, the then Mayor of London Ken Livingston said pigeon droppings had caused <a href="http://news.bbc.co.uk/1/hi/england/london/3275233.stm">up to £140,000 worth of damage</a> to Nelson’s Column and other monuments in Trafalgar square. </p>
<p>But pigeon management overlooks the needs of the wildlife that share our cities. Our study offers a glimpse into how these efforts may have consequences for apex predators particularly in large cities, where the raptors may be more vulnerable to swings in the population of their pigeon prey. </p>
<p><a href="https://www.berghahnjournals.com/view/journals/nature-and-culture/12/2/nc120202.xml">Previous research</a> found that measures to control rat populations in the eastern US city of Philadelphia in 2013 forced red-tailed hawks to switch to eating pigeons, which they are poorly suited to catching. While London’s peregrines had starlings and parakeets as backup prey during lockdown, raptors in cities worldwide face the growing pressure of their prey being eradicated to protect humans from disease.</p>
<figure class="align-center ">
<img alt="A red tailed hawk in flight." src="https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514662/original/file-20230310-20-93l8iu.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">The red tailed hawk – a bird of prey that is found through North America.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-tailed-hawk-flying-close-718914187">Justin Buchli/Shutterstock</a></span>
</figcaption>
</figure>
<p>Given the importance of pest species to urban falcons, we must consider what could happen to urban raptor populations if these “undesirable” pest species are eradicated. The ecological impacts of the COVID-19 lockdowns remind us that we are part of urban ecosystems. Perhaps it’s time to reconsider how we co-exist with urban animals, working with rather than against them.</p><img src="https://counter.theconversation.com/content/201396/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brandon Mak received research funding from the British Trust for Ornithology and King's College London for this study. </span></em></p><p class="fine-print"><em><span>Ed Drewitt received a small grant from the British Trust for Ornithology to support the purchase of some equipment that supported this study.</span></em></p>Lockdown wasn’t good news for London’s peregrine falcons.Brandon Mak, PhD student in the Department of Geography, King's College LondonEd Drewitt, PhD student studying the diet of urban peregrines, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2008642023-03-02T06:07:02Z2023-03-02T06:07:02ZWhy prey animals often see threats where there are none – and how it costs them<p>For a nervous horror fan, an evening watching HBO’s hit post-apocalyptic television show The Last of Us might be followed by a restless night under the duvet. The silhouette of a coat slung over the back of a chair or even the screeching of a cat in the garden will cause a spike of adrenaline. </p>
<p>Animals are primed to be wary through natural selection rather than scary television shows, but like humans, they often make mistakes when watching out for threats. </p>
<p>Identifying stealthy predators is already a difficult task. From the perspective of a songbird, a harmless crow flying overhead may look similar to a raptor. But predator identification is made more challenging by the fact that prey animals often juggle multiple activities like foraging, keeping an eye on competitors and courting mates, all at the same time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The silhouettes of a buzzard and a crow in the air." src="https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=395&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=395&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512849/original/file-20230301-14-5fs2sk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=395&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Smaller birds often mistake crows and raptors from beneath.</span>
<span class="attribution"><span class="source">smittenkittenorig/flickr, Michal Hantl/flickr & Martyn Fletcher/flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>This can be made easier by working as a group. Members of a school of fish, flock of birds or herd of antelope can share the task of watching out for predators. When an animal detects a predator, they share this information with other group members directly, by producing a warning, or inadvertently, by preparing to flee. The group as whole can then respond by fleeing, hiding or adopting a defensive position.</p>
<p>But this information is not always reliable. <a href="https://link.springer.com/article/10.1007/s10336-006-0081-5">Over half</a> of the anti-predator responses of <a href="https://www.wildlifetrusts.org/wildlife-explorer/birds/waterfowl/greylag-goose">greylag geese</a> flocks occur when no predator is nearby. </p>
<p>The false alarm rate for South America’s <a href="https://ebird.org/species/gcoroc1">Guianan cock-of-the-rock</a> birds <a href="https://academic.oup.com/auk/article/104/3/496/5192914?login=true">exceeds 70%</a>. And more than three quarters of the responses of <a href="https://academic.oup.com/beheco/article/21/3/584/220325?login=true">semipalmated sandpipers</a> and <a href="https://www.jstor.org/stable/4535716?seq=3#metadata_info_tab_contents">willow tits</a> arise due to the misidentification of harmless stimuli as predators. </p>
<p>These mistakes can be costly in terms of lost foraging and resting time and wasted energy. But what causes these false alarms and how can animals avoid them?</p>
<h2>The likelihood of a false alarm</h2>
<p>In a <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12932">recent article</a>, we reviewed research on predator misidentification and found that false alarms are common throughout the animal kingdom. We found that the propensity for animals to produce false alarms varies depending on three main factors: </p>
<ol>
<li><p>how clear the predator cues are</p></li>
<li><p>the vulnerability of prey to predation</p></li>
<li><p>the cost of performing alarm or escape behaviour. </p></li>
</ol>
<p>When predators are harder to identify, perhaps because they are well camouflaged, an animal may be more likely to mistake unrelated sounds or movements for a predator. <a href="https://www.sciencedirect.com/science/article/pii/S0960982208010191">Research</a> found that bumblebees were more likely to produce false alarms having previously been exposed to highly camouflaged <a href="https://en.wikipedia.org/wiki/Misumena_vatia#Habitat_and_distribution">goldenrod crab spiders</a> than bees that were unaccustomed to them. </p>
<p>Some species are instead simply more vulnerable to predators than others. This can be because they are not fast enough to escape a close encounter or not equipped to fight a predator off. For these species, ignoring a true alarm is more likely to result in death, so it may be beneficial to follow a “better-safe-than-sorry” principle and pay the cost of being occasionally wrong. </p>
<p><a href="https://www.jstor.org/stable/4535716?seq=3#metadata_info_tab_contents">Willow tits</a> produce alarm calls in response to most large aerial objects including planes and crows. This is because they are typically hunted in ambush attacks in which they are unlikely to escape. So the costs of alarm calling at a few planes becomes dwarfed by the threat of being killed in an attack. </p>
<p>In some circumstances, the cost of fleeing unnecessarily is higher and an animal may require more certainty about the risk posed by a potential threat before taking evasive action. </p>
<p><a href="https://academic.oup.com/beheco/article/21/3/584/220325?login=true">Semipalmated sandpipers</a> can double their body mass during staging (where birds stock up on resources before migrating), which means that flight will require substantially more energy. False alarms were found to be less common later in staging when body mass was higher and escape flights were more costly. </p>
<figure class="align-center ">
<img alt="A large flock of birds flying over water." src="https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512842/original/file-20230301-16-2q0zn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A large flock of Semipalmated Sandpipers in New Brunswick, Canada.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/large-flock-semipalmated-sandpipers-calidris-pusilla-1363319669">Justin Dutcher/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Who should be trusted?</h2>
<p>False alarms raise a dilemma for animals that live in groups.</p>
<p>If they respond to potential threats too often, they waste energy and the opportunity to perform other activities crucial to their survival. Greylag geese, for example, lose <a href="https://link.springer.com/article/10.1007/s10336-006-0081-5">19 minutes</a> of foraging time on average during a false alarm. With multiple false alarms each day, this time adds up to a substantial loss of food. </p>
<p>But if animals ignore ambiguous cues too often, they risk a true predator attack and could be killed. Animals therefore employ a range of strategies to prevent the spread of false information through their groups. </p>
<p>In some species of <a href="https://link.springer.com/article/10.1007/s002650100414">rodent</a>, <a href="https://peerj.com/articles/7572/">corvid</a> and primate, animals will remember which individuals have been unreliable in the past and will stop responding to their alarms. </p>
<p>In 1988, researchers played <a href="https://www.sciencedirect.com/science/article/abs/pii/S0003347288800186?via%3Dihub">two different calls</a> made by the same unreliable signaller to a group of vervet monkeys. The monkeys, who had learned to ignore one type of call made by the unreliable signaller, also ignored an acoustically different call made by the same individual.</p>
<figure class="align-center ">
<img alt="Four vervet monkeys sitting in a tree." src="https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512848/original/file-20230301-16-g403ad.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">Vervet monkeys learn to ignore alarm calls from unreliable group mates.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/vervet-monkeys-cercopithecus-aethiops-sitting-tree-31992718">EcoPrint</a></span>
</figcaption>
</figure>
<p>Many species also use a strategy called consensus decision making. If only one group mate raises an alarm, it is more likely to be false than if multiple members raise the same alarm. In this case, the group will take evasive action only if a certain number of group members respond to the information. </p>
<p>Groups of <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2000.1064">common redshanks</a>, a wading bird found in the UK and Europe, will respond immediately if multiple birds produce an escape flight simultaneously. But when only a single bird makes an escape flight, other group members will first scan the environment to assess the validity of the alarm before acting. </p>
<p>Responses to threats, real or imagined, have an impact on the survival of prey species. But the balancing act of separating true from false alarms clearly influences how animals weigh up and respond to information from their group mates.</p><img src="https://counter.theconversation.com/content/200864/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Webster works for the University of St Andrews. He receives funding from various academic and research organisations. </span></em></p><p class="fine-print"><em><span>Leah Gray 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>False alarms are common in prey animals, but what causes them and how can they be avoided?Leah Gray, PhD in Conservation Science, University of AberdeenMike Webster, Lecturer, School of Biology, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1941752022-12-04T08:54:46Z2022-12-04T08:54:46ZA dangerous pesticide isn’t being monitored in key bird of prey populations - we’re shedding light on that gap<figure><img src="https://images.theconversation.com/files/497025/original/file-20221123-24-5lmmwa.jpg?ixlib=rb-1.1.0&rect=612%2C15%2C2328%2C1215&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">GettyImages</span></span></figcaption></figure><p>It was once regarded as a <a href="https://www.swissinfo.ch/eng/ddt--from-miracle-chemical-to-banned-pollutant/3253684">miracle chemical</a> to protect against disease and improve global food production. The man who discovered its properties even won a <a href="https://www.britannica.com/biography/Paul-Hermann-Muller">Nobel Prize for medicine</a>. But today, <a href="https://www.britannica.com/science/DDT">dichlorodiphenyltrichloroethane</a> (DDT) is best known for its devastating effects on the environment, as well as on animal and human health. </p>
<p>It was first used in the second world war to protect Allied soldiers against malaria and typhus, which are spread by mosquitoes and body lice. After the war, DDT became a widely available pesticide to kill insect crops pests and insects causing disease in humans. </p>
<p>However, it became clear that DDT was toxic to more than its intended targets. Continued exposure to the chemical <a href="https://www.cdc.gov/biomonitoring/pdf/ddt_factsheet.pdf">can cause</a> neurological damage, endocrine disorders and reproductive failure in both humans and animals. </p>
<p>Awareness of this damage was in no small part due to Rachel Carson’s book <a href="http://www.rachelcarson.org/SilentSpring.aspx">Silent Spring</a>, published in 1962. Silent Spring brought global attention to DDT’s environmental impacts and sparked a public outcry that forced much of the developed world – the “global north” – to ban the use of DDT in the 1970s and 1980s.</p>
<p>In 2004 the <a href="http://www.pops.int/">Stockholm Convention</a> on Persistent Organic Pollutants – those that stay in the environment for a long time after use – was adopted by over 90 nations. DDT was among the most dangerous pesticides, industrial chemicals and by-products placed on the convention’s “dirty dozen” list, and was banned in most parts of the world.</p>
<p>Two years later the World Health Organization <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1570869/">recommended</a> the restricted use of DDT to control malaria. It <a href="http://npic.orst.edu/factsheets/ddtgen.pdf">remains in use</a> for this purpose in various tropical countries in Asia, Africa, and South and Central America. Its use here doesn’t just put human health at risk: top predators, among them <a href="https://www.britannica.com/animal/bird-of-prey">birds of prey</a> (also referred to as raptors), are threatened too.</p>
<h2>Birds of prey as sentinels</h2>
<p>Birds of prey or raptors are often apex predators, sitting at the top of the food chain. As such, they can act as an “ecological barometer”, helping us gauge the health of the environment. In addition to their value as indicator species, they provide valuable ecosystem services, controlling pest animals such as rodents and removing carrion from the environment, potentially reducing the spread of disease. </p>
<p>Because DDT accumulates in wildlife and magnifies up the food chain many raptor populations have been nearly <a href="https://www.jstor.org/stable/2401613#metadata_info_tab_contents">wiped out</a> by its use. However, this <a href="https://www.nationalgeographic.org/activity/biomagnification-and-bioaccumulation/">bio-accumulation</a> also means they have the potential to serve as a useful indicator to monitor levels of DDT in the environment. Thus, raptors can be regarded as sentinels for DDT.</p>
<p>There has been extensive monitoring of DDT in raptors by conservation agencies and academics across the globe for the last 60 years. But no study has looked at the patterns emerging from these monitoring programmes, nor compared these patterns through space and time. Our <a href="https://www.sciencedirect.com/science/article/pii/S0048969722068346">new study</a> fills that gap. </p>
<h2>A global north bias</h2>
<p>We found that DDT monitoring in raptors is heavily biased toward the global north. Europe and North America account for 95% of samples. This is a concern because most DDT use is currently in the global south, as are most raptor species. </p>
<p>We found that DDT has been measured in over 27,000 raptors across more than 100 species. The numbers of birds sampled peaked in the 1960s and 1970s, an increase that coincided with international concern surrounding DDT.</p>
<p>However, just three species account for half of all raptor samples collected: bald eagle, Eurasian sparrowhawk and peregrine falcon. Only the peregrine falcon occurs on all continents, but have been sampled far less in Africa, Asia, Central and South America than Europe and North America. The Eurasian sparrowhawk is also found in Asia but similar to the peregrine has been sampled far less frequently there than in Europe.</p>
<p>The geographical one-sidedness <a href="https://tspace.library.utoronto.ca/bitstream/1807/71107/1/Tackling%20Inequities%20in%20Global%20Scientific%20Power%20Structures.pdf">we’ve identified</a> can likely be linked to a dearth of available funding, appropriate infrastructure and the necessary training in global south nations.</p>
<p>And it’s worrying for three reasons. </p>
<p>First, <a href="https://reader.elsevier.com/reader/sd/pii/S0006320718305871?token=BE5B91A7D1D04D803F09245532FF85F05E7C3CC99FD685A3963349EE2107B039AB93376274699582A842DCBC230F5AAE&originRegion=us-east-1&originCreation=20221115162212">most current DDT use</a> is in the global south because of the chemical’s role in malaria control. </p>
<p>Second, the region is <a href="https://reader.elsevier.com/reader/sd/pii/S0006320718305871?token=BE5B91A7D1D04D803F09245532FF85F05E7C3CC99FD685A3963349EE2107B039AB93376274699582A842DCBC230F5AAE&originRegion=us-east-1&originCreation=20221115162212">home to most</a> of the world’s raptors. Most raptor species <a href="https://www.pnas.org/doi/epdf/10.1073/pnas.2018203118">come from</a> South and Southeast Asia, followed by sub-Saharan Africa and South America. The tropics in particular (mostly in the global south) display the <a href="https://www.pnas.org/doi/epdf/10.1073/pnas.2018203118">highest</a> raptor diversity. There are also many declines of species in these <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320718300934">regions</a>.</p>
<p>Third, many countries in the global south are notoriously <a href="https://www.adb.org/sites/default/files/publication/514476/adbi-wp980.pdf">poor enforcers</a> of environmental legislation.</p>
<h2>More gaps to fill</h2>
<p>Even with better enforcement, global north countries are not always good at protecting their environments. It was only when peregrine falcons were wiped out from many regions of the <a href="https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/peregrine/population-numbers-and-trends/">UK</a> and the <a href="https://kids.frontiersin.org/articles/10.3389/frym.2022.714834">US</a> – in the late 1950s to mid 1960s – that their governments finally acted by banning DDT.</p>
<p>As more data are being gathered and collated to develop a clearer picture of DDT levels among <a href="https://doi.org/10.1016/j.envpol.2017.09.059">raptors</a> in the global south, countries in the region might learn from the US and UK measures and prepare similar programmes to start monitoring DDT levels in their raptor populations in a more systematic manner.</p>
<p>Our research is a critical first step in consolidating the uneven information on the global monitoring of DDT. The next step will be to compare how DDT levels in raptors from tropical regions still using DDT compare to levels in raptors from more temperate regions where DDT has long been banned. We are currently working on that research. </p>
<p>As more data becomes available and a clearer picture is created, we hope governments will feel compelled to act to ensure we do not face a second “silent spring”.</p><img src="https://counter.theconversation.com/content/194175/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kailen Padayachee received funding from the National Research Foundation and Carnegie Corporation of New York. </span></em></p><p class="fine-print"><em><span>Arjun Amar receives funding from the South African National Research Foundation (NRF) . </span></em></p><p class="fine-print"><em><span>Chevonne Reynolds 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>DDT accumulates in wildlife and magnifies up the food chain. Birds of prey occupy the top of these food chains in various ecosystems.Kailen Padayachee, PhD Candidate, FitzPatrick Institute, University of Cape Town and Research Fellow, School of Animal, Plant and Environmental Sciences, University of the WitwatersrandArjun Amar, Associate Professor , FitzPatrick Institute of African Ornithology, University of Cape TownChevonne Reynolds, Senior Lecturer, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1912262022-09-27T15:26:01Z2022-09-27T15:26:01ZPeril ahead for red kite chicks born during times of drought<figure><img src="https://images.theconversation.com/files/486759/original/file-20220927-24-pbqng9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2673%2C1780&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-red-kite-milvus-spread-wings-1504693928">Werner Baumgarten/Shutterstock</a></span></figcaption></figure><p>Take a drive down England’s M40 motorway and chances are you’ll see a large bird with a forked tail overhead searching for roadkill: the red kite.</p>
<p>The conservation status of this species has looked promising in recent years. Assessments made between 2005 and 2019 classified red kites as “near threatened” on the <a href="https://www.iucnredlist.org/species/22695072/181651010">IUCN Red List</a>, a global system for classifying each species’ extinction risk. Population growth throughout large swathes of the red kite’s range meant that the species was bumped up to “least concern” in 2020. </p>
<p>The UK’s growing population of red kites is largely a result of their <a href="https://www.rspb.org.uk/our-work/conservation/conservation-and-sustainability/safeguarding-species/case-studies/red-kite/">reintroduction</a> to parts of England and Scotland beginning in 1989. This is often hailed as a <a href="https://naturalengland.blog.gov.uk/2020/07/21/a-conservation-success-story-the-reintroduction-of-red-kites-30-years-ago/">conservation success story</a>. And rightly so. The number of red kites has soared (pun intended) by a whopping <a href="https://www.bto.org/sites/default/files/publications/bbs_report_2021.pdf">1,935%</a> between 1995 and 2020 across the UK.</p>
<p>While things are generally looking up for the species at a global level, populations in some countries, including Spain, France, Portugal and Slovakia are <a href="https://ec.europa.eu/environment/nature/conservation/wildbirds/action_plans/docs/milvus_milvus.pdf">declining</a>. Some of the causes of these declines have existed for centuries, such as hunting. </p>
<p>But <a href="https://www.nature.com/articles/s41467-022-33011-7">a new study</a> has revealed how climate change poses a hidden threat by permanently damaging the development of chicks born during droughts. This could undermine the recovery of the species and is a sobering reminder of the challenges that a warming world will confront species with, even those which seem to be doing well for the time being.</p>
<h2>A hidden threat</h2>
<p>Some of the effects of drought on wildlife are predictable. Drought conditions restrict water and food and hence, nutrition, forcing animals to work harder to meet their basic needs and remain healthy. Other effects can take years to become apparent.</p>
<p>In the new study, researchers used data from as far back as 1970 to assess how red kites hatched during a drought fared in later life. The authors tagged nestlings with a unique leg ring and monitored their survival over many years. </p>
<figure class="align-center ">
<img alt="Three young birds of prey surrounded by twigs." src="https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=482&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=482&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486768/original/file-20220927-14-f4rvnu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=482&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Young red kites hunker down in a Berlin nest.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Red_kite#/media/File:Milmil_njg_980613.jpg">Accipiter/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The authors concluded that some chicks born during a drought year, like 2022 in <a href="https://www.bbc.co.uk/news/science-environment-62298430">England and Wales</a>, continued to face the consequences as adults. This might be because their development is permanently impaired due to a failure to meet their nutritional needs in early life; potentially making them smaller, more vulnerable to disease, and less capable of hunting.</p>
<p>Mounting threats put pressure on populations over time. As these populations begin to shrink due to the death rate exceeding the number of births, they can eventually enter a vortex: the population continues to decline until it goes extinct. This has happened once before with the British population. </p>
<p>Beginning in the 16th century, legal and illegal killings reduced red kite numbers. The bird’s increasing rarity made it a prime target for taxidermists and <a href="https://www.rspb.org.uk/birds-and-wildlife/advice/wildlife-and-the-law/wild-bird-crime/egg-collecting/">egg collectors</a>, particularly in the Victorian era. By the late 1980s, red kites were extinct in England and Scotland. This highlights how older threats may conspire with new ones to reverse recent progress.</p>
<figure class="align-center ">
<img alt="Two beige eggs with brown speckles." src="https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486769/original/file-20220927-18-a0mn8r.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Red kite eggs in a German natural history museum collection.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Red_kite#/media/File:Milvus_milvus_MWNH_0750.JPG">Klaus Rassinger & Gerhard Cammerer/Museum Wiesbaden</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Helping species adapt</h2>
<p>Red kites were considered vermin across Britain and Ireland during the 16th century and their numbers were <a href="https://www.jstor.org/stable/20764411#metadata_info_tab_contents">rigorously controlled</a>. While public perceptions have changed, gamekeepers and farmers still illegally shoot, poison and trap red kites for the perceived harm they cause to livestock and game. In 2020 alone, 20 red kites were confirmed to have been <a href="https://www.rspb.org.uk/about-the-rspb/about-us/media-centre/press-releases/birdcrime-2020/">killed this way</a> in the UK (and those are just the ones we know about).</p>
<p>As well as being efficient hunters, red kites feed on animal carcasses. This leaves them vulnerable to <a href="https://pbms.ceh.ac.uk/sites/default/files/PBMS_Rodenticide_Red_Kite_2016_FINAL.pdf">secondary poisoning</a>: they may scavenge an animal killed using toxic substances, such as a mouse or rat, which pass to the predator.</p>
<p>Like other birds of prey, red kites have been known to <a href="https://www.sciencedirect.com/science/article/abs/pii/S000632071200290X?casa_token=oiLHhY3WxdcAAAAA:ArPfTVdg6qL82wSC3WuL8pQJnwo6N0up2rMb9RxaNUbqTgU9Dnzf3gLaEAnsXR-N53ajHmK5iHU">fatally collide</a> with wind turbines, which may affect populations on a local level. As large-bodied birds that glide while scouring the ground for prey, red kites may fail to spot the blades before it is too late. </p>
<p>As the climate changes, new threats are emerging that scientists are only beginning to understand, such as <a href="https://theconversation.com/human-disruption-to-earths-freshwater-cycle-has-exceeded-the-safe-limit-our-research-shows-182562">more frequent and severe droughts</a>. The findings of this study highlight the importance of being proactive when approaching a species’ conservation. </p>
<p>But <a href="https://www.sciencedirect.com/science/article/pii/S0006320722000775">there is hope</a> that some measures, such as <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2011.02532.x">providing shade over nests</a> to protect young from severe heat and providing <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1474-919X.2008.00844.x">extra water</a> when rain is scarce can help life partially adapt to the upheaval wrought by climate change.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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</figure>
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<p class="fine-print"><em><span>Esther Kettel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research traces the effect of drought on red kite chicks born during particularly dry years.Esther Kettel, Senior Lecturer in Ecology and Conservation, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1870172022-07-19T20:29:58Z2022-07-19T20:29:58ZIt was long thought these fossils came from an eagle. Turns out they belong to the only known vulture species from Australia<figure><img src="https://images.theconversation.com/files/474759/original/file-20220719-16-4osyy5.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C2991%2C1989&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The extinct species may have been a relative of the living Griffon Vulture (pictured). </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>In 1905, a fragment of a fossil wing bone discovered near the Kalamurina Homestead, South Australia, was described as an extinct eagle and named <em>Taphaetus lacertosus</em>, meaning “powerful grave eagle”. </p>
<p>Now <a href="https://doi.org/10.11646/zootaxa.5168.1.1">research</a> published by myself and <a href="https://theconversation.com/profiles/trevor-h-worthy-172603">my</a><a href="https://theconversation.com/profiles/mike-lee-8293">colleagues</a> can reveal this species was no eagle at all. It was an “Old World” vulture, which we have renamed <em>Cryptogyps lacertosus</em>, or “powerful hidden vulture”.</p>
<p>This is the first time one of these scavenging raptors has been found to have lived in Australia. Living more than tens of thousands of years ago, we believe <em>Cryptogyps</em> likely died out with ancient Australia’s megafauna. There’s much about the species we’ve yet to find out.</p>
<figure class="align-center ">
<img alt="A woman in a lab with fossil bones" src="https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474379/original/file-20220716-24-h5v98o.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">Here’s me at the Flinders University palaeontology lab, holding the fossil vulture tarsus (left) and a tarsus of a living vulture species (right).</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>A puzzling absence</h2>
<p>Vultures are birds of prey that feed almost exclusively on decaying flesh. They play a vital role in their ecosystems by speeding up the consumption of carcasses. In this way, they assist in redistributing nutrients, and help limit the spread of diseases. </p>
<p>They can be divided into two groups. “New World” vultures inhabit North and South America and belong to their own distinct family. “Old World” vultures are found in Africa, Europe and Asia, and belong to the same family as eagles and hawks.</p>
<p>Considering they’re so widespread today, it’s surprising vultures long appeared absent from Australia. It’s even stranger when you look at the fossil record across South-East Asia, where vulture fossils have been found as far south as the Indonesian island of Flores. Surely they could have flown a little further?</p>
<p>What’s more, the Australian environment would have been well-suited to support vultures until about 50,000 years ago. Back then, megafaunal marsupials were widespread and abundant across the continent, and would have provided plentiful carcasses for scavengers.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-giant-kangaroo-once-roamed-new-guinea-descended-from-an-australian-ancestor-that-migrated-millions-of-years-ago-185778">This giant kangaroo once roamed New Guinea – descended from an Australian ancestor that migrated millions of years ago</a>
</strong>
</em>
</p>
<hr>
<h2>The shape of a scavenger</h2>
<p>We aren’t the first to consider there might be vultures in Australia’s fossil record. Other palaeontologists have previously suggested some Australian bird fossils could belong to vultures, and the Kalamurina “eagle” was one such example.</p>
<p>My colleagues and I wanted to find out if this really was the case, and so we began comparing the fossil bones of <em>Cryptogyps</em> to a wide range of living birds of prey, including vultures.</p>
<p>Being scavengers, vultures have a very different musculature and bone structure to eagles. This fact proved to be crucial in confirming <em>Cryptogyps lacertosus</em> was indeed a vulture. </p>
<figure class="align-right ">
<img alt="Tarsi of Wedge-tailed eagle and fossil vulture" src="https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=783&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=783&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=783&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=984&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=984&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474404/original/file-20220717-14-u3tkt6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=984&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A silhouette size comparison of a Wedge-tailed Eagle (left) and <em>Cryptogyps lacertosus</em> (right), and tarsi comparisons of both below.</span>
<span class="attribution"><span class="source">Ellen Mather, Wedge-tailed Eagle silhoutette derived from photo by Vicki Nunn.</span></span>
</figcaption>
</figure>
<p>The material used in our research included the original wing bone from the Kalamurina Homestead, two identical wing bone fragments from the Wellington Caves in New South Wales, and two “tarsi” (lower leg bones) – one from Wellington Caves and the other from Leaena’s Breath Cave in Western Australia. All of these bones are thought to belong to <em>Cryptogyps</em>.</p>
<p>Close examination of the bones, and comparison to eagles and vultures from around the world revealed their muscle scars and structure are more vulture-like than eagle-like, especially for the tarsi. This strongly indicates they belonged to a scavenger.</p>
<p>To further test this, we placed the fossils in an evolutionary tree with other birds of prey. Our results confirmed what the comparison suggested: <em>Cryptogyps</em> was indeed a vulture, and potentially a close relative of the Griffon Vulture found across Europe and Asia.</p>
<h2>The life and death of a species</h2>
<p>Based on the leg bones, we can infer <em>Cryptogyps</em> didn’t actively hunt and grab prey with powerful talons. Rather, it would have scavenged dead animals as vultures do now. </p>
<p>At this point in time, we don’t have enough of the skeleton to know exactly what <em>Cryptogyps lacertosus</em> looked like, or what it ate.</p>
<p>It could have been a social species, gathering in large flocks around the corpses of megafauna such as <em>Diprotodon</em> or <em>Protemnodon</em>. Or perhaps it was a solitary bird, searching and feeding alone, or in pairs. It may have fed on the soft insides of the body, or may have preferred the tougher muscle and skin.</p>
<p>Gaining this information will require more discoveries in the future. What isn’t in question, however, is that like all vultures today <em>Cryptogyps lacertosus</em> would have played an important role in ecosystem health.</p>
<p>Fossils of <em>Cryptogyps</em> are believed to date from the Middle to Late Pleistocene, somewhere between 770,000 and 40,000 years ago. Its extinction was very likely related to the demise of Australia’s megafauna around 60,000–40,000 years ago.</p>
<p>As large-bodied animals died off, the supply of carcasses scavengers need to survive would have dwindled significantly. Starvation would have become common, breeding attempts less successful and eventually the total population would have fallen below the threshold needed to survive. </p>
<p>Other more generalist raptors such as Wedge-tailed Eagles and Black Kites subsequently filled the reduced scavenging niche.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Camera is zoomed in on the top half of a Wedge-tailed Eagle" src="https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474757/original/file-20220719-91509-9h3rmq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Wedge-tailed Eagle is the largest bird of prey in Australia today.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Australia has the sobering distinction of being the only continent to lose its vultures entirely. Sadly, around half of all living vultures today are endangered and under threat of extinction. </p>
<p>And the <a href="https://education.nationalgeographic.org/resource/role-scavengers-carcass-crunching">consequences</a> of <a href="https://www.sciencedaily.com/releases/2016/05/160505145035.htm">this decline</a> have been dire, including increased disease transmission in both animal and human populations, potential impacts on the nutrient cycle, and the restructuring of ecosystems. </p>
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<strong>
Read more:
<a href="https://theconversation.com/the-endangered-condor-surprised-researchers-by-producing-fatherless-chicks-could-virgin-birth-rescue-the-species-170965">The endangered condor surprised researchers by producing fatherless chicks. Could 'virgin birth' rescue the species?</a>
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<img src="https://counter.theconversation.com/content/187017/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ellen K. Mather 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>The identification of a vulture that lived more than 50,000 years ago is shedding more light on biodiversity loss and ecosystem change in Australia.Ellen K. Mather, Adjunct associate lecturer, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1644002021-08-26T18:13:00Z2021-08-26T18:13:00ZWho would win in a fight between a wedge-tailed eagle and a bald eagle? It’s a close call for two nationally revered birds<figure><img src="https://images.theconversation.com/files/417995/original/file-20210826-23-1xbv48d.png?ixlib=rb-1.1.0&rect=47%2C41%2C3892%2C1916&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Wes Mountain/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>This article is part of the “<a href="https://theconversation.com/au/topics/who-would-win-in-a-fight-103258">Who would win?</a>” series, where wildlife experts dream up hypothetical battles between predators (all in the name of science).</em></p>
<hr>
<p>America’s most-loved bird versus a scrappy Aussie scavenger. In a clash that might rival Crocodile Dundee in New York City, here we’ll pit two iconic birds of prey against one another: the wedge-tailed eagle and the North American bald eagle. </p>
<p>As a disclaimer, this exercise is well and truly hypothetical. <a href="https://birdlife.org.au/bird-profile/wedge-tailed-eagle">Wedge-tailed eagles</a> are native to Australia and would never encounter a bald eagle, which has a range covering most of North America, in the wild. </p>
<p>This is probably why they can both exist in the healthy numbers on both continents: their similar niches would likely result in high levels of competition for resources such as food and nesting sites, especially sites close to the ocean. </p>
<p>In fact, wedgies, Australia’s largest raptor, have such few competitors, they’ve actually taken on the role played by vultures and condors in the rest of the world: that of scavenger. While <a href="https://www.nationalgeographic.com/animals/birds/facts/bald-eagle">bald eagles</a> will also scavenge large prey, their speciality is fish.</p>
<p>So before we get into the details of the fight (and, potentially, a diplomatic incident), let’s learn more about these two enormous birds of prey.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414508/original/file-20210804-17-1qovgvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The bald eagle is the national emblem for the US.</span>
<span class="attribution"><span class="source">Alvaro Postigo/Unsplash</span></span>
</figcaption>
</figure>
<h2>Their fan base</h2>
<p>Both species are thankfully doing well in terms of numbers, which is great news for humans because they play important roles. They clean up carrion and keep numbers of rapidly reproducing small mammals in check — think rabbits, mice, rats. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/who-would-win-in-a-fight-between-an-octopus-and-a-seabird-two-marine-biologists-place-their-bets-158520">Who would win in a fight between an octopus and a seabird? Two marine biologists place their bets</a>
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<p>They are both also very important in the culture of Indigenous people on both continents. In Australia, many Aboriginal Dreaming stories include the wedge-tailed eagle, especially in depictions of Bunjil the creator, and some have even <a href="http://aboriginalastronomy.blogspot.com/2012/05/eagle-dreaming.html">associated constellations with it</a>. In native North American cultures, bald eagle feathers are <a href="https://blog.nativehope.org/the-feather-symbol-of-high-honor">highly esteemed</a>, symbolising bravery, strength and holiness.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414512/original/file-20210804-21-1iyd03o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wedge-tailed eagles are scavengers, and are often seen feasting on road kill.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The birds’ sheer size means they are easily recognised in their native ranges, making them apt emblems. </p>
<p><img src="https://cdn.theconversation.com/static_files/files/1758/Bald-Eagle.gif?1629958259" width="30%" align="left"></p>
<p>Of course, the bald eagle has the honour of being the United States’ <a href="https://www.livescience.com/32811-why-is-the-bald-eagle-americas-national-bird-.html">national bird</a>, appearing on its coat of arms. The wedge-tailed eagle is an emblem in the Northern Territory, and appears on the Royal Australian Air Force <a href="https://www.airforce.gov.au/about-us/your-air-force/brand/badge">badge</a>. </p>
<p>Each country also has one professional football team named after the respective birds: The Philadelphia Eagles in the US, and the West Coast Eagles in Australia’s AFL. </p>
<p>So despite <a href="https://www.theflindersnews.com.au/story/6161276/eagle-is-landing/">historical conflict</a> with humans <a href="https://www.kezi.com/content/news/Oregon-ranchers-blame-eagles-for-livestock-deaths-510470391.html">blaming the birds</a> for losses to livestock, they both have a pretty strong fan base today. </p>
<p>While both eagles are part of the same family group (Accipitridae), they are not very closely related, belonging to different genera. </p>
<p><img src="https://cdn.theconversation.com/static_files/files/1759/Wedgie.gif?1629960314" width="30%" align="right"></p>
<p>The wedge-tailed eagle (<em>Aquila audax</em>) fits in a group sometimes referred to as “true eagles”, which also holds some of the most widespread eagles in the world, such as the golden eagle (<em>Aquila chrysaetos</em>). </p>
<p>Bald eagles (<em>Haliaeetus leucocephalus</em>), on the other hand, belong in the <em>Haliaeetus</em> genus, a group of predominantly fish-eating birds of prey that includes Australia’s own white-bellied sea eagle (<em>Haliaeetus leucogaster</em>). </p>
<p>Thus, it may seem like the odds are already stacked: what chance would a bird that eats fish as its main meal have against a bird that eats just about anything – alive or dead? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bald eagle over water" src="https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=457&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=457&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=457&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=574&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=574&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414507/original/file-20210804-24-hdkijd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=574&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bald eagles predominately prey on fish.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>A close match</h2>
<p>Well, they are in fact well matched in terms of potential fighting ability. </p>
<p>Both average about four to five kilograms, with almost identical wingspans of between 1.8 and 2.3 metres. Both have large, curved, strong beaks for tearing meat off the bones of their prey. </p>
<p>What opponents need to most be wary of, however, are the legs and talons. </p>
<p>Both species have strong feet with which to grab prey of the ground (or water) and carry it away to eat in peace. Neither have natural predators. It would indeed be a close match. </p>
<figure class="align-center ">
<img alt="The logos of the AFL's West Coast Eagles and the NFL's Philadelphia Eagles" src="https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=293&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=293&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414509/original/file-20210804-15-1go49r9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=293&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">AFL/NFL official logos</span></span>
</figcaption>
</figure>
<p>So, let’s say — hypothetically of course — that a wedge-tailed eagle and a bald eagle are in the same place at the same time, vying for the same prey. </p>
<p>It’s likely the bald eagle would be perched on a nearby clifftop, and the wedgie would be circling in the skies, high above. A poor, unassuming rodent (perhaps of unusual size, making it highly prized) is minding its own business on the ground below. </p>
<p>Both predators see the rodent as well as each other with their excellent vision — eagles generally have the best eyesight of all known vertebrates. A speedy downwards dive by both, up to 160 kilometres per hour, would signal the fight has commenced. </p>
<p>Before hitting the ground, the rodent, or each other, they’d flap their wings to slow down, revealing their legs and talons. These would reach out towards the opponent and, depending on where each bird grabs, might signify the end for the other. It would likely be quite the grapple and possibly even a trial of endurance. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=446&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=446&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=446&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=561&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=561&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414511/original/file-20210804-23-1v2d4c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=561&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wedge-tailed eagles have a wingspan of over two metres.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>The verdict?</h2>
<p>My money, however, is on the wedge-tailed eagle. </p>
<p>While wedge-tailed eagles are a similar size to bald eagles, they’re able to kill slightly bigger prey. Bald eagles tend to feed on fish and small mammals (as well as reptiles, and carrion to an extent), but they rarely target anything bigger than, say, a racoon or beaver. </p>
<p>While wedge-tails regularly eat similarly sized mammals such as rabbits, they will <a href="https://www.simoncherriman.com.au/wp-content/uploads/2019/02/HONOURS-THESIS.pdf">also attack</a> kangaroos, koalas and even goannas. </p>
<p>This might make them more accustomed to targeting diverse, large prey. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/o7_OWYrLVOU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bald eagle vs Donald Trump.</span></figcaption>
</figure>
<p>But the real tests that clinch my decision are odd encounters these birds face in the real world. </p>
<p>Recently, numbers of bald eagles have increased such that their range now overlaps with the common loon in North America, a diving waterbird with a sharp beak. And it appears that <a href="https://www.nationalgeographic.com/animals/article/why-loon-stabbed-bald-eagle-heart">loons are able to stab bald eagles</a> trying to obtain their young as prey, killing them. Canada 1: USA 0. </p>
<p>Not a great look for the majestic baldie. </p>
<p>Compare this to the wedge-tailed eagle, which is the only bird in the world known to <a href="https://www.smh.com.au/national/top-paraglider-attacked-by-eagles-20070202-gdpdxp.html">actively attack</a> paragliders and hang gliders , <a href="https://www.popsci.com/watch-australian-eagle-attack-drone/">as well as drones</a>. They do this because they likely see them as threats, and are attempting to defend their territory. </p>
<p>Therefore, in terms of motivation and sheer boldness when taking on an opponent, my bets are placed firmly in the talons of the wedgie.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/dofuOSR85t4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Who would win in a fight between a scorpion and a tarantula?</span></figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/who-would-win-in-a-fight-between-an-emu-and-a-cassowary-one-has-a-dagger-like-claw-the-other-explosive-agility-160540">Who would win in a fight between an emu and a cassowary? One has a dagger-like claw, the other explosive agility</a>
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<img src="https://counter.theconversation.com/content/164400/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dominique Potvin 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>It’s a clash that might rival Crocodile Dundee in New York City. While both iconic birds of prey are similarly sized, one is bolder and more ferocious.Dominique Potvin, Senior Lecturer in Animal Ecology, University of the Sunshine CoastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1609952021-05-20T19:58:19Z2021-05-20T19:58:19ZMouse plague: bromadiolone will obliterate mice, but it’ll poison eagles, snakes and owls, too<figure><img src="https://images.theconversation.com/files/401185/original/file-20210518-15-1z5t01.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5455%2C3289&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Masked owl (_Tyto novaehollandiae_), one of many birds of prey at great risk of secondary poisoning </span> <span class="attribution"><span class="source">Belinda Davis</span>, <span class="license">Author provided</span></span></figcaption></figure><p>It’s the smell that hits you first. The scent of urine and decomposing bodies. Then you notice other signs: scuttles and squeaks, small dead bodies leaking blood, tails sticking out of hubcaps. </p>
<p>If you’ve lived through a <a href="https://theconversation.com/no-one-ever-forgets-living-through-a-mouse-plague-the-dystopia-facing-australian-rural-communities-explained-by-an-expert-159339">mouse plague</a>, you’ve seen this, and smelled the stench of mice dying of poison baits.</p>
<p>As a desperate measure to help combat the mouse plague devastating rural communities across New South Wales, the state government yesterday <a href="https://www.canberratimes.com.au/story/7260799/nsw-secures-mice-killer-poison-for-farmers/?cs=14231">secured 5,000 litres of bromadiolone</a>. This is a bait that’s usually illegal to roll out at the proposed scale.</p>
<p>This is a bad idea. While bromadiolone effectively kills mice, it also travels up the food chain to poison predators who eat the mice, and other species. And these predators, from <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969721027443?via%3Dihub">wedge-tailed eagles</a> to goannas, are coming out in droves to feast on their abundant prey. </p>
<h2>When your prey is everywhere</h2>
<p>Animal plagues in Australia are fuelled by the “boom and bust” of rainfall. </p>
<p>We have natural, flood-driven population explosions of the native long-haired rat, with accompanying booms of letter-winged kites, their predator. We also have locust plagues when the conditions are right, leading to antechinus or mice plagues which eat the locusts. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1394622017920397329"}"></div></p>
<p><a href="https://theconversation.com/no-one-ever-forgets-living-through-a-mouse-plague-the-dystopia-facing-australian-rural-communities-explained-by-an-expert-159339">Since at least the late 1800s</a>, we’ve had terrible plagues of the introduced house mouse (<em>Mus musculus</em>). But rarely has it been this bad, with conditions currently seeming worse than the last plague in 2011, which caused over <a href="https://grdc.com.au/resources-and-publications/groundcover/ground-cover-issue-95-november-december-2011/plague-threat-pushes-mouse-bait-changes">A$200 million</a> in crop damage alone.</p>
<p>High numbers of birds of prey — nankeen kestrels, black-shouldered kites and barn owls — are often <a href="https://www.publish.csiro.au/mu/pdf/MU9820227">reported</a> feasting on plague mice. </p>
<p>Snakes, goannas, native carnivores such as quolls, and feral cats and foxes, also take advantage of the abundant food. Pets, especially cats and some dogs, are highly likely to consume mice under these conditions, too.</p>
<h2>Poisoning the food web</h2>
<p>Laying out poison baits is one way people try to end mouse infestations and plagues. So-called “anticoagulant rodenticides” are divided into first and second generations, based on when they were first synthesised and the differences in potency. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Wedge-tailed eagle" src="https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401782/original/file-20210520-13-4kg4l3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wedge-tailed eagles are among the predators that take advantage of the house mouse plague.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Second generation anticoagulant rodenticides have higher <a href="https://pubmed.ncbi.nlm.nih.gov/21481471/">toxicities</a> than first generation, and are lethal after a single feed. First generation rodenticides, on the other hand, require rodents to feed on them for consecutive days to be <a href="http://pesticideresearch.com/site/docs/bulletins/EPAComparisonRodenticideRisks.pdf">lethal</a>.</p>
<p>But mouse-eating predators are highly exposed to second generation rodenticides. For most animal species, the lethal doses of rodenticide aren’t yet known. </p>
<p>A <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969718312336?via%3Dihub">scientific review</a> from 2018 documented the poisoning of 31 bird, five mammal and one reptile species. Second generation aniticoaugulant rodenticides were implicated in the death of these animals.</p>
<p>Our <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969720317319?dgcid=coauthor">research</a> from 2020 found urban reptiles are highly exposed to second generation rodenticides, too. This includes mouse-eating snakes, called dugites, which had up to five different rodent poisons in them. </p>
<p>We also found poisons in frog-eating tiger snakes, and in omnivorous bobtail skinks which eat fruit, vegetation and snails. This is even more concerning because it shows how second generation rodenticides can saturate the entire foodweb, affecting everything from <a href="https://www.sciencedirect.com/science/article/pii/S0048969717321150">slugs</a> to <a href="https://link.springer.com/article/10.1007/s11356-018-1385-80">fish</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bobtail skink" src="https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401783/original/file-20210520-17-jzhuek.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">Bobtail skinks don’t eat poisoned mice, but they’ve still been found with poison in their systems.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Bromadiolone is particularly dangerous, even to humans</h2>
<p>The NSW government secured bromadiolone baits as part of its <a href="https://www.nsw.gov.au/media-releases/50-million-support-package-to-help-regional-communities-combat-mouse-plague">$50 million mouse plague support package</a> for regional communities. </p>
<p>Five thousand litres of the poison <a href="https://www.canberratimes.com.au/story/7260799/nsw-secures-mice-killer-poison-for-farmers/?cs=14231">can treat</a> around 95 tonnes of grain, and the government will provide it for free to primary producers once federal authorities approve its use. </p>
<p>Bromadiolone is usually restricted to use in and around buildings. But given the widespread impacts on wildlife, using bromadiolone at the proposed scale will do more harm than good. </p>
<p>Past research on bromadiolone has shown residues persist for up to 135 days in the carcasses of <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969708009030">voles</a> (another rodent species). In international studies, bromadiolone has been <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395208/">found</a> in the livers of a host of birds of prey, including a range of owl species, red kites, sparrowhawks and golden eagles. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Flock of chickens" src="https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401784/original/file-20210520-13-17tyigs.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">Humans can be exposed, too, by eating the eggs of chickens that ate the mice.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>And it’s not just a problem for wildlife, <a href="https://www.tandfonline.com/doi/full/10.1080/15563650600795966">humans</a> are also at risk of exposure. For example, we can get exposed from eating eggs from chickens that feed on poisoned mice, or more directly from eating other animals that may have ingested poisoned mice. </p>
<p>A <a href="https://journals.sagepub.com/doi/full/10.1177/1040638713501510">2013 study</a> looked at chicken eggs for human consumption, and detected bromadiolone in eggs between five and 14 days after the chicken ingested the poison. It’s not yet clear how many of these eggs we’d have to eat for us to get sick.</p>
<h2>So what are the alternatives?</h2>
<p>There are highly effective first generation rodenticides that provide viable solutions for managing mouse plagues. They may take a little longer to kill mice, but the upshot is they don’t stick around in the environment. A 2020 study found house mice in Perth <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0236234">didn’t have genetic resistance</a> to first generation rodenticides, which suggests they’re effectively lethal. </p>
<p>Another approach has been to use zinc phosphide, a poison which is unlikely to secondarily poison other animals that eat the poisoned mice. However, zinc phosphide is still extremely toxic and will kill sheep, cows, <a href="http://npic.orst.edu/factsheets/archive/znptech.html">pets and even humans</a> if directly eaten. </p>
<p>Rolling out double-strength zinc phosphide may be the lesser of the evils in causing secondary poisoning, but only if used very carefully.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1392315030012522497"}"></div></p>
<p>And another way to help control the mouse plague is to limit food resources for mice on farms. Farmers can minimise <a href="https://groundcover.grdc.com.au/weeds-pests-diseases/pests/harvest-clean-to-keep-mouse-numberslean">grain on ground</a>, and Australia should invest in research for <a href="https://extensionpubs.unl.edu/publication/9000016360405/rodent-proof-construction-structural">grain storage facilities</a> that are less permeable to mice.</p>
<p>Mouse plagues are a regular cycle in Australia. Natural predators not only help create healthy, natural ecosystems, but also they help with mouse control. Second generation rodenticides will only destroy and weaken the predator populations we need to help us combat the next plague.</p><img src="https://counter.theconversation.com/content/160995/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Davis is a member and former director of Birdlife Australia, a member of the Society for Conservation Biology and the Ecological Society of Australia.</span></em></p><p class="fine-print"><em><span>Bill Bateman receives funding from the Holsworth Wildlife Research Endowment. </span></em></p><p class="fine-print"><em><span>Damian Lettoof receives funding from the Holsworth Wildlife Research Endowment; and is a member of the Australian Society of Herpetologists, Ecological Society of Australia and Society of Environmental Toxicology and Chemistry.</span></em></p><p class="fine-print"><em><span>Maggie J. Watson is affiliated with Charles Sturt University and is a member of the board of the Ecological Society of Australia. </span></em></p><p class="fine-print"><em><span>Michael Lohr has previously received funding from funding from the Holsworth Foundation and Birdlife Australia. He is a member of with Birdlife Australia</span></em></p>The NSW government has secured an extremely toxic bait to try to end the mouse plague. But there are safer alternatives.Robert Davis, Senior Lecturer in Wildlife Ecology, Edith Cowan UniversityBill Bateman, Associate professor, Curtin UniversityDamian Lettoof, PhD Candidate, Curtin UniversityMaggie J. Watson, Lecturer in Ornithology, Ecology, Conservation and Parasitology, Charles Sturt UniversityMichael Lohr, Adjunct Lecturer, Edith Cowan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1227962019-09-02T15:15:11Z2019-09-02T15:15:11ZBarn owls reflect moonlight in order to stun their prey<figure><img src="https://images.theconversation.com/files/290516/original/file-20190902-175714-8g3goq.jpg?ixlib=rb-1.1.0&rect=0%2C11%2C7360%2C4891&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/barn-owl-flight-hunting-black-background-1082537198?src=-1-8">FJAH/Shutterstock</a></span></figcaption></figure><p>Ecosystems that are bathed in light during the day change profoundly at night. As the sun fades from the land, nocturnal life emerges, with the barn owl (<em>Tyto alba</em>) among them. Barn owls are iconic nocturnal birds of prey that are found all over the world, often near towns and villages. Although a familiar species to many, there is still much we don’t know about them.</p>
<p>One peculiarity is the difference in plumage colour between different barn owls. Why is it that some have undersides that are completely white while others are dark red? This puzzled scientists for a long time, but finally, we have an answer.</p>
<p>The light conditions in sunlit environments determine how the colour traits of animals evolve, as the composition and quantity of light affects how well an animal is seen by predators or competitors. The stripes of a tiger, for instance, allow this large cat to easily disappear in the dense Indian forest, where the shifting canopy <a href="https://academic.oup.com/beheco/article/28/2/373/2674187">splits light into lines</a>. But how light conditions affect the colouration of nocturnal species is less well understood. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290513/original/file-20190902-175710-bn2eha.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">White-chested and red-chested barn owls both hunt rodents at night – but their success depends on the moonlight.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Kerkuil_licht_en_donker.jpg">Kerkuil/Wikipedia</a>, <a class="license" href="http://artlibre.org/licence/lal/en">FAL</a></span>
</figcaption>
</figure>
<p>The light at night changes according to the lunar cycle. Go out on a night with a new moon in a rural area and you’ll need a torch to see. Do the same on a night with a full moon and you’ll probably have enough light to see without one. How do barn owls deal with these radical changes in light levels from night to night?</p>
<p>We thought they would have a harder time hunting the rodents they need to feed their offspring on moonlit nights. In the bright moonlight, owls should be more easily spotted by prey such as mice. If this was true, hunting on moonlit nights would be even trickier for white owls than for red owls, simply because white is more reflective and therefore more visible in the moonlight than dark red plumage. As it turns out, we couldn’t have been more wrong.</p>
<h2>Blinded by the moonlight</h2>
<p>We’ve been following a Swiss population of barn owls for more than 20 years, monitoring their hunting behaviour with cameras and GPS trackers and recording when they breed each year and how their offspring develop in the nest. By studying this rich data set, we found that barn owls do indeed have a harder time on moonlit nights. They’re less successful hunters and bring less prey to the nest and as they receive less food, their offspring don’t gain as much weight and the youngest have lower chances of surviving and fledging. This was true for red barn owls, but not, surprisingly, for white barn owls. On the contrary, white barn owls seemed to be doing just as well during full moon nights as when there was no moon.</p>
<p>Perplexed, we decided to look at the problem from the perspective of the rodents that barn owls hunt every night. Our experiment investigated how common voles – <a href="https://www.woodlandtrust.org.uk/blog/2019/01/what-do-owls-eat/">the main prey of barn owls</a> – see and react to white and red owls under full and new moon light conditions. </p>
<p><a href="https://www.nature.com/articles/s41559-019-0967-2">We found</a> that prey detected owls more easily on full moon nights, regardless of what colour they were. We knew when the rodents had detected an owl because they froze. Staying immobile is a common prey behaviour, as they aim to stay undetected and allow the risk to pass. Curiously, on full moon nights and only when facing a white owl instead of a red one, rodents stayed frozen for longer.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290489/original/file-20190902-175682-1kshq87.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">Researchers huddle in the dark to study barn owls mid-hunt.</span>
<span class="attribution"><span class="source">Jérémy Bierer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We think voles behave that way when encountering a white owl because they’re scared by bright light reflected from the white plumage. This fear is well ingrained within rodents – medical researchers expose rodents to bright light to measure their fear response and test drugs on them which are designed to treat anxiety. The white plumage of barn owls exploits this fear by reflecting moonlight. This may explain why white plumage – a very rare trait in nocturnal animals – evolved in this species.</p>
<p>This discovery should remind people how important it is to better understand and preserve nocturnal wildlife and the environments they live in. Minimising light pollution and letting the night be as dark as the moon dictates could benefit beautiful barn owls.</p><img src="https://counter.theconversation.com/content/122796/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Almut Kelber receives funding from Lund University, Sweden, the K & A Wallemberg Foundation, Stockholm and the Swedish Research council.. </span></em></p><p class="fine-print"><em><span>Alexandre Roulin and Luis Martín San José García 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>Scientists have discovered how the wise old barn owl is so good at catching rodents.Almut Kelber, Professor of Biology, Lund UniversityAlexandre Roulin, Professeur, Chercheur Ornitologue, Université de LausanneLuis Martín San José García, Postdoctoral Researcher in Evolutionary Biology, Université de LausanneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1064802018-11-07T14:47:14Z2018-11-07T14:47:14ZWind turbines aren’t quite ‘apex predators’, but the truth is far more interesting<figure><img src="https://images.theconversation.com/files/244339/original/file-20181107-74772-17iqpdp.jpg?ixlib=rb-1.1.0&rect=5%2C436%2C3980%2C2306&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Blue Planet Studio / shutterstock</span></span></figcaption></figure><p>Wind turbines are, it appears, everywhere. Even if you can’t see some on the horizon on your way into work every day, it is hard to miss the continual news coverage of new developments. Clearly, efforts to move away from fossil fuels are – at least in part – working, and from the perspective of combating climate change, this must surely be a good thing.</p>
<p>However, much of the news coverage of turbines highlights negatives such as a perceived degradation of the landscape, or their impacts on wildlife. There is good cause for concern in this regard, particularly with respect to wildlife. </p>
<p>Reams of published scientific papers show that birds and bats can be killed (sometimes in relatively large numbers) by colliding with the spinning blades. Clearly, where turbines are poorly placed or where rare or vulnerable species are affected, this is a problem. Images of <a href="https://www.telegraph.co.uk/news/earth/earthnews/8385561/Why-birds-crash-into-wind-turbines.html">dead birds of prey</a> or <a href="https://www.bbc.co.uk/news/uk-scotland-highlands-islands-23082846">rare vagrant birds</a> under wind turbines are easily turned into emotive and sensational news stories, and are terrible PR for the wind industry.</p>
<p>At first glance, a new study published in <a href="https://www.nature.com/articles/s41559-018-0707-z">Nature Ecology & Evolution</a> appears to add to the evidence of widespread lethal effects. The authors, a team based at the Indian Institute of Science and led by Maria Thaker, make the attention-grabbing observation that the effects of wind turbines are “akin to adding an apex predator to natural communities”. Apex predators are animals right at the top of their food chains, like killer whales or tigers. Adding an “apex predator” surely means that these man-made metal mincing-machines kill off birds and bats in large numbers, right? </p>
<h2>Creatures great and small</h2>
<p>While it certainly is true that collision with turbines can cause direct mortality, what the new research actually shows is far more interesting and complex than this. The result of many years of data collection, the work shows that through the (direct or indirect) effects on birds of prey, wind turbines can have broader and more subtle effects on the wider ecosystem – including on some unexpected species.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/244345/original/file-20181107-74787-1f3bhwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The superb large fan throated lizard has only been classed as a separate species since 2016.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Superb_large_fan-throated_lizard_Sarada_superba_by_Krishna_Khan.jpg">Krishna Khan</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Specifically, they looked at a lizard that lives only in the Western Ghats mountains of India, the <a href="http://www.contributionstozoology.nl/cgi/t/text/get-pdf?c=ctz;idno=8501a04">superb fan-throated lizard</a> (<em>Sarada superba</em>). They found that the number of lizards was considerably higher in areas with turbines installed compared to otherwise similar areas without turbines. </p>
<p>In areas with turbines, they also found fewer birds of prey such as buzzards and kites (the lizards’ main predators), and a lower frequency of attacks on lizards. Putting the two together, the authors propose that the presence of turbines is associated with lower predator activity, and thus higher prey numbers.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/244343/original/file-20181107-74783-ndlz5a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Western Ghats run parallel to the west coast of India for 1,600km.</span>
<span class="attribution"><span class="source">Vihang Ghalsasi / Shutterstock</span></span>
</figcaption>
</figure>
<p>In some ways, it may indeed seem as if wind turbines act similarly to the introduction of an “apex predator” into the food chain: by reducing the number and activity of intermediate predators such as birds of prey, predation pressure on smaller animals may be reduced. However, it is of course important to stress that almost all biological predators are, in the end, limited by the availability of prey. By contrast, turbines are not limited in this way and will continue to be present regardless of whether their “prey” goes locally extinct. </p>
<p>Perhaps more important is the non-lethal effects on the wider ecosystem that is highlighted by Thaker and colleagues. By reducing predation or reducing the activity of predators, the physiology, behaviour and population density of prey populations can be changed in unpredictable and subtle ways.</p>
<h2>Looking beyond the collision casualties</h2>
<p>What this work really highlights is that wind farms can have effects that are indirect or not immediately visible. This poses a huge challenge for impact assessments and survey work. Perhaps understandably, many assessments of wind turbines focus on vulnerable species, which tend to be the birds and bats most at risk of direct collision. Similarly, where carried out, post-construction monitoring often focuses on collision casualties. These are things that can be directly measured or counted, over clearly defined periods. </p>
<p>By contrast, assessing the longer-term effects on indirectly impacted species such as lizards takes a lot more time and money. Unfortunately, this luxury is typically not available for commercial impact assessment studies. What is more, it is likely to be significantly harder to convince regulators that impact assessments should be broadened to consider wider ecosystems, particularly where these cannot be immediately seen or counted as dead animals.</p>
<p>At least in the UK, there is some evidence that consideration of such “synergistic” effects of developments is now <a href="https://www.cieem.net/ecia-guidelines-terrestrial-">increasingly expected in impact assessments</a>. While this is encouraging, more work along the lines of study by Thaker and colleagues is needed to build up a better understanding of the extent and importance of similar effects in different areas. From a pragmatic perspective, it may well be that in the future impact assessments will move away from focusing on direct collision mortality and towards more targeted and in-depth assessments of “downstream” ecological impacts.</p><img src="https://counter.theconversation.com/content/106480/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeroen Minderman 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>A new study claims that wind turbines kill enough birds of prey that they are effectively an ‘apex predator’.Jeroen Minderman, Research Fellow, Biological and Environmental Sciences, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/544082016-02-10T04:37:31Z2016-02-10T04:37:31ZEagles and agriculture: not a zero sum game<figure><img src="https://images.theconversation.com/files/110763/original/image-20160209-12574-ytvm0l.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">Megan Murgatroyd</span></span></figcaption></figure><p>Conservationists worry about the impact of agricultural development on Africa’s biodiversity. But a recent study shows it isn’t necessarily all doom and gloom. Some species, like eagles, can coexist successfully with agricultural development.</p>
<p>As the world’s human population continues to increase, so too does our demand for <a href="http://www.un.org/press/en/2009/gaef3242.doc.htm">food</a>. One of the biggest challenges is how to meet this demand and not damage the environment.</p>
<p>Based on experiences from Europe and north America, as natural land is converted to farming, biodiversity <a href="http://www.grida.no/publications/rr/food-crisis/page/3569.aspx">suffers</a>. Much research has focused on the negative impact this can have on <a href="http://rspb.royalsocietypublishing.org/content/268/1462/25">birds</a>.</p>
<p>Agricultural development is on the rise in <a href="http://link.springer.com/article/10.1023/A:1010039224868">Africa</a>. And the world is increasingly looking to it to <a href="http://www.un.org/en/africa/osaa/pdf/pubs/2013africanagricultures.pdf">supply more food</a>. But the impact this will have on the continent’s biodiversity remains unknown and under-explored compared with more developed regions.</p>
<p>Our study suggests that some birds of prey can adapt to and even benefit from human-altered landscapes. Case studies like these support the idea that agricultural areas can play an important role in conservation.</p>
<p>Birds of prey are often promoted as useful indicators of the health of the <a href="http://www.raptorresearchfoundation.org/conservation">environment</a>. For example, it was the decline of the <a href="http://www.rspb.org.uk/discoverandenjoynature/discoverandlearn/birdguide/name/p/peregrine/population.aspx">peregrine falcon</a> that was instrumental in revealing the negative impact of the pesticide DDT in the food chain in the 1960s. </p>
<p>Some birds of prey have also been useful to show how agricultural intensification is harming the environment. As their habitat and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919x.2004.00314.x/abstract">prey</a> is depleted, their numbers can <a href="http://www.sciencedirect.com/science/article/pii/S0006320702002513">shrink</a>.</p>
<h2>The case of the Verreaux’s Eagle</h2>
<p>The Verreaux’s Eagle, also known previously as the Black Eagle, holds an iconic presence in mountainous and rocky habitats. It is <a href="http://www.birdlife.org/datazone/speciesfactsheet.php?id=3539">distributed</a> across much of sub-Saharan Africa. The species is famous among ornithologists for having an extremely specialised diet. Previous studies have shown that around 90% often consists of a single prey type - the <a href="http://www.awf.org/wildlife-conservation/hyrax">hyrax</a>, a small mammal closely related to the elephant.</p>
<p><a href="http://www.theguardian.com/news/datablog/2012/dec/06/wild-bird-population-declines-specialist-species-suffer">Specialist species</a> are often thought to be among the most vulnerable and least able to cope with <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1890/080216/abstract">environmental change</a>. This is what makes them one of the most useful indicators of environmental change.</p>
<p>This species has shown recent <a href="http://sabap2.adu.org.za">declines</a> in South Africa. As a result, its regional conservation status has recently been elevated to vulnerable. One possible explanation for the decline is agricultural development.</p>
<p>Our <a href="http://www.aoucospubs.org/doi/abs/10.1650/CONDOR-15-142.1">study</a> explored this. We compared the breeding performance of two populations in the Western Cape province of South Africa. One population living in the pristine Cederberg Mountains, the second in the adjacent Sandveld region. The Sandveld region is lower lying and has been extensively <a href="http://www.conservation.org/global/ci_south_africa/our-initiatives/food-security-land-reform/greenchoice/Pages/Potatoes.aspx">developed</a> for agriculture, particularly potato farming.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=412&fit=crop&dpr=1 600w, https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=412&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=412&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=518&fit=crop&dpr=1 754w, https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=518&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/110764/original/image-20160209-12606-sy7cag.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=518&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A mixed lunch variety of prey species on a nest in the Sandveld.</span>
<span class="attribution"><span class="source">Megan Murgatroyd</span></span>
</figcaption>
</figure>
<p>We expected that a specialist species like the Verreaux’s Eagle would be negatively affected by this agricultural development. We thought that it would breed less successfully than its neighbours in a natural and largely protected habitat.</p>
<p>Much to our surprise we found the opposite. Eagles in the agricultural area produced 2.7 times more young than pairs breeding in the pristine habitat. </p>
<p>The breeding performance in the agricultural area was actually the best ever recorded for this species. Conversely, the population in the Cederberg has one of the lowest breeding performances ever recorded for the species. We modelled the likely population trends of these two populations and our results suggested that the Cederberg would not sustain itself into the future, unless birds come in from elsewhere.</p>
<p>Research on the European <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1469-1795.2011.00449.x/abstract">Marsh Harrier</a> has produced the same findings. With suitable breeding habitat and the availability of small mammal prey it thrives in intensive agricultural habitats. </p>
<h2>Why the counter-intuitive outcomes</h2>
<p>We explored whether these difference could be due to better or more varied food supplies in the agricultural land. We found some support for this idea. Within the Cederberg, the hyrax made up 98% of the eagles’ diet. But within the agricultural Sandveld region, their diet was more varied and included tortoises and mole-rats. </p>
<p>So it seems that this specialised species isn’t negatively affected when switching away from its usual prey. But because there isn’t enough information on diet from this population prior to agricultural development, we do not know whether the dietary changes are due to agricultural development, or whether this population has always had a more varied diet.</p>
<p>Another possibility for the greater breeding productivity in the Sandveld is a laid-back lifestyle. Different land features can drive contrasting uplift availability. In mountainous terrain, air movement over ridges creates uplift, which can be harnessed by eagles for soaring flight. In flatter terrain, like the Sandveld, eagles rely on gaining altitude by thermal soaring, which is achieved by circling in upwards moving pockets of warm air. So it might just be that energy consumed in flight is different between the two populations.</p>
<p>Caution is needed when exploring how general these patterns are. It is likely even for the Verreaux’s eagle that there will be a threshold level above which agricultural development will start having a negative <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7348.2005.040078.x/abstract">impact</a>. Farmland consisting of a <a href="http://www.sciencedirect.com/science/article/pii/S0006320709001062">mixture</a> of natural and non-natural habitats seems to favour this species. It’s uncertain whether it would do so well if farming intensified.</p>
<p>The results of our study will hopefully contribute to the debate on what the best way forward should be to protect biodiversity while at the same time allowing agricultural development. There are a a number of possible options. These include land sharing, mixes of natural and farmed habitats or separate farmed and protected <a href="http://science.sciencemag.org/content/333/6047/1289.short">habitat</a>.</p><img src="https://counter.theconversation.com/content/54408/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Megan Murgatroyd received funding from the National Research Foundation, the National Birds of Prey Trust and the Cape Leopard Trust. </span></em></p><p class="fine-print"><em><span>Arjun Amar receives funding from the National Research Foundation (South Africa). </span></em></p><p class="fine-print"><em><span>Les Underhill receives funding from the National Research Foundation and the University of Cape Town Research Committee. </span></em></p>Biodiversity is known to suffer in human-altered agricultural areas. But the Verreaux Eagle is an exception and has seen its numbers increase in agricultural land..Megan Murgatroyd, PhD candidate, University of Cape TownArjun Amar, Senior Lecturer, Percy FitzPatrick Institute of African Ornithology, University of Cape TownLes Underhill, Professor, Biodiversity Informatics, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/299252014-08-11T05:15:30Z2014-08-11T05:15:30ZRadical steps required to save birds of prey from illegal killing<figure><img src="https://images.theconversation.com/files/55412/original/vtf65xk2-1406793365.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hen harrier causing trouble.</span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Hen_Harrier.jpg">Andreas Trepte</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Across the open <a href="http://www.moorlandassociation.org/heather_moorland.asp">heather moors</a> of upland Britain, last-minute preparations are being put in place for the start of the <a href="http://www.gwct.org.uk/research/species/birds/red-grouse/">red grouse shooting season</a> on August 12. On average about <a href="http://www.moorlandassociation.org/economics3.asp">200,000 grouse are shot every year</a> in England and Wales. Yet the management that makes such large numbers of grouse available for the guns in autumn is becoming increasingly contentious. The reason is that there is a growing and convincing body of evidence that suggests that birds of prey, or raptors, are being illegally killed by those who manage grouse stocks.</p>
<p>These accusations of <a href="http://www.rspb.org.uk/Images/illegalkillingbirdsofprey2012_tcm9-371269.pdf">illegal killings</a> of birds such as harriers, falcons and eagles has given rise to a clash between those on both sides of the debate. While the main conservation and game shooting organisations claim to be keen to see an end to this illegal activity, they favour different approaches.</p>
<p>The conservationists tend to back the strengthening and enforcement of policy. For example, the <a href="http://www.rspb.org.uk/">RSPB</a> demands that grouse shooting be licensed, so that a licence may be revoked should illegal activity be detected. Mark Avery, the former head of conservation science at the RSPB, has gone further and demanded that <a href="http://markavery.info/category/e-petition-to-ban-driven-grouse-shooting/">grouse shooting be banned</a>. There is a day of protest set for August 10, and Marks & Spencer recently found themselves in the protesters’ sights for their plans to <a href="http://www.bbc.co.uk/news/business-28483764">sell grouse in their stores</a>.</p>
<p>In contrast, supporters of <a href="http://www.countrysportscotland.com/shooting/red-grouse/">red grouse shooting</a> claim that the land management associated with it has benefited a range of species, as well as bringing income and jobs into remote rural areas. They wish to see some form of legal management of birds of prey. Feelings run high; many question why it seems to be a taboo to discuss the management of raptors and why the desire to increase the number of these birds should come before jobs and communities.</p>
<p>The <a href="https://www.rspb.org.uk/wildlife/birdguide/name/h/henharrier/">hen harrier</a> finds itself at the epicentre of this conflict. The species has virtually disappeared as a breeding bird on intensively managed grouse moors – killed because of its efficient hunting of grouse. One of the features of the harrier is that it is not particularly territorial, so on some grouse moors it can breed at levels that lead to significant financial losses for those involved.</p>
<p>So what is the best way of resolving this problem? A shooting ban would certainly lead to a change in how large swathes of our uplands are managed. However, the costs and benefits of this change for the communities, predators and other species would depend on what it is replaced with. Such an approach would also inevitably anger many of those involved in land management and possibly damage the long-term relationships between hunters and conservation organisations. </p>
<p>Could the management of harriers provide a solution? A forthcoming population modelling study due to be published in the <a href="http://www.journalofappliedecology.org/view/0/index.html">Journal of Applied Ecology</a> explored one approach. The study highlighted the densities at which harriers could co-exist with driven grouse shooting through a quota or brood management scheme. </p>
<p>The idea is simple: once numbers go beyond some agreed level the chicks would be moved into captivity until ready to fly, when they would be released to rejoin the wild population. It may sound an unusual way of managing a wild species, but there is a precedent for it. In continental Europe, harriers breed in agricultural crops and are often killed if they aren’t flying before the combines harvest the crop. Instead, harrier chicks are taken into captivity before harvesting and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2000.tb07679.x/abstract">subsequently released</a>. This approach could allow the co-existence of harriers and grouse without recourse to illegal killing, but it would need to be tested in the field. </p>
<p>The problem is that the conservation movement are nervous because of the precedent this approach sets for active management of birds of prey – even if it ultimately led to more harriers. They argue that any discussion around techniques that would affect birds of prey should only take place once harriers are allowed to breed freely on grouse moors. Unsurprisingly, grouse managers will only trial such a scheme if there is an agreed quota, and an exit strategy that they can work towards. </p>
<p>We are at a crossroads, but it is not yet clear which way we are going to go: enforcement or management? While science has provided evidence, in the end the decision will – as is so often the way – depend as much on political, moral, social and economic arguments as it does on science.</p><img src="https://counter.theconversation.com/content/29925/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steve Redpath has received funding from UK Research Councils, the European Union as well as government agencies and NGOs</span></em></p>Across the open heather moors of upland Britain, last-minute preparations are being put in place for the start of the red grouse shooting season on August 12. On average about 200,000 grouse are shot every…Steve Redpath, Chair in Conservation Science, Aberdeen University., University of AberdeenLicensed as Creative Commons – attribution, no derivatives.