tag:theconversation.com,2011:/ca/topics/darwins-finches-10302/articlesDarwin's finches – The Conversation2021-01-15T11:15:13Ztag:theconversation.com,2011:article/1530102021-01-15T11:15:13Z2021-01-15T11:15:13ZVampire finches: how little birds in the Galápagos evolved to drink blood<figure><img src="https://images.theconversation.com/files/378725/original/file-20210114-16-vfuqom.jpg?ixlib=rb-1.1.0&rect=898%2C223%2C1034%2C773&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jaime Chaves</span>, <span class="license">Author provided</span></span></figcaption></figure><p>For most people, the word “vampire” brings to mind Dracula or perhaps slayers such as Blade or Buffy; or maybe even the vampire bats of South America. Few will think of a small and rather lovely bird – the finch.</p>
<p>But there are indeed “vampire finches” that feast on the blood of much larger birds, and they were introduced to the world in a fantastic segment of <a href="https://www.bbc.co.uk/iplayer/episode/p08xc2v8/a-perfect-planet-series-1-1-volcano">Perfect Planet</a>, the new series narrated by <a href="https://theconversation.com/why-david-attenborough-cannot-be-replaced-152193">David Attenborough</a> for the BBC. For us, these finches needed no introduction as we have studied them closely. </p>
<p>These birds are found on the Galápagos Islands, a volcanic archipelago located about 1,000 km (600 miles) off the coast of Ecuador. The islands are a biodiversity hotspot in part because of their isolation. Organisms that somehow make it to the Galápagos must adapt to the harsh conditions or go extinct.</p>
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<p>One such group of organisms is the Darwin’s finches. Named after the naturalist Charles Darwin, who collected examples on his famous voyage aboard the HMS Beagle, this group of finches consists of several species that have <a href="https://pubmed.ncbi.nlm.nih.gov/25686609/">evolved from a common ancestor</a>. Each species has evolved a different bill size and shape which allows it to exploit different food items. For example, the cactus finch has a long thin bill that allows it to consume the nectar from of cactus flowers. Some species have bills that are better at crushing seeds, while others are better at consuming insects or plants.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Drawings of finches." src="https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=453&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=453&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=453&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=569&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=569&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378727/original/file-20210114-21-sh2sj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=569&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Different bills for different food.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Darwin%27s_finches_by_Gould.jpg">Darwin's finches, drawn by the ornithologist John Gould in 1845</a></span>
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<p>It makes sense that different species of finches evolved to feed on different types of food items on the Galápagos, but where did blood feeding come from? </p>
<h2>How blood sucking evolved</h2>
<p>The vampire finches are found only on Wolf and Darwin, the two northernmost islands of the archipelago and remote even by Galápagos standards. Both islands are tiny, each less than a square mile, and are separated from the larger islands by 100 miles of open ocean. Fresh water is extremely rare and some food can disappear entirely during the dry season. </p>
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<a href="https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large bird looks out to sea." src="https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378729/original/file-20210114-22-rc3pfb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Target: a Nazca booby.</span>
<span class="attribution"><span class="source">Kiyoko Gotanda</span>, <span class="license">Author provided</span></span>
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<p>At some point in the last <a href="https://bioone.org/journals/the-auk/volume-135/issue-3/AUK-17-215.1/Biogeographic-origins-of-Darwins-finches-Thraupidae-Coerebinae/10.1642/AUK-17-215.1.full">half million years</a> – recent in evolutionary terms – finches arrived on Wolf and Darwin and began to co-exist with large seabirds which nest on the islands, such as red-footed and Nazca boobies. Over time, it seems the finches likely evolved to eat <a href="https://www.biodiversitylibrary.org/item/277112#page/247/mode/1up">parasites found in the feathers and on the skin of the boobies</a>. This was “mutualism” in action: the boobies benefited from parasite removal, and the finches benefited by having an alternative to their usual diet of nectar, seeds and insects which can disappear during the dry season. </p>
<p>Eventually however, the removal of parasites led to open skin lesions on the boobies, allowing the finches to <a href="http://aquaticcommons.org/9976/1/NG_38_1983_Koster_Twelve_days.pdf">consume blood</a>. The finches even learned to pierce skin at the base of young feathers to access the blood directly, no longer needing the insect parasites anymore. Thus, the finches capitalised on an alternative food resource, blood from the boobies, and earned themselves the nickname “vampire finches”.</p>
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<a href="https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small bird sits on bigger bird, eats blood" src="https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=522&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=522&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=522&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=656&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=656&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378732/original/file-20210114-14-1se6yry.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=656&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 vampire finch feeds from an open wound on a Nazca booby.</span>
<span class="attribution"><span class="source">Jaime Chaves</span>, <span class="license">Author provided</span></span>
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<p>It’s hard to know exactly how much of the finch’s diet is booby blood, but our unpublished data suggests it’s about a tenth. Natural selection appears to have fine-tuned the vampire finch beak for skin-piercing and blood-sucking, as the birds have evolved particularly <a href="https://www.jstor.org/stable/2408396?seq=1">long and pointy beaks</a> compared to non-blood-feeding populations on other islands. And once a blood-feeder pierces the skin, it still needs a way to consume and digest the blood. When we studied the microbes found in the guts of these vampire finches in search of adaptations we found a <a href="https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-018-0555-8">very different microbiome</a> from any other species of Darwin’s finches, presumably caused by the blood diet.</p>
<h2>What it’s like to see in person</h2>
<p>Two of us, Daniel and Jaime, went to Darwin and Wolf along with professor <a href="http://www.sas.rochester.edu/bio/people/faculty/uy_albert/index.html">Albert Uy</a> to study these fascinating finches on islands that are very rarely visited, even by researchers. Getting there was extremely challenging as there are no beaches for landing a boat. We had to approach the cliffs in a small dinghy and then wait for a brief gap in the waves before jumping onto sharp, black lava rocks. But this isolation means the vampire finches are plentiful, and the dense breeding colonies of boobies made it easy to envision how this strange blood sucking behaviour could have evolved. </p>
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<a href="https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bird with exposed gullet; a small bird with bloody bill" src="https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378726/original/file-20210114-20-13ttifi.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">Left: a vampire finch crop (food store in the throat) full of blood. Right: A vampire finch with bloody bill.</span>
<span class="attribution"><span class="source">Daniel Baldassarre</span>, <span class="license">Author provided</span></span>
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<p>The boobies are incredibly vulnerable when tending to nests and chicks, as they are reluctant to abandon them, even temporarily. We observed scores of vampire finches clamouring all over the backs, tails, and wings of boobies, opening up substantial wounds with their sharp beaks, and drinking their fill of blood. Interestingly, the finches seem to act like a true parasite, inflicting enough damage to secure a meal without excessively harming the host. </p>
<p>For the boobies, the whole experience really is very similar to a human being attacked by mosquitos. Though they can tolerate the finches, the small bloodsuckers are a nuisance that the boobies do try to get rid of. And when it all gets too much, they can be forced to fly away.</p>
<p>And who can blame them? When we captured finches to collect samples, and found gullets full of blood, and beaks stained red. It was evident that the little vampires were not merely lapping up a few drops of blood.</p><img src="https://counter.theconversation.com/content/153010/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kiyoko Gotanda received funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), Le Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT), the British Ornithologists' Union Research Grant, and Christ's College, Clare Hall, and Newnham College at the University of Cambridge</span></em></p><p class="fine-print"><em><span>Daniel Baldassarre and Jaime Chaves 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>Finches have evolved to feed off blood from red-footed and Nazca boobies – and we’ve seen it first-hand.Kiyoko Gotanda, Postdoctoral Research Fellow, Université de Sherbrooke and, University of CambridgeDaniel Baldassarre, Assistant Professor of Zoology, State University of New York OswegoJaime Chaves, Assistant Professor, Ecology and Evolution, San Francisco State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1185862019-06-12T06:09:58Z2019-06-12T06:09:58ZA parasite attack on Darwin’s finches means they’re losing their lovesong<figure><img src="https://images.theconversation.com/files/278820/original/file-20190611-32351-1hoo5hb.jpg?ixlib=rb-1.1.0&rect=29%2C196%2C2710%2C1683&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Small Tree Finch from the Galápagos Islands with an enlarged nostril caused by a parasite.</span> <span class="attribution"><span class="source">Katharina J Peters</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A parasite known to infect beaks in some iconic Darwin finches on the Galapagos Islands is changing the mating song of male birds.</p>
<p>Our research, <a href="http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2019.0461" title="Introduced parasite changes host phenotype, mating signal and hybridisation risk: Philornis downsi effects on Darwin’s finch song">published today in Proceedings of the Royal Society B</a>, reveals how the parasite deforms the beak. This has the effect of weakening the male bird’s mating call, and making it no longer clearly distinguishable from that of other closely related species.</p>
<p>A changed song can have an important effect on the male finch’s ability to find a mate. </p>
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Read more:
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<p>It’s another factor that could contribute to declining numbers of these already threatened birds on the Pacific archipelago, about 1,000km off the coast of South America.</p>
<h2>A family song to impress</h2>
<p>A male finch learns the mating song from his father, and produces the same song for the <a href="https://www.pnas.org/content/107/47/20156/tab-article-info" title="Songs of Darwin's finches diverge when a new species enters the community">rest of his life</a>.</p>
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<p>It’s a simple tune consisting of one syllable repeated 3 to 15 times, depending on what species of finch he belongs to. Larger-bodied finch species produce a slower song with few syllable repeats, and smaller-bodied finch species produce faster song with <a href="https://www.cambridge.org/core/journals/bird-conservation-international/article/avian-population-trends-in-scalesia-forest-on-floreana-island-20042013-acoustical-surveys-cannot-detect-hybrids-of-darwins-tree-finches-camarhynchus-spp/7FE5D763A26BC9C0398398DE336CB778">many syllable repeats</a>.</p>
<p>Whatever species of finch you belong to, hitting the high notes is important – because females prefer males who can produce such vocally challenging songs. </p>
<p>In the case of the <a href="https://link.springer.com/article/10.1007/s10531-009-9740-1">Medium Tree Finch</a> (<em>Camarhynchus pauper</em>), a critically endangered species that only occurs on Floreana Island of the Galapagos Islands, its species-typical song has a bright resonance that rings across the forest canopy.</p>
<p><audio preload="metadata" controls="controls" data-duration="2" data-image="" data-title="Medium Tree Finch" data-size="36361" data-source="" data-source-url="" data-license="Author provided" data-license-url="">
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Medium Tree Finch.
<span class="attribution"><span class="license">Author provided</span><span class="download"><span>35.5 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1607/medium-tree-finch-with-normal-naris-size.mp3">(download)</a></span></span>
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<p>An accomplished male singer that can hit the high notes is quickly swooped up by a female looking to pair with a proficient singer. </p>
<h2>The ‘Vampire’ parasite</h2>
<p>The Vampire Fly – a <a href="https://twitter.com/CStenoien/status/1110602027275571200">suggested name</a> for the parasite <em>Philornis downsi</em> given its blood feeding habits from dusk until dawn – was <a href="https://onlinelibrary.wiley.com/doi/full/10.1046/j.1474-919X.2002.00076.x" title="Philornis downsi– a recently discovered parasite on the Galápagos archipelago – a threat for Darwin's finches?">first discovered in a Darwin’s finch nest in 1997</a>.</p>
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<a href="https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.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>
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<span class="caption">The parasitic <em>Philornis</em> larvae in a finch nest.</span>
<span class="attribution"><span class="source">Sonia Kleindorfer</span>, <span class="license">Author provided</span></span>
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<p>Since then, the devastating impacts of its larval feeding habits on nestling birds have been <a href="https://www.cambridge.org/core/journals/parasitology/article/lifecycle-of-philornis-downsi-diptera-muscidae-parasitizing-darwins-finches-and-its-impacts-on-nestling-survival/597D469905598A7105BBE59990009B32">coming to light</a>. The adult fly is vegetarian, but the females lay their eggs into bird nests and their <a href="https://bmczool.biomedcentral.com/articles/10.1186/s40850-016-0003-9" title="Host-parasite ecology, behavior and genetics: a review of the introduced fly parasite Philornis downsi and its Darwin’s finch hosts">larvae feed on nestling bird beaks from the inside out</a>. </p>
<p>Many Darwin’s finch species now have beaks with massively enlarged nostrils because of damage the feeding fly larvae have caused <a href="https://www.sciencedirect.com/science/article/pii/S2351989416300336?via%3Dihub" title="Naris deformation in Darwin’s finches: Experimental and historical evidence for a post-1960s arrival of the parasite Philornis downsi">during the nestling stage</a>. We discovered that a changed beak apparatus measurably affects the song of Darwin’s tree finches with consequences for pairing success. </p>
<p>A Medium Tree Finch male with extremely enlarged nostrils is unable to hit the high notes.</p>
<p><audio preload="metadata" controls="controls" data-duration="2" data-image="" data-title="Medium Tree Finch with enlarged nostrils" data-size="33017" data-source="" data-source-url="" data-license="Author provided" data-license-url="">
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Medium Tree Finch with enlarged nostrils.
<span class="attribution"><span class="license">Author provided</span><span class="download"><span>32.2 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1608/medium-tree-finch-with-parasite-induced-naris-enlargement.mp3">(download)</a></span></span>
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<p>We found the same pattern in Small Tree Finches (<em>C. parvulus</em>) with enlarged nostrils. </p>
<p>Male finches that produce song with a narrower frequency bandwidth, because their song has a lower maximum frequency, have poor quality song. These males are less likely to be chosen by females, a pattern we documented in both the Medium Tree Finch and the Small Tree Finch.</p>
<p>Also, the song of Medium Tree Finches with enlarged nostrils sounds like the song of the Small Tree Finch.</p>
<p><audio preload="metadata" controls="controls" data-duration="1" data-image="" data-title="Small Tree Finches" data-size="29674" data-source="" data-source-url="" data-license="Author provided" data-license-url="">
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Small Tree Finches.
<span class="attribution"><span class="license">Author provided</span><span class="download"><span>29 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1609/audio3-smalltreefinch.mp3">(download)</a></span></span>
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<h2>When species merge</h2>
<p>But confusion among the species and their mating songs may not necessarily be a bad thing for the future survival of individual finches – though it could herald the collapse of species lineages.</p>
<p>Previously, we discovered evidence of <a href="https://www.ncbi.nlm.nih.gov/pubmed/24561597" title="Species collapse via hybridization in Darwin's tree finches">hybridisation in Darwin finches</a>. This is where two separate species of finch breed which could potentially produce a new species, phase out one of the species, or cause the collapse of the two existing species into one.</p>
<p>We observed hybridisation driven by <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jeb.13167" title="Females drive asymmetrical introgression from rare to common species in Darwin's tree finches">female Medium Tree Finches</a> pairing with male Small Tree Finches. </p>
<p>When a female Medium Tree Finch inspects male Small Tree Finches in the forest, she pairs with one who produces high quality song, even if that male is from another species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A Tree Finch with a normal beak and nostril size, so no infection from the parasite.</span>
<span class="attribution"><span class="source">Katharina J Peters</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This female choice seems to be paying dividends, because hybrid pairs with greater genetic diversity also sustained <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.181616" title="Genetic admixture predicts parasite intensity: evidence for increased hybrid performance in Darwin's tree finches">fewer of the parasitic larvae in the nest</a>. And that could lead to fewer birds with infected beaks.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/galapagos-species-are-threatened-by-the-very-tourists-who-flock-to-see-them-86392">Galapagos species are threatened by the very tourists who flock to see them</a>
</strong>
</em>
</p>
<hr>
<p>There are concerted efforts underway to develop control and eradication methods for <em>P. downsi</em> on the Galapagos Islands, building on a collaborative relationship between the Charles Darwin Foundation and the Galapagos National Parks. The <a href="https://www.darwinfoundation.org/en/research/projects/philornis-downsi"><em>Philornis downsi</em> Action Group</a> is an international consortium of concerned scientists working to develop biological control methods.</p>
<p>Our new research is an important step towards understanding how this invasive fly may be changing the evolutionary pathway of Darwin’s finches by literally changing the beak of the finch.</p><img src="https://counter.theconversation.com/content/118586/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>For this project the authors received funding from the Australian Research Council, the Max Planck Institute for Ornithology, the Mohamed bin Zayed Species Conservation Fund, the Ecological Society of Australia, Earthwatch Institute, Club300 Bird Protection, Rufford Small Grants Foundation, the Winifred Violet Scott Trust, the American Bird Conservancy, the Conservation International, the Australian Federation for University Women, and the Royal Society for the Protection of Birds/Birdfair. TAME airlines provided reduced airfares.
Katharina J. Peters is affiliated with Flinders University, Adelaide, Australia, and Massey University, Albany, New Zealand. </span></em></p><p class="fine-print"><em><span>Sonia Kleindorfer 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>An infestation as a chick leads to enlarged nostrils in the beak of Darwin finches, and that affects their mating call.Katharina J. Peters, Postdoctoral fellow, Flinders UniversitySonia Kleindorfer, Professor of Animal Behaviour, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/263992014-05-08T04:36:21Z2014-05-08T04:36:21ZNo fly zone: Darwin’s finches self-fumigate (with a little help)<figure><img src="https://images.theconversation.com/files/47956/original/yy56jsvn-1399448190.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Darwin's finch nestlings are highly vulnerable to a parasitic fly – unless their folks fumigate the nest.</span> <span class="attribution"><span class="source">Sarah A. Knutie</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>When a bird species is threatened by nest parasites, you might think the logical next step is to fumigate – unsurprisingly, though, physically spraying nests (as you might spray an infested house) is disruptive, not to mention dangerous to the birds.</p>
<p>But a group of researchers have successfully fumigated nests of Darwin’s finches on the Galapagos Islands without disrupting the birds’ natural nesting habits. In fact, they used the birds’ nest-building skills to self-fumigate with cotton balls treated with a mild delouser, as reported in <a href="http://www.sciencedirect.com/science/article/pii/S0960982214003509">Cell Biology</a> this week.</p>
<p>Despite being relatively drab in appearance, Darwin’s finches have been described as the “<a href="http://books.google.com.au/books?id=fywDdCnuxQIC&printsec=frontcover&dq=Gal%C3%A1pagos:+A+Natural+History+2006&hl=en&sa=X&ei=7dxpU6iIJsSm8AXgjIHACA&ved=0CEgQ6AEwAA#v=onepage&q=Gal%C3%A1pagos%3A%20A%20Natural%20History%202006&f=false">crown jewels of ornithology</a>” owing to their rapid and observable evolution in the wild.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=628&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=628&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=628&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=789&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=789&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47958/original/chtp4wfy-1399448412.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=789&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 male Darwin’s finch.</span>
<span class="attribution"><span class="source">Sarah A. Knutie</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>After observing different species of the birds, Charles Darwin wrote in The Voyage of the Beagle: </p>
<blockquote>
<p>One might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.</p>
</blockquote>
<p>He theorised that one “immigrant” bird species must have flown over from the mainland and settled in areas with varying ecological conditions, and that natural selection would probably favour “different varieties in the different islands”.</p>
<h2>Survival of the fittest</h2>
<p>Darwin’s finches continue to experience intense natural selection – but recently this selection has come from an introduced fly called <a href="http://www.issg.org/database/species/ecology.asp?si=1400"><em>Philornis downsi</em></a>. This parasite is altering the appearance of Darwin’s finches and threatening their survival. </p>
<p><em>P. downsi</em> is the only ectoparasite that causes measurable fitness costs (such as slower growth, deformation and mortality) in Darwin’s finches. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=825&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=825&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=825&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1037&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1037&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47957/original/9v69t4p5-1399448335.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1037&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 female Darwin’s finch.</span>
<span class="attribution"><span class="source">Sarah A. Knutie</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Feather mites are common in Darwin’s finches but are not known to cause fitness costs. Blood parasites have not been detected and intestinal protozoan parasites are rare. Thus, Darwin’s finch hosts are considered naïve, as they have had little (known) exposure to pathogens in general.</p>
<p>This all changed with the arrival of <em>P. downsi</em>, which is known from collections on the Galapagos Islands in 1964 but was <a href="http://www.cabdirect.org/abstracts/20013154552.html;jsessionid=148F20D49A162BCAFA1291747BFF1348">first discovered</a> in Darwin’s finch nests in 1997.</p>
<p>The fly’s name (<em>phil</em>=loves; <em>ornis</em>=birds) paints a one-sided picture of affinity: fly larvae consume the blood and tissue of nestling birds, leaving Darwin’s finches dead or deformed. </p>
<p>Over the past decade, researchers have made significant advances in understanding the biology of this new host-parasite association. </p>
<p>Each female fly mates with an average of around two males and one to six females each lay an average of five eggs per Darwin’s finch nest. Female <em>P. downsi</em> flies generally carry around 60 eggs, so the female only lays a portion of the available clutch per host nest.</p>
<p>The <em>P. downsi</em> eggs hatch into larvae after the chicks hatch. From in-nest video recordings, we know that Darwin’s finch nestlings are <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7914056">literally being eaten alive</a> by the fly larvae. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/IALArw5bqDY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption"><em>P. downsi</em> fly lays eggs in a Darwin’s finch nest.</span></figcaption>
</figure>
<p>The first developmental stage (or “<a href="http://en.wiktionary.org/wiki/instar">instar</a>”) of the larvae feed on the inside of the nestling beak. The second and third instar larvae live in the nest base from where they feed externally on the finch nestlings. </p>
<p>The initial phase of parasitism inside the beak often leads to beak malformation in surviving adult finches, though most nestlings die in the nest. </p>
<h2>Behavioural changes</h2>
<p>Darwin’s finches are renowned for their diverse feeding behaviours. Now we are witnessing an increasing breadth in anti-parasite behaviours. </p>
<p>There is <a href="http://www.researchgate.net/publication/231794915_Video_analysis_of_hostparasite_interactions_in_nests_of_Darwins_finches">video evidence</a> that Darwin’s finch parents and chicks preen to extract larvae from nares and the nest base, consume encountered larvae in the nest, and that siblings compete to avoid being at the bottom of the nestling pile and hence in close contact with larvae that reside in the nest base. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47959/original/tnvsxzq7-1399448563.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Treated cotton wool woven into a Darwin’s finch nest.</span>
<span class="attribution"><span class="source">Sarah A. Knutie</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Nesting density also correlates with parasite intensity: Darwin’s finch nests with many close neighbours had more <em>P. downsi</em> parasites. </p>
<p>This latest study offers a new perspective for the study of anti-parasite behaviour in nesting Darwin’s finches, and the outcomes of the study provide an exciting approach for hands-on conservation management. </p>
<p>The study shows that Darwin’s finches incorporated pyrethrum-treated cotton into their nest base during nest construction, which lowered parasite intensity during the nesting phase and increased fledging success. </p>
<p>Identifying host behavioural patterns that can be harnessed for conservation outcomes is an exciting new research direction. The conservation behaviour framework identifies <a href="http://beheco.oxfordjournals.org/content/22/2/236.full">key linkages</a> between behaviour and conservation biology derived from three basic themes:</p>
<ol>
<li>anthropogenic impacts on behaviour that impact biodiversity</li>
<li>behaviour-based management</li>
<li>behavioural indicators to other processes of conservation concern.</li>
</ol>
<p>Who knows which species we can help next with similar techniques?</p><img src="https://counter.theconversation.com/content/26399/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sonia Kleindorfer 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>When a bird species is threatened by nest parasites, you might think the logical next step is to fumigate – unsurprisingly, though, physically spraying nests (as you might spray an infested house) is disruptive…Sonia Kleindorfer, Professor of Animal Behaviour, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/263512014-05-07T05:01:34Z2014-05-07T05:01:34ZGiving Darwin’s finches the tools to fight parasites for themselves<figure><img src="https://images.theconversation.com/files/47883/original/wmcd894x-1399380218.jpg?ixlib=rb-1.1.0&rect=977%2C483%2C2863%2C2106&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A finch, doing its own dirty laundry with pesticides.</span> <span class="attribution"><span class="source">Sarah A. Knutie</span></span></figcaption></figure><p>Darwin’s finches, a group of 14 species found only in the Galapagos Islands, are perhaps most well known as one of the inspirations for Charles Darwin’s theory of evolution by natural selection. A classic example of <a href="http://evolution.berkeley.edu/evosite/evo101/VIIB1aAdaptiveRadiation.shtml">adaptive evolutionary radiation</a>, the species are similar having formed from a common ancestor, except for their beaks, which have specialised to tackle different food. </p>
<p>Invasive pests and parasites are a problem in many parts of the word, and have even reached the Galapagos: a parasitic nest fly <a href="http://www.issg.org/database/species/ecology.asp?si=1400"><em>Philornis downsi</em></a> has spread to most islands in the archipelago and is wreaking havoc on Darwin’s eponymous finches and other birds. The fly’s larvae live in the birds’ nests where they feed on the young birds’ blood, sometimes killing the entire brood.</p>
<p>This parasitic fly might be the final nail in the coffin of some critically endangered species of Darwin’s finches, such as the <a href="http://www.birdlife.org.uk/datazone/speciesfactsheet.php?id=9612">mangrove finch</a> and <a href="http://www.birdlife.org/datazone/speciesfactsheet.php?id=9609">medium tree finch</a>. So finding a way of controlling the pest is a top priority at the <a href="http://www.galapagospark.org/">Galapagos National Park</a> and Charles Darwin Research Station (<a href="http://www.darwinfoundation.org/en/science-research/visiting-scientists/">CDRS</a>), and with a novel method of putting pesticides right where it hits the pests – in the nest – we think we’ve found a solution.</p>
<p>One afternoon while lounging in my hammock at CDRS I noticed a female finch land on my laundry line. I snapped a few photos of her as she tugged cotton fibres from a frayed knot. As she flew off with the collected fibres in her beak, I wondered if finches would incorporate cotton treated with a low concentration (1%) of a mild insecticide (<a href="http://npic.orst.edu/factsheets/Permtech.pdf">permethrin</a>) into their nests. We have used permethrin to kill the parasite in Darwin’s finch nests for years without harm to the birds, and if the finches took the cotton they would be threading their nests with the very weapon they need to kill <em>P. downsi</em>. Later that day, I pinned cotton balls sprayed with permethrin to the laundry line. Within a few days, all of the cotton balls had disappeared from the rope.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47884/original/t72qxg3z-1399380481.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">Insecticide-loaded cotton provides finches with pest-control powers.</span>
<span class="attribution"><span class="source">Sarah A. Knutie</span></span>
</figcaption>
</figure>
<p>Inspired by these observations, my colleagues and I designed an experiment in 2013 to test whether Darwin’s finches could be encouraged to “self-fumigate” their nests with cotton balls treated with permethrin. Separately, we also directly sprayed other nests with permethrin to determine if killing the parasites would increase finch nestling survival. </p>
<p>Our research team built 30 cotton dispensers, a bit like suet bird feeders but with cotton balls to pluck instead of food. Some were loaded with pesticide-treated cotton and others with water-treated cotton as a control, and we placed these around our main field site, El Garrapatero on the island of Santa Cruz. </p>
<p>Then over several months, we battled uneven lava rock underfoot and 40°C heat in search of finch nests. During an especially difficult day, I saw for the first time a finch taking cotton from a dispenser and bringing it back to her nest – a nest which turned out to contain nearly two grams of cotton. With more than 85% of the nests we found containing cotton, the finches certainly liked it as a nesting material. But did the pesticide work?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/47885/original/ds6k69k5-1399380581.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Finches nest, with added parasite protection.</span>
<span class="attribution"><span class="source">Sarah A. Knutie</span></span>
</figcaption>
</figure>
<p>We found that nests which contained more than one gramme of permethrin-treated cotton (62% of nests) were virtually parasite-free, compared to nests with untreated cotton, which contained on average 30 parasites. Those nests that were sprayed directly with permethrin also had fewer parasites and more surviving nestlings. Given the tools to do so, finches can carry out their own pest control.</p>
<p>Since the fly is found almost everywhere in the Galapagos, we do not believe that it will develop resistance to permethrin, especially if the dispensaries are used over a smaller area. We believe that self-fumigation can be especially useful for endangered species such as the mangrove finch – this Darwin’s finch species is down to fewer than 80 remaining individuals. We presented our findings, <a href="http://www.sciencedirect.com/science/article/pii/S0960982214003509">now published</a> in Current Biology, to researchers at CDRS, who are now putting out untreated cotton for mangrove finches to determine if they will be interested in the nest material. Self-fumigation provides an immediate solution to the parasite problem while other long-term methods are developed.</p>
<p>Of course there are other species of birds that are hurt by parasites, and if those birds too can be encouraged to incorporate fumigated cotton into their nests, they should be able to reap the benefits too. For example, <a href="http://ibc.lynxeds.com/family/hawaiian-honeycreepers-drepanididae">Hawaiian honeycreepers</a> become infested with feather lice, birds in Puerto Rico are afflicted by <em>Philornis</em> flies, and the endangered <a href="http://edis.ifas.ufl.edu/uw306">Florida scrub jay</a> suffers from parasitic fleas.</p>
<p>The same method might be used for the <a href="http://www.defenders.org/prairie-dog/basic-facts">black-tailed prairie dog</a>, which while removed from the endangered species list is still declining on the Great Plains and is affected by flea-bourne plague. Spraying permethrin directly into burrows has been used but is labour-intensive – it might be possible to spray the pesticide onto vegetation that the animals then drag into their burrows.</p><img src="https://counter.theconversation.com/content/26351/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah A. Knutie was funded by a US National Science Foundation grant.</span></em></p>Darwin’s finches, a group of 14 species found only in the Galapagos Islands, are perhaps most well known as one of the inspirations for Charles Darwin’s theory of evolution by natural selection. A classic…Sarah A. Knutie, PhD researcher, University of UtahLicensed as Creative Commons – attribution, no derivatives.