![]() As you may recall from those textbook chapters, there are 14 – 18 finch species (species delineations are constantly changing in this well-studied family) spread across the Galápagos archipelago. Yes, these are the same finches that star in Evolution 101 textbook figures, exemplifying the power of natural selection to shape bodily traits and ultimately, form new species**. This bird, the vampire ground finch, is one of Darwin’s famous Galapagos finches. Well, your distrust would be justified: this ground finch is a literal vampire.ĭon’t let the boring brown look of this finch fool you. So, when I mention Geospiza difficiulus septentrionalis, an unassuming “ little brown job” that lives on the Galápagos islands west of Ecuador, you might be hesitant to believe that this species is just another “normal” bird. It was evident that the little vampires were not merely lapping up a few drops of blood.We’ve seen cute, seemingly-innocent songbirds turn out to be murderous monsters on this blog before. And when it all gets too much, they can be forced to fly away.Īnd who can blame them? When we captured finches to collect samples, and found gullets full of blood, and beaks stained red. Though they can tolerate the finches, the small bloodsuckers are a nuisance that the boobies do try to get rid of. Interestingly, the finches seem to act like a true parasite, inflicting enough damage to secure a meal without excessively harming the host.įor the boobies, the whole experience really is very similar to a human being attacked by mosquitos. 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. The boobies are incredibly vulnerable when tending to nests and chicks, as they are reluctant to abandon them, even temporarily. Left: a vampire finch crop (food store in the throat) full of blood. 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. 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. Getting there was extremely challenging as there are no beaches for landing a boat. ![]() Two of us, Daniel and Jaime, went to Darwin and Wolf along with professor Albert Uy to study these fascinating finches on islands that are very rarely visited, even by researchers. ![]() When we studied the microbes found in the guts of these vampire finches in search of adaptations we found a very different microbiome from any other species of Darwin’s finches, presumably caused by the blood diet. And once a blood-feeder pierces the skin, it still needs a way to consume and digest the blood. Natural selection appears to have fine-tuned the vampire finch beak for skin-piercing and blood-sucking, as the birds have evolved particularly long and pointy beaks compared to non-blood-feeding populations on other islands. 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. Thus, the finches capitalised on an alternative food resource, blood from the boobies, and earned themselves the nickname “vampire finches”.Ī vampire finch feeds from an open wound on a Nazca booby. 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. 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.Įventually however, the removal of parasites led to open skin lesions on the boobies, allowing the finches to consume blood. Over time, it seems the finches likely evolved to eat parasites found in the feathers and on the skin of the boobies. Kiyoko Gotanda, Author providedĪt some point in the last half million years – 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.
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