Darwin’s finches on the Galapagos Islands are once again providing insights into the theory of evolution, with two studies investigating their dealings with the parasitic avian vampire fly (Philornis downsi). One study investigated which species of finch proved to be the most successful hosts for the flies, while a second study looked at how the birds cope with being infected by the parasites. The insights will help researchers to maintain the finch population while also providing strategies for dealing with other parasitic species around the world.

The avian vampire fly (Philornis downsi) was accidentally introduced to one island in the Galapagos back in the1960s, with its blood sucking larvae now spread across the islands and killing the offspring of most of the land birds.

The fly larvae feed on the blood and tissue of nestling birds, including feeding inside the birds’ nostrils.

Now, two new studies have explored how the various species of finches across the islands, whose discovery by Charles Darwin was pivotal to his research into natural selection and evolution, have been dealing with the fly, potentially providing further insight into the evolutionary pathways of introduced parasites.

In one study, published in the Nature journal Scientific Reports and led by Lauren Common, PhD Candidate in the Flinders University BirdLab, the researchers investigated which species of finch proved to be the most successful hosts for the flies.

The team found the fly’s larvae were most abundant and had the best survival rates inside the nests of the critically endangered medium tree finch, which lives only on Floreana Island, but had less success in the nests of hybrid tree finches.

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