Saving Darwin’s Finches

darwin finch npr
Darwin’s finches, known for being instrumental in the development of the theory of evolution via natural selection, were under threat from an invasive parasitic fly since about 1997. Researchers recently developed a method for protecting the birds using cotton balls (Image source:

In the first couple months of my senior year of undergrad, I devoted a lot of my free time to putting together an application for a Fulbright research grant. Usually you want to spend about six months or so putting these applications together, to get connected with a foreign institution that’ll house you and design a project to work on, select your references, craft your essays, and do a language evaluation along with a faculty interview. Never having been one to do things the easy way, I decided to cram all that into about five or six weeks the same semester I was working on my biology senior thesis and getting my ass handed to me by immunology.

My goal was to go down to the Galapagos and spend a year working with the Charles Darwin Foundation on a restoration project looking to protect large populations of birds that were being threatened by an invasive fly whose larvae were wreaking havoc on newborn nestlings. I ended up not getting the grant but as a result of the whole application process I managed to pick up a fair amount of knowledge about the invasive fly, Philornis downsi (although it should be noted I did by some miracle manage to get alternate status, basically being wait-listed, which I’m still pretty proud of).

Now imagine my delighted surprise when earlier today I caught sight of a story from NPR about researchers using insecticide-soaked cotton balls to combat what else but Philornis downsi. According to NPR, the fly was introduced to the islands in 1997, most likely via ships or planes coming from the mainland of Ecuador.

Darwin’s finches, when presented with insecticide-soaked cotton balls, quickly incorporated them into their nests, thus fumigating them and helping to protect their nestlings (Image source:

Dale Clayton, a co-author of the study reporting the group’s cottony successes in Current Biology, told Reuters that in some years the flies killed off 100% of nestlings. That’s kind of a big deal given that many of the species being parasitized fall within the famous group of Darwin’s finches. You don’t exactly want to be part of the generation of ecologists that let Darwin’s finches go locally extinct in the Galapagos. It’s just bad press.

So skip forward to the publication of this new study, wherein researches set out cotton balls soaked in insecticide for the birds to take back and incorporate into their nests. The group found that in those nests where insecticide-soaked cotton had been woven in, there were half as many fly larvae on average compared to cotton balls soaked in water. When the amount of insecticide was over one gram, there were often no larvae present at all. That’s a pretty impressive result to get and definitely good news for Darwin’s finches.

Now when I was looking to get in on this P. downsi action back in the day, the Foundation was still gathering a lot of information on the fly’s life history, basically encompassing everything it does between its egg being laid and the fly dying. They were looking into how far it dispersed on a single island, how much it traveled between islands, what kind of food sources it preferred, whether it was still being introduced by ships coming in, and a lot of other things, all trying to find some point in its life at which they could try and attack it. It seems a bit ironic then that this new and highly effective strategy should end up arising, not from knowledge of the fly’s behavior, but of the birds’. So, how did that come about? By chance really.

Sarah Knutie, a conservation ecologist at the University of Utah, told Scientific American how she was sitting on the Foundation’s porch on Santa Cruz, when she saw a finch take a laundry line, carrying it away to help build its nest. She set out some cotton balls, just as a test, and found that that the birds took those too. So she tentatively suggested using the cotton balls as a means of self-fumigating nests. In January 2013 she went on the crow-funding website RocketHub to raise plane fare and a supply budget and by the breeding season had her project all ready.

The group managed to find 26 nests within their study area (which was about 600 x 80 meters) and of those 26, 22 had the group’s cotton balls woven into them. As I said before, those with insecticide-soaked cotton had half as many larvae, and seven of the eight nests with over one gram of insecticide had no larvae whatsoever. The insecticide, permethrin, is often used in lice shampoo and is apparently effective against P. downsi as well, but safe for the newborn birds’ development.

So beyond just being a great bit of news about saving Darwin’s finches in the Galapagos, this story highlights a fairly new possibility in conservation ecology: crowd-funding. When I originally got in contact with the Foundation during my application, one of the first things they warned about was the possibility of running out of money. In the past they had brought guest researchers down to work with them, only to have the project financially stall, leaving researchers in the lurch, sometimes for months. At the time, that was a pretty disheartening thing to hear, but seeing this story and the apparent successes of small-scale crowd-funded research, even my cynical heart can’t help but feel a little bit more hopeful about conservation work’s future.


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