Scientists Help Finches Build Parasite-Resistant Nests

By Joelle Renstrom | 7 years ago

FinchHave you ever watched a nature documentary and realized with horror that the lion is about to catch — and shred — the gazelle? Or worse, that the pod of killer whales that have been following a mother grey whale and her calf for hours have successfully tired them out and are about to separate the calf from its mother so they can eat it? Every time I watch one of these scenes unfold, I wonder whether the folks behind the cameras might stop the carnage. Even though I know they’re not supposed to intervene with the natural, if sometimes brutal, events that transpire in the animal world, I still sometimes hope they will. And in this next story, scientists did intervene to help save the Galapagos finch. The unobtrusive way they did it is pretty brilliant.

The Galapagos finch, also known as Darwin’s finch, has been dying off due to parasitic flies that were first identified on the Galapagos Islands just under 20 years ago. The flies were brought from elsewhere, and because they’re not native to the environment, the finches didn’t have a defense mechanism or antibodies to prevent getting ravaged. One of the scientists to work on the problem noted that it’s common for the parasites to kill all of the finch hatchlings in a nest, and that finding a solution was imperative to prevent eventual extinction.

A study that recently appeared in Current Biology detailed scientists’ ingenious solution to the problem — providing finches nesting materials soaked with insecticides. The scientists soaked cotton balls in chemicals commonly found in anti-lice shampoo designed to kill the parasitic flies and then made the cotton balls available to the finches, who used them along with other materials to build their nests. One of the co-authors of the study had the idea when she saw the finches take a laundry line from the research station.

Funded by a campaign on Rockethub, the team set out 30 cotton ball dispensers over a 600- by 80-meter site between January and April. Half of those dispensers released insecticide-laden cotton balls, while the other half released cotton balls soaked in water. After the finch breeding season ended in April, the team found 26 nests; 22 of those had incorporated the cotton. Those with the insecticide-treated cotton contained 50% fewer parasites than those with the “placebo” cotton. They also discovered that the more saturated the cotton balls were with the insecticide, the fewer parasites they had — seven nests containing a gram or more of insecticide were parasite-free.

It may not be natural selection, but then again, the arrival of foreign parasites because of human travel isn’t either.