How Cotton Balls Helped Save Darwin's Finches

Serious problem, simple fix. Researchers on the Galapagos Islands have helped Darwin's finches protect their nests from a dangerous new parasite, reports Scientific American. The simple fix: Scientists left cotton balls laced with a mild pesticide for the birds to take, and the finches happily wove them into their nests. Result: Nineteen of 20 nests with the cotton balls were free of the blood-sucking parasite, which has been blamed for declining finch populations of late, reports University Herald.

The pesticide is permethrin, which Reuters explains is mild enough to treat head lice in humans. It has no effect on the birds or their offpsring, but it kills the larvae of the parasitic flies known as Philornis downsi. "This parasite is not historically found in the Galapagos Islands and, therefore, Darwin's finches have not had enough time to evolve defenses against the parasites," says one of the researchers. One of his colleagues struck upon the idea when she saw the birds stealing bits of a laundry line for their nests. (Read about another Pacific island discovery involving a 63-year-old bird.)