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12 August 2014 6:30 pm 2 Comments
Every fall, countless songbirds migrate from their breeding grounds in the United States and Canada. Often flying at night to avoid hawks, the animals head south to spend the winter in Mexico and Central America. But exactly where many of them go, and how they get there, has been something of a mystery. Now, a team has shown that analyzing DNA in feathers can provide new details about bird migrations. Although the technique is still in the proof-of-principle stage, it “could be an immensely powerful tool in implementing conservation measures for the most at-risk bird populations with fine-scale precision,” says Jeff Wells of the Boreal Songbird Initiative in Seattle, Washington.
Ornithologists have many ways to track migratory birds. The most common is to put small identification bands on their legs. The trouble is that netters recapture only a tiny fraction of the banded birds. Electronic tracking devices can work well for individual birds, but may not yield insights for an entire population. More recently, researchers have shown that the ratio of isotopes in feathers can provide a rough guide to where a bird has been feeding, because the feather ratios mirror those of food sources. Analysis of mitochondrial and nuclear genes has also offered clues, for example confirming that some birds have geographically distinct breeding populations. But even those techniques couldn’t tease out fine-grained differences in where birds summer and winter. “This is a really big issue,” because conservation groups need to know where to spend their resources to best effect, says Robert Fleischer, a geneticist at the Smithsonian Conservation Biology Institute in Washington D.C.
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