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Tuesday, March 19, 2013

High-speed evolution: Road kill causes birds' wings to become shorter in just three decades

Cliff swallows that swoop over roads to eat insects attracted to the heat of the pavement risk being hit by cars. The risk is so great that in just three decades, a measurable different in wing length has spread through the population. This is the summary of a paper in Current Biology:

During a 30-year study on social behavior and coloniality of cliff swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, we found that the frequency of road-killed swallows declined sharply over the 30 years following the birds’ occupancy of roadside nesting sites and that birds killed on roads had longer wings than the population at large.

Here's a story in ScienceNow about the study. It's the finest example I've ever seen of fast evolution occurring in mammals.