Millions of birds die in the US each year as they collide with moving vehicles. In spite of this things have been looking up, at least in the case of cliff swallows. Today's swallows are hit less often, thanks to shorter wingspans that may help them take off more quickly and pivot away from passing cars. The findings, reported in the Cell Press journal Current Biology on March 18, show that urban environments can be evolutionary hotspots.
"Evolution is an ongoing process, and all thisroads, SUVs, and allis part of nature or 'the wild'; they exert selection pressures in a way we don't usually think about," says Charles R. Brown of the University of Tulsa.