Swallows developing shorter wings to avoid being struck by cars

Science News : Cliff swallows in the US Midwest appear to be adapting quickly to the ever-growing number of people, cars, and roadways. Not only have they discovered the benefits of building their nests on the undersides of highway bridges and overpasses, which afford more protection from storms than do the sides of cliffs, they also are developing shorter wing spans, which allow them better maneuverability to avoid being struck by cars. A pair of researchers has been studying the swallows since the 1980s, counting nests and picking up dead birds. In a paper published online in Current Biology, the researchers say that the number of dead birds has been decreasing sharply each year and that those that died had slightly longer wing spans compared with the at-large population. “It’s amazing what natural selection can do,” said the University of Tulsa’s Charles Brown, one of the authors of the study.