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BOB HIRSHON (host):
Fast-paced evolution. I’m Bob Hirshon and this is Science Update.
In many places, the top-level predator is an omnivorous killing machine the size of a hippo and the speed of a cheetah. It’s the car, and researchers have learned that at least one bird population has actually evolved to avoid it. Cliff swallows nest by the thousands in highway overpasses. In the journal Current Biology, researchers report that over the past thirty years, fewer of the birds have fallen prey to cars. Over the same period, the birds’ wings have gotten shorter. They suspect that short winged birds are better able to avoid the high-speed predators.
In other bird news, researchers in Japan have found that although roosters sometimes crow at odd times, when placed in round the clock dim lighting, they crow right on schedule, just before dawn. Proving they do have an accurate internal clock—even if they don’t always rely on it. I’m Bob Hirshon, for AAAS, the science society.
