By Susan Milius
ALBUQUERQUE — Baby bluebirds don’t survive as well near rumbling traffic and other human din as they do amid natural lullabies.
In a Virginia study, 35 percent more chicks died in the noisiest nests than in the most remote ones. Researchers found that chicks didn’t adjust for the noise by begging louder or at different frequencies. So parents may not have gotten the right cues for nestling care, behavioral ecologist John Swaddle suggested June 12 at the annual meeting of the Animal Behavior Society.
Until recently, most research on how human-made noise discombobulates birds has focused on how adults adjust their songs (or don’t) or on what species will nest at all among the din. Research is now turning to how noise might directly affect the success of a species. One earlier study on reproductive success, in common European birds called great tits, found smaller clutches near roaring highways.