PCBs Make Birds Sing Out of Tune

by kespeland on August 26, 2008

A story in New Scientist reports on the research of Sara DeLeon, a graduate student at Cornell University, who is exploring the effects of pollutants on animal communication. Animals communicate for all kinds of reasons, including finding a mate. So any disruptions to their ability to communicate could affect populations.

DeLeon focused on PCBs (polychlorinated biphenyls), which power plants used up until the 1970s. The EPA says PCBs can affect development and cause cancer. And even though they’re no longer produced or used in the U.S., they remain in the environment–stuck to sediments in rivers, released in rain, gobbled up inadvertently by organisms, which are in turn eaten by other organisms, magnifying the presence of this compound (a process scientists call “bioaccumulation”). They’re in Kentucky, too.

So DeLeon decided to traipse around New York’s Hudson River Valley, where PCBs are known to persist, and check in on some bird populations. Like a radio journalist, she recorded the bird songs of chickadees and sparrows. When she got the sound back to her lab, she was able to see some differences in the sound wave forms. Birds without any exposure to PCBs sang in tune, with typical variations on a two note theme. Birds exposed to the pollutant couldn’t seem to carry a tune – their improvisations were all over the place. And since chickadees, for example, pick a mate, in part, based on the quality of the song, this could be bad news for these populations.

Environmental pressures of all kinds may be changing bird songs. Scientists have found that city birds aren’t singing as much at dawn because of the competing noises. But the noise may also be causing them to alter their songs.

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