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Study Finds Urban Stresses Cause Birds To Abandon Eggs

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Boise State University

A bird of prey can get so stressed out by city noise, it will abandon its nest – with eggs still in it. That's according to a new study by researchers at Boise State University. The study suggests human disturbances affect the American kestrel more than previously thought.

Busy roads have a certain appeal for birds of prey like the kestrel. The combination of power poles and open space makes highways prime real estate for spotting rodents.

But the researchers say these areas turn out to be an “ecological trap.” When it comes time to nest, blood tests show American kestrels that choose high-traffic areas develop heightened levels of a stress hormone. And that makes them leave their nests.

“And so you would find five cold eggs and no adults would come back to that nest,” says Biologist Julie Heath. She co-authored the new study, which was published in the Journal of Applied Ecology. She says the kestrel builds its nest inside a cavity and relies on its hearing.

“We think that in high noise areas -- it's masking the cues they would normally use to evaluate what's going on outside.”

Female birds nesting near busy places like I-84 in southern Idaho were found to be 10 times more likely to abandon their nest.

Heath says the study indicates that a bird's presence in an area doesn't necessarily mean that area is good habitat.

On the Web:

Video: Ecological Kestrel Research - Boise State University
American kestrel nesting study - Journal of Applied Ecology