SSS 2012-04-09

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City dwellers¹ compete with the din² of traffic to be heard. And it’s not just urban humans. Sparrows living in San Francisco's Presidio district actually tweet their tunes⁴ in a higher register than they did in the past, to be heard over the rumble⁵ of cars on the nearby Golden Gate Bridge. So says a study in the journal Animal Behavior.

 

Researchers compared white-crowned sparrow songs recorded in 1969 and 2005. Over that time span, ambient noise levels went up. And the bird calls were essentially⁶ the same—but the more recent one was higher in pitch. The change presumably allows the song to better penetrate⁷ the traffic noise.

 

The modern calls carry more weight with the birds, too. Because when male sparrows heard the 2005 recordings⁸ played back in their territory, they responded more aggressively—swooping in on the speaker with a “get outta here" chirp⁹ and flapping their wings at the suspected intruder.

 

The researchers say most species simply can't handle the noise and cramped¹⁰ habitats of the city, and head to the country. The adaptable¹¹ sparrow, however, simply changed its tune³.

 

Thanks for the minute for Scientific American 60 second Science, I am Christopher Intagliata.

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