Sparrows Actually Change Their Tune To Sing Over the Noise Of the City
Well it turns out city-dwellers aren’t the only ones miffed by urban noise pollution. Research has long suggested that wildlife – and birds in particular – may be impacted by the man-made sounds of the city, from car horns to traffic congestion. A new study confirms that sparrows in the Presidio District of San Francisco appear to have changed their tune and raised their voices to be heard over the increasingly noisy racket of the Golden Gate Bridge.
The researchers, George Mason’s David Luther and Louisiana State’s Elizabeth Derryberry, compared modern birdsong in the city to recordings of sparrows in the area taken in 1969. They also looked at historic noise-level data from the Environmental Protection Agency and San Francisco Department of Health, as well as traffic volumes over the Golden Gate Bridge across this time period.
They found that as noise in the city increased, so too did the pitch, or frequency, of the male white-crowned sparrow song. Higher frequencies of song allow the birds to keep twittering at each other over the low-frequency ambient noise of rumbling cars. Even more surprising, the authors write in the journal Animal Behaviour, the birds also seem in the last four decades to have literally changed their repertoire. […]
It’s probably good news for these sparrows that they’ve figured out how to adapt (and good news for urban bird-lovers that this wildlife isn’t simply fleeing the city all together). But there’s also something sort of disturbing about the implication that cities can distort the natural environment right down to birdsong. In some ways, noise matters even more for birds than it does for humans: Birds sing to defend their territory and to attract mates (life’s two most important goals!), and excessive noise threatens that.
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