...and this just in from the Washington Post, this AM.
Bernie
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-- Shankar Vedantam
City Birds Hit the High Notes
Even birds, it seems, sometimes need to raise their voices to be
heard over the din of the city.
Hans Slabbekoorn and Margriet Peet of Leiden University in the
Netherlands studied the mating songs of a species of bird known as
the great titmouse living in different parts of the Dutch city of
Leiden.
Male birds living in the noisier parts of the city tended to sing
higher notes, which other birds can hear more easily above the racket
around them, than their counterparts in the quieter parts of the
city, the researchers found.
Although it is possible that birds choose places to live that
match their songs better, the researchers said it was more likely
that the birds adjusted the songs to their habitat.
"Our findings show, to our knowledge for the first time, that
human-altered environments might change the communication signals of
a wild bird species," the researchers wrote in the July 17 issue of
the journal Nature.
Because mating calls are crucial for the survival of a species,
those that are unable to make that kind of adjustment may be at
greater risk of extinction, the researchers said.
"Cars, planes and all sorts of machinery create a new selection
pressure on wildlife species that use acoustic signals to achieve
reproductive success," they wrote.
"This might create two groups of species: one that can adapt their
signals to the competing noise, and another that cannot."
-- Rob Stein
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