Tuesday, September 23, 2008

Duelling Banjos Ain't Got Nuthin On Duelling Birdsong

Birds' Harmonious Duets Can Be 'Aggressive Audio Warfare,'
Study Finds -- eScienceNews


Researchers reporting in the September 4th Current Biology, a Cell Press publication, have new insight into the motivating factors that drive breeding pairs of some tropical bird species to sing duets. Those duets can be so closely matched that human listeners often mistake them for solos. They now report evidence that male and female rufous-and-white wren partners sing as a way of keeping track of one another when they are apart. But the duets, as pleasant as they may sound, also have a more sinister purpose. During confrontations with rivals, the wrens essentially duel one another with their duets.

The discovery was made possible by sophisticated sound recording technology developed by the University of Windsor and Cornell University team. That system, including eight microphones recording to a single laptop computer, allowed them to triangulate the duetting birds' positions in the dense tropical forests of Costa Rica where they live.

"Your first impression after you hear the duet of a pair of tropical birds is one of great harmony and cooperation," said Daniel Mennill of the University of Windsor. "Their duets require coordination and synchronization, and my multi-microphone recordings confirm that birds do coordinate their activities by performing duets. But there is a darker side to duetting; tropical birds also perform duets in very aggressive contexts, and respond with special aggression to rival individuals of the same sex. Their voices are beautiful harmonies, but they're also aggressive audio warfare."

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