for National Geographic News
Plain-tailed wrens sing what is perhaps the most complex and coordinated birdsong known, researchers have discovered. But you might not realize it just by listening.
"It sounds rather boring, truth be told," said Peter Slater, a biologist at the University of St. Andrews in Scotland.
"It's only when you realize that it's several birds singing in a perfectly synchronized form that it becomes impressive.
"At a distance you wouldn't know it was more than one bird."
The wrens, residents of Ecuador (South America map), sing a male-female duet similar to many other tropical bird species.
But instead of a two-part a-b pattern, the plain-tailed wrens sing a four-part repeating chorus of a-b-c-d, a-b-c-d.
The males sing the a and c parts. Females sing the b and d.
Several males and females will sing the chorus at once, at times singing together for more than two minutes (listen to the wrens' song).
"All the more impressive," Slater added, "is for all these four different phrases, every one has about fifteen different varieties."
To get the chorus going, a single male-female pair starts with a particular pattern. Other males and females join the chorus once the pattern is set.
Occasionally the birds will even switch the pattern mid-song, Slater adds.
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