Bird sings through feathers

Solving a longstanding puzzle among bird experts, scientists have found that the sharp, violin-like sounds of a South American songbird come not from the beak but from a suite of specially evolved, vibrating feathers.

A new study offers the first hard evidence that birds use feathers for audible communication as well as for flight and warmth.

In 2005 Kimberly Bostwick, curator of birds and mammals at the Cornell University of Vertebrates in Ithaca, New York, theorized that the male club-winged manakin—a tiny bird of the Andean cloud forest—was vibrating a club-shaped wing feather against a neighbouring, ridged feather to "sing" when trying to attract females.



Proving the feather-song connection, though, would be a huge challenge. The team used lasers to monitor vibrations as they were oscillated by a lab device called a mini-shaker. The special feathers vibrated at exactly 1500 hertz — proving they're responsible for the strange sounds.

But there's a twist: Bostwick was surprised to find that club and the ridged feathers aren't a duet, but part of a chamber orchestra.

Individually the manakin's "regular" feathers didn't resonate like the special ones. But when the nine feathers closest to the special feathers were still attached to the ligaments, they vibrated at around 1500 hertz, harmonized with the club feathers, and amplified the volume of the sound.