From New Scientist:
Good vibrations get a club-winged manakin going
* 00:01 11 November 2009
by Phil McKenna
CLUB-shaped feathers are no good for flying, but when it comes to courting they can be music to a mate’s ears.
The irregular structure of these heavy, specialised feathers is responsible for creating the club-winged manakin’s unique high-pitched courtship song, say Kimberly Bostwick and colleagues at Cornell University in Ithaca, New York. The songbird (Machaeropterus deliciosus) uses these feathers for stridulation, a rubbing mechanism commonly used by insects such as crickets.
One feather on each wing has seven ridges along its central vane. The stiff, curved tip of an adjacent feather strikes the ridges every time the bird raises it wings over its back and shakes its feathers. The repeated striking causes adjacent clubbed feathers to vibrate at high speed.
A small bird called a golden-collared manakin performs a tough, complex, tiring courtship dance that leaves its heart rate at some of the highest levels in the avian world, biologists say: here.