I'm too
sexy for these feathers. So says the male club-winged manakin. The
clumsy but sweet singing resident of the Andes mountains is a textbook example
of runaway sexual selection. That means the small bird species has
rapidly evolved a certain ornamental trait that attracts the opposite sex but
harms its chances of survival. In the case of the club-winged manakin, it has
"selected" an elaborate mating song over the ability to fly well. The
song is produced by their sophisticated "spoon-and-washboard" wings.
The wings have extra wide bones, with special ligaments, that beat up to 100
times per second. Their "spoon" feathers rub over ridged
"washboard" feathers to produce 14 sounds per oscillation, or 1400
sounds per minute. While this makes for an amazing song—one that drives the
females crazy—it requires their wing bones to be malformed and solid instead of
hollow. Which unfortunately means they can barely fly.
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