Fastest Wings on Earth Show Extremes of Sexual Selection

With feathers that resonate at precisely 1,500 hertz, the male club-winged manakin is perhaps the bird world’s most perfectly tuned example of sexual selection.

By pinning down the frequency, researchers have completed a long investigation into the bird’s sonic physiology and showed just how far some guys go to impress the ladies. According to scientists, the fundamental anatomy of the wings has been completely reworked to play a sound for courtship.

The early work focused on the anatomical peculiarities of the males’ wings. One odd middle feather has seven ridges, while an adjacent feather has an especially thick tip. A high-speed video recording of males making their trademark sounds showed they shake their wings 107 times per second. That’s faster than a hummingbird’s wingbeats, and faster than was even thought to be possible in a vertebrate.

The sound was replicated by putting feathers inside an apparatus that measured their acoustic resonance at high-speed vibrations. At 1,500 vibrations per second, and not a few more or less, the feathers’ resonance swelled.

That number is predicted by the feathers: seven ridge bumps, multiplied by two — the upstroke and downstroke — multiplied by 107 wingbeats per second equals a frequency of 1498 hertz, almost exactly what they measured in the lab.



Original article here.