Hummingbirds 'sing' with their tail feathers to impress the females
Costa's hummingbird males try to impress the females by dive-bombing them at over 80 kilometres per hour and using the incredible acceleration and speed to generate a song with their tail feathers.
Most hummingbird species make their presence known the female by hurtling themselves right at the female propelling the sounds of the vibrating tail feathers with a Doppler shift.
Costa's hummingbirds do something unique: their dive trajectory is more to the side than aimed directly down at the female.
Shake your tail feathers
The research, led by Emily Mistick, currently at the University of British Columbia, discovered that the Costa's hummingbird uses this side-dive to conceal less about their speed and strength.
Most species of hummingbirds take advantage of the Doppler shift to make them sound faster and therefore much more attractive.
The Costa's hummingbird's side trajectory means that they can't take advantage of the Doppler shift but that the female gets to choose her mate based more on his athletic prowess than just a quirk of physics.
But, the problem with diving to her side is that the sound is directed away from the female.
The Costa's hummingbird has found a solution to this. He twists his tail feathers inwards that directs the sound away from his dive angle directly toward the female. And it sounds like this:
Many animals use indirect displays of male strength to impress the female. The hummingbirds are presumably doing the same thing, using their amazing speed to impress the female into going into the woods to mate with him.
Whether it works has not been studied yet, but the fact that season after season produces little baby hummingbirds suggests that there is something sexy about the males tail song.