Anna's Hummingbird by Hayley Crews
The mating display of the male Anna’s Hummingbirds is dramatic and loud! During breeding season males climb into the air 100 feet or more and then plummet in a near-vertical dive, ending with an explosive chirp that sounds much like their vocalizations when perched, only much louder!
Since the 1940s, ornithologists have debated whether this chirp is just a loud vocal sound or a different sound produced by some unknown mechanical structure. Two years ago UC Berkeley students used high-speed camera recordings of the dive-bomber display of Anna’s Hummingbirds, plus wind tunnel tests, to show that their outer tail feathers vibrate like a reed in a clarinet. The bird’s split-second tail spread at dive speed (up to 50 miles an hour) produces the brief burst of loud sound. The loud tail-feather chirp serves to impress females as it discourages rivals or startles predators.
To read more about this interesting discovery, read Cornell Lab of Ornithology’s All About Birds: The Mysterious Squeak of the Anna’s Hummingbird by Irby Lovette or Anna’s hummingbird chirps with its tail by Robert Sanders.