In today’s San Francisco Chronicle is a story about two researchers finally finding out how the male Anna’s hummingbird makes its very loud and, for a hummingbird at least, low-frequency chirp when it dives in its attempt to woo a mate. Out here in the boondocks we have tons (grams?) of hummingbirds and see the ritual often where the male bird flies way up in the air a hundred feet or so, then does a power dive. At the bottom of the dive, he flies horizontally in an arc and lets out a very loud “chorp” sound. It seems way too loud and low for such a tiny creature whose normal vocalizations are more like mouse squeaks.
Turns out they aren’t chirping at all, but using their speed to make their quickly opened tail feathers vibrate as the wind passes through them, much like the reed action of a woodwind instrument. I’ve observed that they use the humming of their wing feathers as a threat to rivals. Around the two feeders we have outside you can hear the wing beats get much louder when they try to scare off an intruder. Hey, when you only weigh five-eighths of an ounce, you use whatever you got.
Useless fact: Hummingbirds can’t walk; their feet can only grasp. Same as the acorn woodpecker, though the woodpecker can at least hop. Chickens, bless their hearts, can both walk and grasp. And fly. Cluck. Coo. Don’t get me started about chickens.