They’re one of the most annoying things about living in a big city, but pigeons — aka the rats of the sky — have developed a pretty clever defence mechanism designed to scare off attackers: a loud and repeated clapping noise that you probably hear when you scare an annoying pigeon into fleeing.
As BBC Earth Productions discovered by studying a pigeon’s takeoff with a high-speed camera, the noise seems to be generated as the bird’s muscular wings and stiff feathers clap together on the upswing. The footage also reveals how graceful a pigeon and almost makes you want to like them, until you remember the mountain of crap on your air conditioner and reach for a broom.