Male hummingbirds whistle with tails to attract mates : study

Male Costa’s hummingbirds in North America use their tail feathers to create a whistling sound to impress their female counterparts, a US-Canada research has found. The birds twist their tails sideways while flying by females, who chose their mates according to their speeds. The diving fashion increases the apparent speed due to Doppler effect, said researchers.                                                     ( News Source : inshorts.com )