Autumn…and geese fly high overhead in V-formation. But what about that V-formation, angling outward through the sky? This phenomenon — a kind of synchronized, aerial tailgating — marks the flight of flocks of larger birds, like geese or pelicans. Most observers believe that each bird behind the leader is taking advantage of the lift of a corkscrew of air coming off the wingtips of the bird in front. This corkscrew updraft is called a tip vortex, and it enables the geese to save considerable energy during long flights. The V-formation may also enhance birds’ ability to see and hear each other, thus avoiding mid-air collisions. Small birds probably do not create enough of an updraft to help others in the flock and don’t fly in vees.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.