Why Do Canada Geese Fly In V Formation?

It is the very symbol of the wild: the V formation of Canada geese, honking musically as they cross the sky every spring and fall. But why the arrow shape? It's long been assumed that Canada geese and other large migrating birds arrange themselves into a V-shaped pattern because of its aerodynamic advantages. The wings of a bird in flight create a downwash and an upwash of air, with most of the upwash concentrated behind and just beyond the tips of the wings. A bird that follows in this upwashing air is lifted slightly, encountering less drag than it would if it flew solo. With the exception of the trailblazing bird in the lead, all the members of the flock should gain an advantage from the bird ahead, thus saving energy during long flights.

The V formation is efficient, however, only if the birds fly within about one-quarter wingspan of one another and position themselves with their wings slightly overlapped. Since geese in a flock are seldom that close or spaced apart that precisely, the purpose of the formation remains a mystery. It could be that geese organize themselves in echelons simply because the arrangement allows each bird to see clearly, avoid collisions with the neighbors, and stay securely within the flock. While arrowlike shape has become synonymous with Canada geese, these birds actually fly in various configurations—a straight line, a double or triple arrow, even a random jumble.