Why do geese fly in V formations during migration?

Geese, which belong to the family Anatidae, fly in V-formations during migration primarily to conserve energy. By arranging themselves in this characteristic shape, the birds are able to take advantage of air currents, specifically vortices, created by the wing tips of the birds flying in front of them.12

This formation is a common migratory behavior among several species, including ducks, pelicans, and cranes. In some species, such as the northern bald ibis, individuals take turns leading the formation before dropping back to fly in the wake of others, which further helps the group save energy during their long-distance journeys.1