Why do geese fly in a V formation?

Geese and many other flocking birds use a V formation because it is energetically efficient. Each bird flying behind another gains from the upwash of air created by the bird in front, which reduces drag and can make long flights easier. The leader does the most work, so birds may rotate positions during the journey. The formation also helps birds stay coordinated and maintain visual contact. It is a practical example of how aerodynamics shapes animal behavior.