Many large birds such as geese, ducks, and swan fly in well-defined V formations, especially during migrations. It is their method of conserving energy so that they can fly long distances without taking a break. The V formation also helps birds maintain visual contact with one another. As each bird flaps its wings, it creates uplift at the tip of its wing. This reduces the air resistance for the bird flying behind. Thus the bird at the lead position works the hardest to break through the air. Therefore, after some time another bird takes over the position.
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