How do webbed feet help ducks, geese, and swans swim?

Webbed feet are a primary adaptation for swimming in ducks, geese, and swans, which belong to the order Anseriformes. These feet function as effective paddles that propel the birds through the water.1

The webbing between the front three digits increases the surface area of the foot, which allows the bird to push against the water more efficiently during the power stroke. To maintain efficiency, these birds have evolved the ability to fold their feet during the recovery phase of the stroke, which significantly reduces water resistance as the leg is brought forward.23

While the feet paddle alternately during slow swimming, they often move in unison when the bird is moving at higher speeds or when it is submerged. This specialized anatomy, combined with other adaptations such as waterproof plumage and fat-insulated bodies, enables these waterfowl to navigate aquatic environments with great agility.21