Waterfowl

Anatidae is the biological family that includes the ducks and most duck-like waterfowl, such as geese and swans. These are birds that are modified for swimming, floating on the water surface, and in some cases diving in at least shallow water.

They have webbed feet and bills which are flattened to a greater or lesser extent. Their feathers are excellent at shedding water due to special oils. Anatidae are remarkable for being one of the few families of birds that possess a penis; they are adapted for copulation on the water only and care must be taken when breeding ducks or geese that a pool is provided for this purpose as attempts to copulate on dry land will often lead to injury of the drake's penis. Duck, eider and goose feathers and down have long been popular for bedspreads, pillows, sleeping bags and coats. The members of this family also have long been used for food.

While the status of the Anatidae as a family is straightforward, and there is little debate about which species properly belong to it, the relationships of the different tribes and subfamilies within it are poorly understood. The listing in the box at right should be regarded simply one of several possible ways of organising the many species within the Anatidae.

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