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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