DUCK, the English name for birds forming five of the eleven sub-families of the family Anatidae. Technically, duck is re stricted to the female, the male being called "drake," and, in one species, "mallard." Ducks comprise: (1) the Anatinae or fresh-water ducks; (2) the Fuligulinae or sea-ducks (see EIDER; POCHARD ; SCAUP; SCOTER) ; (3) the Erismaturinae or spiny-tailed ducks; (4) the Merganettinae or torrent ducks; (5) the Merginae or mergansers (q.v.).
The Anatinae are the typical group and the only ones here considered. The mallard (Anas platyrhynchos) is the most plen tiful and best-known species, and is the origin of the domestic breeds of Europe and U.S.A. It inhabits the Northern Hemi sphere, reaching Panama, Egypt and N.W. India in winter, and the Arctic Circle in summer. The nest may be on the ground or in a hole in a tree; 9 to II pale green eggs are laid on a lining of down which the mother pulls from her breast. As soon as the young hatch out, the mother takes them to the nearest piece of water. The male may guard the nest before hatching, but takes no interest in the brood and, indeed, is incapable of rendering active assistance by reason of an additional moult that deprives him of power of flight until the autumn. In hard weather, the ducks resort to tidal waters. For the domestic breeds of duck, see POULTRY AND POULTRY FARMING. It is an interesting point that, whereas the male wild duck is monogamous, the domesticated drake is polygamous.
Numerous allied species occur in various parts of the world, in some of which, e.g., A. obscura of America, there is little difference in plumage between the sexes. Among other genera are the groups represented by the shoveller (q.v.), garganey (q.v.), gadwall (q.v.), teal (q.v.), pintail, and widgeon (q.v.). The genus Aix includes the beautiful American wood-duck (A. sponsa) and the mandarin duck (A. galericulata) from East Asia. The sheldrakes (q.v.), the musk-duck (Cairina) of South America, and the tropical tree-ducks (Dendrocygna) are other groups.