Duck, a name given to any member of the family Anatidae, included under the order Anseres or goose-like birds. The prominent characteristics of the family are very familiar: the short webbed feet, with a small hind-toe which does not reach the ground; the netted scales in front of the lower leg; the bill, about as long as the head, straight or slightly curved, rounded at the tip, and bearing the nostrils towards the broad root. There are over fifty species, which have a wide distribution, especially in the northern hemisphere. They are characteristically aquatic birds, swimming with much agility, diving comparatively little, preferring to grub in the shallows for water-plants, worms, and small animals. The waddling, awkward walk is well known in its exaggerated condition in the domesticated duck. Great flocks are often seen in migratory flight to and from their northern homes. The males (drakes) are in winter and spring markedly distinguished from the females, whose plumage is less handsome. In summer, however, the males generally resemble the females.
The most important genus is Anas, which includes the Common Wild Duck (A. boschas), with its domesticated form (A. domestica), and numerous other species. The Mallard or Wild Duck is very widely distributed from Britain to Japan, and also occurs in North America as far south as Florida and the West Indies. They abound in Britain, though ousted from some parts by increased drainage of marshes. Their food is very varied, from seeds and roots to worms and frogs. They are often seen, with submerged head and upturned tail, grubbing in the mud by the loch side. Along with other 'wild ducks,' they breed in Britain, sometimes near the lakes or rivers which they frequent, sometimes in more elevated moorland districts. The parents often bring their very young brood to the lower waters, by swimming down the streams when swollen by rain, and it is interesting to see the little creatures hurried on, without injury, by the current, and passing along narrow rapids and over waterfalls of considerable height, much as pieces of cork might do, and with as little apparent injury. The nest is composed of grass, intermixed and lined with down, and the eggs are usually nine to twelve in number. The female shows marked parental care and affection for her brood.
The male (drake) of the common duck has the four middle tail-feathers recurved. The deep emerald green of the head and upper part of the neck, the white collar which separates the green from the dark chestnut of the lower part of the neck, and the deep blue iridescent speculum of the wing are marked characteristics of this beautiful bird. The plumage exhibits greater brightness of colours in the wild than in the domestic variety. At the close of the breeding season, the male of the wild duck assumes for a time a plumage more sober, and resembling that of the female; but before winter recovers the splendid plumage proper to his sex.
The Domestic Duck.—According to Mr Darwin and most naturalists, the various breeds of domestic duck are all descended from the wild species above described. In domestication the excellence of the plumage and the elegance of the carriage are lost in a few generations, and more momentous changes follow in consequence of altered nutrition and the like, and largely from the decreased use of the wings and increased use of the legs. The size also increases. It is well known that the nest-building instinct has been unlearned, and even the brooding impulses are usually degenerate. Darwin distinguishes four breeds: the Common Domestic Duck, the Hook-billed Duck, the Call-duck, and the Penguin Duck. Of the first, several sub-breeds are well known—e.g. the Aylesbury—large and white; the Rouen—large, and coloured like the wild duck; the tufted ducks—with top-knots of downy feathers; the black Labradors. 'The duck was unknown to the ancient Egyptians, to the Jews of the Old Testament, and to the Greeks of the Homeric period,' but was kept eighteen centuries ago in Roman poultry-yards. See Darwin's Variation of Animals and Plants under Domestication (1868). For ducks as egg-producers, see POULTRY.
There are many other European wild ducks—e.g. the small A. crecca, extending to North Africa; A. acuta, also found in North America; A. strepera, a distinctly north European form; A. querquedula, from middle and south Europe to Central Asia; A. penelope, in north Europe and Asia. Some closely related genera may be noted. The beautiful North American Aix sponsa is often brought to Europe; the Spoon-billed Ducks (Spatula clypeata, &c.), occurring in the temperate zones of both hemispheres, have markedly elongated bills; the Musk-duck (Cairina moschata), from Brazil and Paraguay, sometimes domesticated, is remarkable for the musk-like smell of the male preen-gland. Less nearly related to the true ducks are the Geese (see GOOSE), Swans (q.v.), Eiders (q.v.), and the stiff-tailed ducks, such as the wide-headed Erimaturia bucocephala, rather like a diver in flight and habit.
Many wild ducks are shot for the market; the plumage is also used for decorative purposes. The uses of the domesticated variety are well known. See also TEAL, CANVAS-BACK, WILDFOWL.