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a genus of birds of the famuly Anatidae. The bill is long and narrow, with sharp toothlike projections on the edges of the mandibles. The head is crested.
The genus comprises seven species; of these, five are distributed in the northern hemisphere, one in tropical South America, and one on the Auckland Islands. There are four species in the USSR. The common merganser, or goosander (M. merganser), has a body length of about 80 cm and weighs 1.5-2 kg. It lives in the forest zone from the western borders to Kamchatka, in the mountains of Middle Asia, and on Lake Sevan. The red-breasted merganser (M. serrator) weighs 0.8-1.2 kg. It is distributed in the forest-tundra and forest zones. There are a few colonies on the Black Sea and on Lake Sevan. The M. squamatus is rare (Sikhote-Alin Range). The smew (M. albellus) has a body length of up to 50 cm and weighs 0.5-0.8 kg. It is distributed in the forest and forest-steppe zones and in some places in the south as far as the lower reaches of the Dnieper and Volga rivers.
The birds either winter on unfrozen bodies of water near their nesting places or fly south. They settle on rivers and lakes that are abundant in fish; the smew settles primarily on tidal lakes. The Mergus are excellent divers. They nest on the ground, in rock crevices, or in tree hollows. Eight to ten eggs are laid per single nesting, with as many as 15 by the goosander. The birds feed on fish, on water insects, and, more rarely, on mollusks. Their commercial value is small.