Merganser:

Common name for any of six fish-eating ducks characterized by a slender, compressed bill, hooked at the tip and serrated at the edges. They are seldom hunted for food because of their fishy taste.

Five of the species inhabit the northern hemisphere. Two are widely distributed in Europe and North America. The common merganser, also known as the goosander, ranges from 55 to 68 cm (22 to 27 in) in length. The male is black above, with a dark green, uncrested head, white sides and belly, and a red bill. The female is grey above and white below, with a bright chestnut head and neck and a shaggy crest. The red-breasted merganser is slightly smaller; both sexes have crests. As the name suggests, the male has a dark rusty band, speckled with black, across the breast.

Europe and North America have one small merganser each. The smew is the small merganser of Europe, about 38 cm (15 in) long. The male is white, with black markings on the back, head, and wings. The female has a grey body, chestnut cap, and white cheeks. The hooded merganser of North America is about 43 cm (17 in) in length. The male has a black head with a fan-shaped white crest, outlined in black, with a black back and reddish-brown sides. The female is dull brown and grey, with a smaller crest.

Little is known about two rare species, the Chinese and Brazilian mergansers. A seventh species, now extinct, was confined to the Auckland Islands, New Zealand.

Scientific classification: Mergansers make up the subfamily Merginae of the family Anatidae. The common merganser, or goosander, is classified as Mergus merganser; the red-breasted merganser as Mergus serrator; the smew as Mergellus albellus, and the hooded merganser as Lophocytes cucullatus. The Chinese merganser is classified as Mergus squamatus, and the Brazilian merganser as Mergus octosetaceus. The extinct species native to the Auckland Islands is classified as Mergus australis.