Re degli edredoni

Identificazione

The king eider is a large sea duck, measuring 50–70 cm (20–28 in) in length with a wingspan of 86–102 cm (34–40 in). Males are, on average, heavier than females, with a mean weight of 1.668 kg (3.68 lb) for males and 1.567 kg (3.45 lb) for females. An individual bird's mass can vary considerably from season to season—from as little as 0.9 kg (2.0 lb) to as much as 2.2 kg (4.9 lb). Like all eiders, the species is sexually dimorphic; the male is slightly larger and, in breeding plumage, much more colourful than the female. The male is unmistakable with its mostly black body, buff-tinged white breast and multicoloured head. The head, nape and neck are a pale bluish grey. The cheek is pale green. The bill, separated from the face by a thin black line, is red with a white nail and a large, distinctive yellow knob. Some tertials are curved up and form "spurs" along the back.<p>The female (occasionally colloquially referred to as a "queen eider") is a warm brown colour overall, slightly paler on the head and neck. The feathers on her upperparts and flanks are marked with blackish chevrons, while those on her neck and head bear fine black streaks. She has a buffy spot at the base of her bill and a buffy eye ring which extends into a downward curving stripe behind her eye. Her bill is variously described as black or grey, and her legs and feet are greenish grey.<p>Juvenile birds are greyish brown. Late in their first autumn, young males moult into a darker plumage, with white on the breast and rump; it takes them three years to achieve full adult plumage.

Tassonomia

When he first described the king eider in 1758, in the 10th edition of his opus Systema Naturae, Carl Linnaeus assigned it to the genus Anas, along with the rest of the ducks. In 1819, William Elford Leach moved it and the other large eiders to the genus Somateria, where it has remained since. It is very closely related to the other members of its genus, and is known to hybridise with the common eider. Despite its very large range, it is monotypic.<p>The genus name Somateria is a combination of the Greek words sōma, meaning "body", and erion, meaning "wool"; the combination (i.e. "wooly body") is a reference to the eider's famously thick, soft down. The specific name spectabilis is Latin for "showy", "remarkable" or "worth seeing", a reference to the handsomeness of the adult male's plumage. The bird's common name, king eider, is a direct translation of its Icelandic name. It is called "king" because of the orange, crown-like knob above the male's bill; the male's multicoloured plumage also suggests royal robes. "Eider" is a Dutch, German or Swedish word derived from the Icelandic word æður (meaning eider), itself derived from the Old Norse æthr.

Nome scientifico

Somateria spectabilis

Autorità

(Linnaeus, 1758)

Ordine

Anseriformi

Famiglia

Anatidae

Genere

Somateria

Areale e habitat

The king eider is circumpolar, found throughout the Arctic. It breeds on the Arctic coast of Alaska, Canada, Greenland, Svalbard and Russia, using a variety of tundra habitats. It winters in arctic and subarctic marine areas, most notably in the Bering Sea, the west coast of Greenland, eastern Canada and northern Norway. Wintering birds can form large flocks on suitable coastal waters, with some flocks exceeding 100,000 birds. It also occurs annually off the northeastern United States, Scotland and Kamchatka.

Areale riproduttivo

NA, PAL : coastal n, c Greenland, Svalbard (n of Norway), Russia from e of the White Sea to Chukotka (ne Russia); Arctic Coastal Plain of Alaska, n slope of Canada and associated Arctic is.

Areale non riproduttivo

to Kamchatka (se Russia) and Aleutian Is.; Newfoundland (se Canada), s Greenland, Iceland, and n Norway

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione