欧绒鸭种

欧绒鸭（学名：somateria mollissima，英语：common eider）是一种体型较大（50—71厘米（20—28英寸））的秋沙鸭，主要分布在欧洲、北美洲、东西伯利亚的北侧海岸上。欧绒鸭仔主要在北极以及其他靠近北方的地区繁殖，但会在冬季往南部温带地区迁徙，迁徙时会形成大片的鸟群。其飞行速度可达113公里每小时。

The common eider (pronounced) (Somateria mollissima), also called St. Cuthbert's duck or Cuddy's duck, is a large (50–71 cm (20–28 in) in body length) sea-duck that is distributed over the northern coasts of Europe, North America and eastern Siberia. It breeds in Arctic and some northern temperate regions, but winters somewhat farther south in temperate zones, when it can form large flocks on coastal waters. It can fly at speeds up to 113 km/h (70 mph).

The eider's nest is built close to the sea and is lined with eiderdown, plucked from the female's breast. This soft and warm lining has long been harvested for filling pillows and quilts, but in more recent years has been largely replaced by down from domestic farm-geese and synthetic alternatives. Although eiderdown pillows or quilts are now a rarity, typically being marketed as luxury goods, eiderdown harvesting continues and is sustainable, as it can be done after the ducklings leave the nest with no harm to the birds.

Taxonomy

The common eider was formally named by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae. He placed it with all the other ducks in the genus Anas and coined the binomial name Anas mollissima. It is now placed with two other species in the genus Somateria that was introduced in 1819 by the English zoologist William Leach. The genus name is derived from Ancient Greek σῶμα sōma 'body' (stem somat-) and ἔριον erion 'wool'. The specific mollissimus is Latin, meaning 'very soft'. Both parts of the name refer to its down feathers.

Subspecies

Six subspecies are recognised:

S. m. v-nigrum Bonaparte & Gray, GR, 1855 – breeds in northeast Asia and Alaska; winters in the Bering Sea and the Aleutian Islands

S. m. borealis (Brehm, CL, 1824) – breeds in northeast Canada, Greenland and Iceland; winters in the north Atlantic

S. m. sedentaria Snyder, 1941 – breeds in Hudson Bay and James Bay (Canada)

Description

The common eider is the largest of the four eider species, measuring 50 to 71 cm (19+1⁄2 to 28 in) in length, weighs 0.81 to 3.04 kg (1 lb 12+1⁄2 oz to 6 lb 11 oz) and spans 80–110 cm (31–43 in) across the wings. The average weight of 22 males in the North Atlantic was 2.21 kg (4 lb 14 oz) while 32 females weighed an average of 1.92 kg (4 lb 3+1⁄2 oz). It is distinguished by its bulky shape and large, wedge-shaped bill. The male is distinct, with its black and white plumage and green nape. The female is a brown bird, but can still be readily distinguished from all ducks, except other eider species, on the basis of size and head shape. The drake's display call is a strange almost human-like "ah-ooo", while the duck utters hoarse quacks. The species is often readily approachable.

Ecology

This species dives for crustaceans and molluscs, with mussels being a favoured food. The eider will eat mussels by swallowing them whole; the shells are then crushed in their gizzard and excreted. When eating a crab, the eider will remove all of its claws and legs, and then eat the body in a similar fashion.

It is abundant, with populations of about 1.5–2 million birds in both North America and Europe, and also large but unknown numbers in eastern Siberia (HBW). Some populations are small and declining, notably the isolated Crimean population in the Black Sea is declining and of conservation concern, with only around 700–1,100 pairs.

A particularly famous colony of eiders lives on the Farne Islands in Northumberland, England. About 1,000 pairs still nest there every year.

Social behaviour

Eiders are colonial breeders. They nest on coastal islands in colonies ranging in size of less than 100 to upwards of 15,000 individuals. Female eiders frequently exhibit a high degree of natal philopatry, where they return to breed on the same island where they were hatched. This can lead to a high degree of relatedness between individuals nesting on the same island, as well as the development of kin-based female social structures. This relatedness has likely played a role in the evolution of co-operative breeding behaviours amongst eiders. Examples of these behaviours include laying eggs in the nests of related individuals and crèching, where female eiders team up and share the work of rearing ducklings.