Eider

The eiders are large seaducks in the genus Somateria. The three extant species all breed in the cooler latitudes of the Northern Hemisphere.
The down feathers of eider ducks and some other ducks and geese are used to fill pillows and quilts—they have given the name to the type of quilt known as an eiderdown. The common eider is the source of true eider down. In Iceland and other places where the birds are native, traditional farms cultivate a relationship between the sea birds and the farmers, who collect and clean the down for sale.

Taxonomy

The genus Somateria was introduced in 1819 to accommodate the king eider by the English zoologist William Leach in an appendix to John Ross's account of his voyage to look for the Northwest Passage. The name is derived from Ancient Greek : sōma "body" and : erion "wool", referring to eiderdown.
Steller's eider is in a different genus despite its name.

Species

The genus contains three extant species.
Two undescribed species are known from fossils, one from Middle Oligocene rocks in Kazakhstan and another from the Late Miocene or Early Pliocene of Lee Creek Mine, United States. The former may not actually belong in this genus.

Predation

The American mink is a non-native, invasive predator that has cut eider down production in Iceland by more than half. The Arctic fox is another predator of ground-nesting birds.

Folklore

Since the 12th century, the black-and-white common eider has been known as Saint Cuthbert's ducks in parts of Great Britain.