Breeding
Common eiders are circumpolar in their range, breeding along the coastline of Alaska, nearly the entire coastline of Hudson Bay and eastern Canada, as well as the northern coast of Maine. They typically nest on islands or the coastline. Nesting habitat varies from open areas or in grasses and weeds to under shrubs and spruce trees. Female common eiders often nest in dense colonies (but also nest individually) and lay an average of 3-5 eggs.
Latin: Somateria mollissima
Average length: M 24", F 22.5"
Average weight: M 4.3 lbs., F 3.3 lbs.
Description
Common eiders are the largest duck found in the northern hemisphere. They are stocky, thick-necked birds that hold their heads below body level during flight. Male common eiders have a primarily white head, neck, chest and back. The breast, belly, sides, rump, tail coverts and tail are black. The crown and forehead have a black cap, while the cheeks are pale green and are used in breeding displays. A white round spot occurs on the black flank just forward of the tail. The head has a distinct sloping profile. The bill is olive-gray, turning yellowish near the facial area, and the legs and feet are grayish-green. Female common eiders are russet-brown to gray. All are heavily barred with dark brown lines on their backs, chests, breasts, sides and flanks. The head has a distinct sloping profile. The bill is olive-gray to olive-yellow and the legs and feet are grayish.
Food Habits
Common eiders feed almost entirely on animal material such as mollusks and crustaceans. In particular, blue mussels are an especially important food source. Common eiders feed by diving, utilizing a range of water depths when foraging.
Population
In North America four subspecies of common eiders are recognized: Pacific, Hudson Bay, Northern and American (Atlantic). In the mid-1970s, the North American population was estimated at 1.5 to 2 million birds. In northeastern North America, the average annual fall flight in the mid-1980s was estimated at 311,000-376,000 birds and the annual number of nesting pairs in the mid-1990s was estimated at 71,000. A general decline has been observed in all North American races. Declines are thought to be connected with a decline in food abundance and quality, but much is still unknown.
Migration and Wintering
Common eiders are difficult to track because most migrate over large water bodies and remote areas. In the east, they winter from Greenland to the Gulf of St. Lawrence and south along the Atlantic Coast to Virginia. In the west, they winter south to southern Alaska.
