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BC Conservation Data Centre: Species Summary


Somateria mollissima
Common Eider

 
Scientific Name: Somateria mollissima (Linnaeus, 1758)
English Name: Common Eider
 
Classification / Taxonomy
Scientific Name - Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Classification Level: Species
Species Group: Vertebrate Animal
Species Code: B-COEI
Kingdom Phylum Class Order Family
Animalia Craniata Aves Anseriformes Anatidae
   
Conservation Status / Legal Designation
Global Status: G5 (Apr 2016)
Provincial Status: SNA (Mar 2015)
BC List: Accidental
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status:
SARA Schedule:
General Status Canada: 4 - Secure (2005)
Migratory Bird Convention Act: Y
   
Ecology & Life History
General Description: This is a heavy-bodied duck with a relatively short, stout neck and distinctive long triangular (wedge-shaped) bill and head profile. From fall through early summer, adult males have a black crown, greenish rear of head, dark or yellow bill, black underparts, white upperparts and chest, black tail and area around the tail. From summer to fall, adult males are dark brown to blackish overall, with a pale brown stripe through the, brown breats with white flecking, back feathers white with black edges. Immature males are similar to females but have a white chest. Adult females are dark gray to rusty-brown, with fine black barring that forms lines on the flanks.
Global Reproduction Comments: Nesting in Maine occurs from late April to early July. Nesting in the Beaufort Sea region begins in mid- to late June (Johnson and Herter 1989). Clutch size averages 3-5. Incubation, by the female, lasts 24-30 days. The female relies on endogenous energy reserves during incubation. Eggs hatch mainly mid- to late July (sometimes into August) in the region arctic of Alaska and Canada. Young are led to water soon after hatching, are tended by the female, soon join young of other broods, and are independent at around 60-75 days). Female first breeds at 2-3 years, generally not until at least 3 years old. Females rarely renest if the clutch is lost, unless loss occurs during laying or early incubation.

Common eiders commonly nest in loose aggregations or colonies (usually a few dozen pairs, but up to several thousand pairs in some areas). Females commonly deposit eggs in the nests of other females.

Female common eiders that nested successfully lead their young to water and may be accompanied by nonbreeding females that participate in chick protection. Broods often join to form "crèches" of up to many dozens of young. Once formed, a crèche tends to stay together throughout the brood rearing period, although some of the adult females attending it may depart.
Global Ecology Comments: Predation by herring gull and great black-backed gull causes most nesting failures on islands in Maine, but eider nesting success may be enhanced in nests close to a gull colony (gulls defend area against other avian pradators). Arctic fox is sometimes an important predator on nesters in Alaska. Ravens, raccoons, and mink sometimes destroy nests. Annual survivorship of adult generally is relatively high, with sport hunting likely the major cause of mortality in the Atlantic flyway (Kehoe 1994).
Migration Characteristics:
(Global / Provincial)		 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant: 		Y /
Y /
Y /
na /
Global Migration Comments: Some populations do not migrate, and in other populations migration may be partially facultative, depending on conditions. A nonmigratory population occurs in Hudson Bay, Ontario and Quebec (Bellrose 1980). Part of the female population in Maine is migratory, part is resident on or near breeding area (see Blumton et al. 1988).

Spring migration generally begins in March and extends into April for early nesters and to mid-June in arctic nesters. During June and July, males depart from breeding areas to molt (immatures and nonbreeding females may also undertake such migrations). Fall migration varies regionally but occurs mainly in October and November, though females and young may begin moving toward wintering areas in late August-early September(Johnson and Herter 1989). By mid-December most wintering populations have peaked in numbers.

Populations that nest in different areas (e.g., St. Lawrence Estuary, Gulf of St. Lawrence, and Atlantic coast) share the same wintering range (Krohn et al. 1992).
Habitats:
(Type / Subtype / Dependence)
Global Habitat Comments: Nonbreeding habitat includes rocky seacoasts, bays, and estuaries. Rocks, sandbars, and ice are used as resting sites. In winter in the Gulf of St. Lawrence, eiders concentrated in areas with shallow water reefs and high prey density (Guillemette et al. 1993). Most migration is coastal. Nests are on the ground in grass or brush, usually close to salt water, often on an island or rocky headland or along the shore of a pond or lagoon. Nests often but not always are concealed by plants (forest, shrub, or herbaceous), rocks, logs, driftwood. Often nests are in the same site in successive years. See Blumton et al. (1988) for habitat suitability index model.
Food Habits: Invertivore: Adult, Immature
Global Food Habits Comments: Eats mainly mollusks and crustaceans. Often feeds in fairly shallow waters around submerged ledges and reefs of rocky shores. In winter in the Gulf of St. Lawrence, Quebec, feeds on small blue mussels in kelp beds, on green sea urchins over urchin barrens, and on spider crabs and urchins over AGARUM beds (Guillemette et al. 1992).

Females do not feed during incubation; during initial part of breeding period, uses nutritional reserves accumulated in winter and in staging areas.
Global Phenology:
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: Y
Length(cm)/width(cm)/Weight(g): 61/ / 2218
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: Breeding range extends from Alaska across the Arctic to Labrador and Greenland and south to Maine and New Hampshire; from Iceland, the Faroe Islands, Spitsbergen, and Franz Josef Land south to northern British Isles, northern Europe, and southern Scandinavia; and from Wrangel Island, New Siberian Islands, and northeastern Siberia south to Kamchatka and Commander Islands. Winter range in western North America extends from the ice pack south to the Aleutian Islands and Cook inlet and on the Pacific coast south to Washington and Oregon. Winter range in in eastern North America is in Hudson and James bays and from Labrador south to Long Island (New York). Winter range in the western Palearctic extends from the breeding range south to central Europe; and in eastern Eurasia south to Kamchatka (AOU 1998). In North America, concentrations occur around Cape Cod and Penobscot Bay, Maine (Root 1988). In the early 1990s, USFWS Winter Sea Duck Survey found the highest densities in Maine and Massachusetts (Kehoe 1994).
 
Authors / Contributors
Global Information Author: Hammerson, G.
Last Updated: Feb 01, 2010
Provincial Information Author:
Last Updated:
   
References and Related Literature
American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
Blumton, A. K., R. B. Owen, Jr., and W. B. Krohn. 1988. Habitat suitability index models: American eider (breeding). U.S. Fish Wildl. Serv. Biol. Rep. 82(10.149). 24 pp.
Campbell, R.W., N.K. Dawe, I.McT. Cowan, J.M. Cooper, G. Kaiser, and M.C.E. McNall. 1990. The Birds of British Columbia, Vol. 1. Nonpasserines: Introduction, Loons through Waterfowl. Royal B.C. Mus. in association with Environ. Can., Can. Wildl. Serv. 514pp.
Chapdelaine, G., and P. Brousseau. 1992. Distribution, abundance, and changes of seabird populations of the Gaspe Peninsula, Quebec, 1979-1989. Can. field-Nat. 106:427-434.
Guillemette, M., J. H. Himmelman, and C. Barette. 1993. Habitat selection by common eiders in winter and its interaction with flock size. Can. J. Zool. 71:1259-1266.
Guillemette, M., R. C. Ydenberg, and J. H. Himmelman. 1992. The role of energy intake rate in prey and habitat selection of common eiders SOMATERIA MOLLISSIMA in winter: a risk-sensitive interpretation. J. Anim. Ecol. 61:599-610.
Hoopes, E. M. 1992. Entanglement of common eifders in clam culture nets, Bird Observer 20(5):258-259.
Hyslop, C., and J. Kennedy, editors. 1992. Bird trends: a report on results of national ornithological surveys in Canada. Number 2, Autumn 1992. Migratory Birds Conservation Division, Canadian Wildlife Service, Ottawa, Ontario. 20 pp.
Johnson, S. R. and D. R. Herter. 1989. The Birds of the Beaufort Sea. BP Exploration (Alaska) Inc., Anchorage, Alaska. 372 pp.
Kehoe, F.P. 1996. Trends in sea duck numbers in eastern North America. Bird Trends 5:13-15.
Kehoe, P., compiler and editor. 1994. Status and information needs of sea ducks in the Atlantic Flyway. Prepared by the Ad Hoc Sea Duck Committee. 71+ pp.
Krohn, W. B., P. O. Corr, and A. E. Hutchinson. 1992. Status of the American eider with special reference to northern New England. U.S. Fish and Wildlife Service, Fish and Wildlife Research 12. 12 pp.
Palmer, R. S., editor. 1976. Handbook of North American birds. Vol. 3. Waterfowl (concluded). Eiders, wood ducks,diving ducks, mergansers, stifftails. Yale Univ. Press, New Haven. 560 pp.
Root, T. 1988. Atlas of wintering North American birds: An analysis of Christmas Bird Count data. University of Chicago Press. 336 pp.
Schmutz, J. K., R. J. Robertson, and F. Cooke. 1983. Colonial nesting of the Hudson Bay eider duck. Can. J. Zool. 61:2424-2433.
Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 2010. Species Summary: Somateria mollissima. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Oct 8, 2025).