Common Eider

Common Eider male. Photo: Carsten Egevang.
Common Eider male.  Photo: Carsten Egevang.
Common Eider female on the nest. Photo: Lars Maltha Rasmussen.
Common Eider female on the nest. Photo: Lars Maltha Rasmussen.
Common Eider female guiding young. Photo: Lars Maltha Rasmussen.
Common Eider female guiding young. Photo: Lars Maltha Rasmussen.

Somateria mollissima

By Flemming Merkel and Lars Maltha Rasmussen

Appearance

Common Eider is a sea duck attached to the coastal environment. Wingspan: 95-105 cm, length: 60-70 cm. Male: whote back and breast. Black calotte, abdomen and flight feathers. Green in the neck. Young male: black with white patches.

Food

Mainly mussels and clams, but also other benthic fauna as craps and worms.

Breeding

Females breed usually first time as 3 years old. In some areas they mate already in autumn and winter, but some mate late spring. The pair stays together until hatching.

Eiders usually arrive at the breeding sites during May, depending on the site and the weather. Females usually return to their birthplace and often they nest very close to the old nest. Breeding sites are typically on small island, protected from foxes. When females go to shore on shore to choose for a nesting place, the male follow closely. The nest is a shallow scrape in the soil, and the nest is isolated with down picked from the females’ breast feathers, when the first egg is laid.

Clutch size is usually 3-4 eggs. Hatching period is 24-26 days, during which the female only leaves the nest to drink where by she can loose up to 45% of her weight.

The eggs hatches simultaneously within 24 hours. When the pullus have dried after another 24 hours the female will lead them to the water. Often the young are guarded by a number of "aunts" i.e. non-breeding females. Family flocks may build up to 150 young and 10 females or more. Large flocks may split again. The ducklings area becoming independent of 55-60 days and can fly after 65-75 days.

Female and young: Brownish with dark watering. Ung han: Sort med hvide partier. Hun og ungfugl: Brunlig med mørk vatring. Down young: Blackish brown.

Distribution

Map showing the distribution of Common Eider in Greeland, with maximum sizes of colonies. Data: GINR and NERI. Click to enlarge.
Map shoeing distribution of Common Eider in Greeland, with maximum sizes of colonies. Data: GINR and NERI. Click to enlarge.
Common Eiders Distribution and migration routes in Greenland and Eastern Canada. Common Eiders breed along the coast inside the dotted area. Data: NERI.
Common Eiders Distribution and migration routes in Greenland and Eastern Canada. Common Eiders breed along the coast inside the dotted area. Data: NERI.

Common Eider is a widely distributed breeding bird in all of West Greenland, with the largest concentrations in North West Greenland. The Common Eider is also distributed as a breeding bird in Northeast and Southeast Greenland. Breeding birds belong to the subspecies borealis, distributed also in eastern Canada, Iceland, Svalbard and Franz Josef Land. They breed in areas were the ice is not blocking the coast, usually on inlets, not easily assessable to foxes.

Winter distribution and migration

Common Eider is mainly sedentary in Greenland and migrates over short distances, as ice is spreading during winter. It is assumed, that the entire west Greenlandic population moult and winter in the "open water area" in West Greenland. The northern population is assumed to winter in the northern part of the open water area. The far majority of wintering Common Eiders in West Greenland breeds in Arctic Canada (see the map). From mid April breeding birds start to return to the breeding ground. A number of non-breeders stay in West Greenland during the summer.

The total number of common Eider wintering in the open water area in West Greenland was estimated to around 500.000 birds in 1999, and another 150.000 eiders winter at the coast of Newfoundland and Quebeq. Common Eiders from North East Greenland winter at Iceland ad maybe around Tasiilaq.

There is no historical information that the distribution in West Greenland has changed significantly from the present.

Updated 02.09.2016