The Common Eider (Somateria mollissima) is a large, heavy diving duck of the coast, 50–71 cm long with a wingspan of 80–108 cm and a weight of 1.2–2.8 kg, with a distinctive head profile and a wedge-shaped bill feathered along the sides. The adult male in breeding plumage is boldly patterned: black crown, rump and belly, a pale bill tip, a light green patch on the nape, and an otherwise white body with a pinkish flush on the breast. The female is brown-barred year-round, ranging from greyish-brown to reddish-brown or sandy depending on subspecies, with a white-edged dark wing patch; a complex moulting strategy gives non-breeding (eclipse) plumage a highly variable mix of black, brown and white.
The male's call is a distinctive "aa-ooo", often described as sounding like a surprised human exclamation, while the female's call is more of a chattering note. Common Eiders occur along the whole Swedish coast, most numerous in the Baltic and around Bohuslän, largely resident or short-distance migrants, with many wintering along the coast. They dive for food to depths of 2–10 m, feeding mainly on mussels — chiefly blue mussels — along with snails and crustaceans. Nesting takes place on the ground, often on sheltered islets, and the female plucks down from her own breast to line and cover the eggs, laying 4–6 eggs incubated for 25–28 days; this down, prized for its exceptional insulating quality, has traditionally been collected to fill bedding. The Swedish population is estimated at around 60,000 pairs as of 2018, a steep decline from over 300,000 pairs around the year 2000, likely linked to reduced blue mussel stocks and increased predation, and the species is classified as Vulnerable (VU) as a result.
Read about this species in Swedish →