Spectacled eider - The lined nest is built on tundra close to the sea, and 5–9 eggs are laid. This species dives for crustaceans and molluscs. The winter range is poorly known, but satellite tracking has led to observations of large flocks of the birds about 100 km southwest of St. Lawrence Island in the Bering Sea during March-April. This area has large populations of bivalves in the underlying sediments at depths of about 60 m that the ducks dive to feed on.
King Eider - King Eider winters in arctic and subarctic marine areas, most notably in the Bering Sea, the west coast of Greenland, eastern Canada and northern Norway. It also occurs annually off the northeastern USA, Scotland and Kamchatka. This species dives for benthic invertebrates like crustaceans, polychaete worms, and molluscs, with mussels being a favoured food. Wintering birds can form large flocks on suitable coastal waters, with some flocks exceeding 100,000 birds.