Any of several species of large diving ducks (in tribes Mergini and Somateriini) that are heavy and round-bodied, with a humped bill that produces a characteristic sloping profile. Eiders are the source of eiderdown, feathers that the hen plucks from her breast to line the nest and insulate her eggs. Eiderdown is used as a warm filling for jackets, pillows, quilts, and sleeping bags. Hens are mottled brown, but drakes (males) are boldly patterned, with a green pigment on the head. Eiders live in the cold far north
Somateria mollissima, which breeds in the northern parts of Europe and America, and lines its nest with fine down (taken from its own body) which is an article of commerce; called also eider duck