i'der, Duck a species of duck found both in America and Europe. Its favorite haunts are solitary rocky shores and islands. The eider duck is about twice the size of the common duck. The male is mostly black, but has a white back and head, with a black crown. The female is reddish drab, spotted with black, and has two white bands on the wings. The nests are usually formed of drift grass and dry seaweed and are lined with a large quantity of down, which the female plucks from her own breast. One female generally furnishes about a half-pound of down. This down, from its superior warmth, lightness and elasticity, is in great demand for beds and coverlets; and the districts in Norway and Iceland where these birds abound are guarded with the greatest vigilance as a most valuable property. As found in commerce, this down is in balls of the size of a man's fist. It is so fine and elastic that five pounds of the best quality are sufficient for a whole bed.