Sea duck
A duck (family Anatidae) associated to a greater or lesser extent with a marine rather than a freshwater habitat. Some of these are called 'bay ducks' in North America. The Eider Somateria mollissima is the only example occurring commonly in the British Isles which is marine throughout the year, but a number of others, such as the Scaup Aythya marila, the Long-tailed Duck Clangua hyemalis and the scoters (genus Melanitta) spend the winter mainly on the sea. The Shelduck Tadorna tadorna and the Wigeon Anas penelope, although much associated with coasts, are more characteristic of estuary or saltmarsh habitats than the sea itself and so would not normally be called 'sea ducks'.From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver