Sea Ducks

Tribe Mergini

Tribe List based on Helm’s “Wildfowl of Europe, Asia and North America” by Sebastien Reeber published by Bloomsbury 2015 ISBN: 978-1-4729-1234-3 with additional South American species not included in that publication from “Coloured Key to the Wildfowl of the World” by Peter Scott updated and published by WWT in 2006 ISBN: 0-900806-35-4

See Also: Diving Ducks Dabbling Ducks Shelducks

The seaducks (Merginae) form a subfamily of the Anatidae, which is a group of waterfowl that includes the ducks, geese and swans. Most species within this group spend their winters near coastal marine waters. Many species have developed specialized salt glands to allow them to tolerate salt water, but these are poorly developed in juveniles. Some of the species prefer riverine habitats. All but two of the 20 species in this group occupy habitats in far northern latitudes.

The fish-eating members of this group, such as the mergansers and smew, have serrated edges to their bills to help them grip their prey. These are therefore often known as “sawbills”. Other seaducks forage by diving underwater, taking molluscs or crustaceans from the sea floor.

COMMON EIDER (Somateria mollissima)



A big, lethargic, heavy-bodied duck of northern coastlines. Often seen floating offshore in flocks of up to several thousand birds. Sociable in breeding season also, and often nests in colonies. Eider down, famous for its insulating qualities, is used in large amounts in the nest lining of these ducks, helping to keep the eggs warm in frigid northern climates. In some places, such as Iceland, the down is harvested commercially at coastal “eider farms,” where the wild birds are encouraged to nest in sheltered nooks built for them.



LONG-TAILED DUCK (Clangula hyemalis)


The long-tailed duck is a small, neat sea duck. They have small round heads and steep foreheads. In winter, the male is mainly white with some brownish-black markings. He also has greatly elongated tails feathers – hence the name. Females are browner. In flights, they show all dark wings and white bellies. They do not breed in the UK but protection of their wintering sites is important, because they are vulnerable to oil pollution at sea. A winter visitor and passage migrant to the UK, most common from Northumberland north to northern Scotland.


COMMON GOLDENEYE (Bucephala clangula)


A medium sized diving sea duck. Males look black and white with a greenish black head and a circular white patch in front of the yellow eye. Females are smaller, and are mottled grey with a chocolate brown head (see below). In flight, birds show a large area of white on the inner wing.




SMEW (Mergellus albellus)


The smew is a small compact diving duck with a delicate bill. The male is white with a black mask and a black back, the female is grey with a reddish-brown head and white cheek. In flight, it shows black and white wings. It is a winter visitor in small numbers from Scandinavia and Russia. Sometimes birds move here from Holland and Denmark to escape freezing weather there. Little is known about this bird on its breeding grounds.

Information on individual species taken from Avian Web, The WWT, RSPB and audubon

Pictures by Ken James

See Also: Diving Ducks Dabbling Ducks Shelducks