Merginae

Sea ducks
Harlequin duck, Histrionicus histrionicus (male)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Family:	Anatidae
Subfamily:	Merginae
Genera
Chendytes (extinct) Polysticta Somateria Histrionicus Camptorhynchus (extinct) Melanitta Clangula Bucephala Mergellus Lophodytes Mergus

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.

Unlike the Alcidae (auks), the Merginae take on the eclipse plumage during the late summer, and molt into their breeding plumage during the winter.

Species

There are twenty living species in ten extant genera:

• Genus †Chendytes, the diving-geese. These birds became extinct in prehistoric times. They were large, goose-like ducks with reduced wings which were unfit for flying, but could assist in diving as in the great auk. At least one species survived to the Holocene.
  • †Chendytes lawi
• Genus Polysticta
  • Steller's eider (Polysticta stelleri)
• Genus Somateria, the eiders. These are large marine ducks. The drakes have body plumage showing varying amounts of black and white, and distinctive head patterns. Females are brown.
  • Common eider (Somateria mollissima)
  • Spectacled eider (Somateria fischeri)
  • King eider (Somateria spectabilis)
• Genus Histrionicus
  • Harlequin duck (Histrionicus histrionicus)
• Genus †Camptorhynchus
  • †Labrador duck (Camptorhynchus labradorius) (extinct)
• Genus Melanitta, the scoters. These are stocky marine ducks. The drakes are mostly black and have swollen bills. Females are brown.
  • Common scoter (Melanitta nigra)
  • Black scoter or American scoter (Melanitta americana) (sometimes considered a subspecies of M. nigra)
  • Velvet scoter (Melanitta fusca)
  • White-winged scoter (Melanitta deglandi) (sometimes considered a subspecies of M. fusca)
  • Surf scoter (Melanitta perspicillata)
• Genus Clangula
  • Long-tailed duck or oldsquaw (Clangula hyemalis)
• Genus Bucephala, the goldeneyes. These are less marine than some species in this group, and will winter on fresh water. Drakes have white bodies with black backs and distinctive head markings. Females are grey with chestnut heads.
  • Common goldeneye (Bucephala clangula)
  • Barrow's goldeneye (Bucephala islandica)
  • Bufflehead (Bucephala albeola)
• Genus Mergellus (sometimes included in Mergus)
  • Smew (Mergellus albellus)
• Genus Lophodytes (sometimes included in Mergus)
  • Hooded merganser (Lophodytes cucullatus)
• Genus Mergus, the typical mergansers. These are the least marine of this group, only red-breasted and common mergansers being common on the sea. These are large saw-billed ducks which dive for fish.
  • Brazilian merganser (Mergus octosetaceus)
  • †Auckland merganser (Mergus australis)
  • Red-breasted merganser (Mergus serrator)
  • Common merganser or goosander (Mergus merganser)
  • Scaly-sided merganser (Mergus squamatus)

References

Wikimedia Commons has media related to Merginae.