Dendrocygninae
Thalassorninae
Anserinae
Stictonettinae
Plectropterinae
Tadorninae
Anatinae
Merginae
Oxyurinae Anatidae is the biological family that includes the ducks and most duck-like waterfowl, such as geese and swan. These are birds that are modified for swimming, floating on the water surface, and in some cases diving in at least shallow water.

They have webbed feet and bills which are flattened to a greater or lesser extent. Their feathers are excellent at shedding water due to special oils. Duck, eider and goose feathers and down have long been popular for bedspreads, pillows, sleeping bags and coats. The members of this family also have long been used for food.

While the status of the Anatidae as a family is straightforward, and there is little debate about which species properly belong to it, the relationships of the different tribes and subfamilies within it are poorly understood. The listing in the box at right should be regarded simply one of several possible ways of organising the many species within the Anatidae.

Classification

Previously divided into six subfamilies, recent anatomical studies by Livezey (1986; A phylogenetic analysis of recent Anseriform genera, Auk 103: 737-754) showed that the Anatidae are better treated in nine subfamilies. This classification has been followed by Madge & Burn, Wildfowl (1988):

Dendrocygninae: whistling ducks

• One pantropical genus, of distinctive long-legged goose-like birds:
  • Dendrocygna (whistling ducks, 9 species)

Thalassorninae: White-backed Duck

• One genus in Africa, most closely related to the subfamily Dendrocygninae, though also showing convergent similarities to the subfamily Oxyurinae:
  • Thalassornis (White-backed Duck, one species)

Anserinae: swans and geese

• Five to seven genera with 23 species, mainly cool temperate Northern Hemisphere but also some Southern Hemisphere species, with the swans in two genera (three genera in some treatments), and the geese in three genera (four genera in some treatments):
  • Coscoroba (Coscoroba Swan)
  • Cygnus (swans, 6 species, 3 sometimes separated in Olor)
  • Anser (grey geese, 10 species, 3 sometimes separated in Chen)
  • Branta (black geese, 5 species)
  • Cereopsis (Cape Barren Goose, sometimes transferred to Tadorninae)

Stictonettinae: Freckled Duck

• One genus in Australia, formerly included in the Oxyurinae, but with anatomy suggesting a distinct ancient lineage perhaps closest to the Anserinae:
  • Stictonetta (Freckled Duck, one species)

Plectropterinae: Spur-winged Goose

• One genus in Africa, formerly included in the 'perching ducks', but closer to the Tadorninae:
  • Plectropterus (Spur-winged Goose)

Tadorninae: shelducks, sheldgeese and steamer-ducks

• This group of larger, often semi-terrestrial waterfowl can be seen as intermediate between Anserinae and Anatinae. Recent revision has resulted in the inclusion of 10 genera with 23 species (one extinct) in this subfamily, mostly from the Southern Hemisphere but a few in the Northern Hemisphere:
  • Sarkidiornis (Comb Duck)
  • Tadorna (shelducks, 7 species, one probably extinct)
  • Hymenolaimus (Pink-eared Duck)
  • Alopochen (Egyptian Goose)
  • Neochen (Orinoco Goose)
  • Chloephaga (sheldgeese , 5 species)
  • Cyanochen (Blue-winged Goose)
  • Hymenolaimus (Blue Duck)
  • Merganetta (Torrent Duck)
  • Tachyeres (steamer ducks , 4 species)

Anatinae: dabbling and diving ducks

• The dabbling duck group, of worldwide distribution, were previously restricted to just one or two genera, but has now been extended to include 10 genera and about 55 species, including several genera formerly known as the "perching ducks":
  • Pteronetta (Hartlaub's Duck )
  • Cairina (Muscovy Duck and White-winged Wood Duck, 2 species)
  • Aix (Mandarin Duck and Wood Duck, 2 species)
  • Lophonetta (Crested Duck )
  • Nettapus (pygmy geese, 3 species)
  • Salvadorina (Salvadori's Duck)
  • Anas (wigeons, gadwalls, teals, pintails, mallards, shovelers, etc, 40-45 species)
  • Callonetta (Ringed Teal)
  • Chenonetta (Maned Duck)
  • Amazonetta (Brazilian Duck)
• The 16 species of diving ducks, of worldwide distribution, in 3 genera; Marmaronetta was formerly included with the dabbling ducks but is now treated here, and genetic analysis of the extinct Pink-headed Duck of India, previously treated separately in Rhodonessa, has shown that it is better placed in Netta:
  • Marmaronetta (Marbled Duck)
  • Netta (Red-crested Pochard and allies, 4 species, one recently extinct)
  • Aythya (pochards, scaups, etc, 12 species, one probably extinct)

Merginae: eiders, scoters, sawbills and other sea-ducks

• There are 10 genera and 20 species (two extinct); most of this group occur in the Northern Hemisphere, but two Mergus in the Southern Hemisphere:
  • Polysticta (Steller's Eider)
  • Somateria (eiders, 3 species)
  • Histrionicus (Harlequin Duck)
  • Camptorhynchus (Labrador Duck, extinct)
  • Melanitta (scoters, 3 species)
  • Clangula (Long-tailed Duck)
  • Bucephala (goldeneyes, 3 species)
  • Mergellus (Smew)
  • Lophodytes (Hooded Merganser)
  • Mergus (mergansers, 5 species, one extinct).

Oxyurinae: stiff-tail ducks

• A small group of 4 genera, 3 of them monotypic, with 8 species:
  • Oxyura (stiff-tailed ducks, 6 species)
  • Biziura (Musk Duck)
  • Heteronetta (Black-headed Duck)