Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups. These are birds that can swim, float on the water surface, and in some cases dive in at least shallow water. (The Magpie Goose is no longer[when?] considered to be part of the Anatidae, but is placed in its own family Anseranatidae.) The family contains around 146 species in 40 genera. They are generally herbivorous, and are monogamous breeders. A number of species undertake annual migrations. A few species have been domesticated for agriculture, and many others are hunted for food and recreation. Five species have become extinct since 1600, and many more are threatened with extinction.
enera
Subfamily: Dendrocygninae (One pantropical genus, of distinctive long-legged goose-like birds)
Dendrocygna, whistling ducks (9 living species)
Subfamily: Thalassorninae (One genus in Africa, most closely related to the subfamily Dendrocygninae, though also showing convergent similarities to the subfamily Oxyurinae)
Thalassornis, White-backed Duck
Subfamily: Anserinae, swans and geese (Three to seven extant genera with 25–30 living species, mainly cool temperate Northern Hemisphere but also some Southern Hemisphere species, with the swans in one genus [two genera in some treatments], and the geese in three genera [two genera in some treatments]. Some other species are sometimes placed herein, but seem somewhat more distinct [see below])
Cygnus, true swans (7 species, 4 sometimes separated in Olor)
Anser, grey geese (7 species)
Chen, white geese (3 species, sometimes included in Anser)
Branta, black geese (8 living species)
Subfamily: Stictonettinae (One genus in Australia, formerly included in the Oxyurinae, but with anatomy suggesting a distinct ancient lineage perhaps closest to the Anserinae, especially the Cape Barren Goose)
Stictonetta, Freckled Duck
Subfamily: Plectropterinae (One genus in Africa, formerly included in the "perching ducks", but closer to the Tadorninae)
Plectropterus, Spur-winged Goose
Subfamily: Tadorninae – shelducks and sheldgeese
Male Common Shelduck
(This group of larger, often semi-terrestrial waterfowl can be seen as intermediate between Anserinae and Anatinae. The 1986 revision[4] has resulted in the inclusion of 10 extant genera with about two dozen living species [one probably extinct] in this subfamily, mostly from the Southern Hemisphere but a few in the Northern Hemisphere, but the affiliations of several presumed tadornine genera has later been questioned[7] and the group in the traditional lineup is likely to be paraphyletic)
Pachyanas, Chatham Island Duck (prehistoric)
Tadorna, shelducks (7 species, one probably extinct) – possibly paraphyletic
Alopochen, Egyptian Goose and Mascarene Shelducks (1 living species, 2 extinct)
Neochen, Orinoco Goose
Chloephaga, sheldgeese (5 species)
Hymenolaimus, Blue Duck
Merganetta, Torrent Duck
Subfamily: Anatinae, dabbling ducks and moa-nalos (The dabbling duck group, of worldwide distribution, were previously restricted to just one or two genera, but had been extended[4] to include 8 extant genera and about 55 living species, including several genera formerly known as the "perching ducks"; mtDNA on the other hand confirms that the genus Anas is over-lumped and casts doubt on the diving duck affiliations of several genera [see below]. The moa-nalos, of which 4 species in 3 genera are known to date, are a peculiar group of flightless, extinct Anatidae from the Hawaiian Islands. Gigantic in size and with massive bills, they were believed to be geese, but have been shown to be actually very closely related to mallard. They evolved filling the ecological niche of turtles, ungulates and other megaherbivores.)
Anas: wigeons, gadwalls, teals, pintails, mallards, shovelers, etc. (40–50 living species, 3 extinct) – paraphyletic
Subfamily: Aythyinae, diving ducks (Some 15 species of diving ducks, of worldwide distribution, in 2–4 genera; The 1986 morphological analysis[4] suggested that the probably extinct Pink-headed Duck of India, previously treated separately in Rhodonessa, should be placed in Netta, but this has been questioned.[9] Furthermore, while morphologically close to dabbling ducks, the mtDNA data indicates that a treatment as distinct subfamily is indeed correct, with the Tadorninae being actually closer to dabbling ducks than the diving ducks are[7])
Netta, Red-crested Pochard and allies (4 species, one probably extinct)
Aythya, pochards, scaups, etc. (12 species)
Subfamily: Merginae, eiders, scoters, sawbills and other sea-ducks
The rare White-winged Duck, a species of unclear affiliation.
Common Goldeneye couple, male on the right.
(There are 9 extant genera and some 20 living species; most of this group occur in the Northern Hemisphere, but a few [mostly extinct] mergansers in the Southern Hemisphere)
Mergus, mergansers (5 living species, one extinct).
Subfamily: Oxyurinae, stiff-tail ducks (A small group of 3–4 genera, 2–3 of them monotypic, with 7–8 living species)
Oxyura, stiff-tailed ducks (5 living species)
Nomonyx, Masked Duck
Biziura, Musk Ducks (1 living species, provisionally placed here)
Heteronetta, Black-headed Duck
Unresolved
The rare White-winged Duck, a species of unclear affiliation.
Wood Duck Aix sponsa
The largest degree of uncertainty concerns whether a number of genera are closer to the shelducks or to the dabbling ducks. See also the monotypic subfamilies above, and the "perching ducks"
Coscoroba, Coscoroba Swan – Anserinae or same subfamily as Cereopsis?
Cereopsis, Cape Barren Goose – Anserinae, Tadorninae, or own subfamily?
Cnemiornis, New Zealand geese (prehistoric) – as Cereopsis
Malacorhynchus, Pink-eared ducks (1 living species) – Tadorninae, Oxyurinae or Dendrocheninae?
Sarkidiornis, Comb Duck – Tadorninae or closer to dabbling ducks?
Tachyeres, steamer ducks (4 species) – Tadorninae or closer to dabbling ducks?
Cyanochen, Blue-winged Goose – Tadorninae or more distant clade?
Nettapus, pygmy geese (3 species) – Anatinae or part of Southern Hemisphere radiation?
Pteronetta, Hartlaub's Duck – traditionally dabbling ducks, but may be closer to Cyanochen
Cairina, Muscovy Duck and White-winged Duck (2 species) – traditionally dabbling ducks, but may be paraphyletic, with one species in Tadorninae and the other closer to diving ducks
Aix, Mandarin Duck and Wood Duck (2 species) – dabbling ducks or Tadorninae?
Callonetta, Ringed Teal – dabbling ducks or Tadorninae?
Chenonetta, Maned Duck (1 living species) – dabbling ducks or Tadorninae? Includes Euryanas.
Marmaronetta, Marbled Duck – Formerly dabbling ducks; actually a diving duck or a distinct subfamily
Prehistoric species
The Maned Duck is the only living member of the genus Chenonetta
From subfossil bones found on Kauai (Hawaiian Islands), two enigmatic waterfowl are known. The living and assignable prehistoric avifauna of the archipelago contains as Anseriformes Branta geese and their descendants, and the moa-nalos as mentioned above. The following taxa, although certainly new species, cannot be assigned even to subfamily; that Kauai is the oldest of the large Hawaiian Islands, meaning the species may have been evolving in isolation for nearly up to 10 mya (since the Late Miocene), does not help in determining their affinities:
Long-legged "Shelduck", Anatidae sp. et gen. indet.
Talpanas
Similarly, Geochen rhuax from the Big Island of Hawaii, and a gigantic goose-like anatid from Oahu are known only from very incomplete and in the former case much damaged bone fragments. The former has been alleged to be a shelduck, but this was generally dismissed because of the damage to the material and biogeographic considerations. The long-legged Kauai bird, however, hints at the possibility of a former tadornine presence on the archipelago.
