Water fowl

Anatidae Temporal range: Early Oligocene – recent
Black-bellied whistling duck (Dendrocygna autumnalis)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Clade:	Anseres
Superfamily:	Anatoidea
Family:	Anatidae Vigors, 1825
Type species
Anas platyrhynchos Linnaeus, 1758
Extant Genera
Subfamily Dendrocygninae Dendrocygna Subfamily Thalassorninae Thalassornis Subfamily Stictonettinae Stictonetta Subfamily Oxyurinae Biziura Heteronetta Nomonyx Oxyura Subfamily Anatinae Amazonetta Anas Chelychelynechen Lophonetta Nettapus Ptaiochen Speculanas and possibly: Aix Asarcornis Cairina Callonetta Chenonetta (or in Tadorninae) Pteronetta Rhodonessa Subfamily Tadorninae Alopochen Chloephaga Hymenolaimus Merganetta Neochen Salvadorina Tadorna and possibly: Cyanochen Sarkidiornis (or in Anatinae) Tachyeres Malacorhynchus Subfamily Plectropterinae Plectropterus Subfamily Aythyinae Aythya Marmaronetta Netta Subfamily Merginae Bucephala Clangula Histrionicus Lophodytes Melanitta Mergellus Mergus Polysticta Somateria Subfamily Anserinae Anser Branta Chen Cereopsis Coscoroba Cygnus

The Anatidae are the biological family of birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents. These birds are adapted for swimming, floating on the water surface, and in some cases diving in at least shallow water. The family contains around 146 species in 40 genera. (The magpie goose is no longer considered to be part of the Anatidae, but is placed in its own family Anseranatidae.)

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.

The ducks, geese, and swans are small- to large-sized birds with a broad and elongated general body plan. Diving species vary from this in being rounder. Extant species range in size from the cotton pygmy goose, at as little as 26.5 cm (10.5 in) and 164 g (5.8 oz), to the trumpeter swan, at as much as 183 cm (6 ft) and 17.2 kg (38 lb). The wings are short and pointed, and supported by strong wing muscles that generate rapid beats in flight. They typically have long necks, although this varies in degree between species. The legs are short, strong, and set far to the back of the body (more so in the more aquatic species), and have a leathery feel with a scaly texture. Combined with their body shape, this can make some species awkward on land, but they are stronger walkers than other marine and water birds such as grebes or petrels. They typically have webbed feet, though a few species such as the Nene have secondarily lost their webbing. The bills are made of soft keratin with a thin and sensitive layer of skin on top (which has a leathery feel when touched). For most species, the shape of the bill tends to be more flattened to a greater or lesser extent. These contain serrated lamellae which are particularly well defined in the filter-feeding species.

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Wikipedia