Their feathers are excellent at shedding water due to special oils. These contain serrated lamellae which are particularly well defined in the filter-feeding species. For most species, the shape of the bill tends to be more flattened to a greater or lesser extent. The bills are made of soft keratin with a thin and sensitive layer of skin on top (which has a leathery feel when touched). They typically have webbed feet, though a few species such as the Nene have secondarily lost their webbing. 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. 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. They typically have long necks, although this varies in degree between species. The wings are short and pointed, and supported by strong wing muscles that generate rapid beats in flight. The largest anatid ever known is the extinct flightless Garganornis ballmanni at 22 kg (49 lb). 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). Diving species vary from this in being rounder. The ducks, geese, and swans are small- to large-sized birds with a broad and elongated general body plan. Landing mallard drake Description and ecology Five species have become extinct since 1600, and many more are threatened with extinction. A few species have been domesticated for agriculture, and many others are hunted for food and recreation. A number of species undertake annual migrations. They are generally herbivorous, and are monogamous breeders. (The magpie goose is no longer considered to be part of the Anatidae and is now placed in its own family, Anseranatidae.) The family contains around 174 species in 43 genera. These birds are adapted for swimming, floating on the water surface, and in some cases diving in at least shallow water. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. The Anatidae are the biological family of water birds that includes ducks, geese, and swans.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |