Anseriformes in the context of "Fowl"

A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term water bird is especially applied to birds in freshwater ecosystems, although others make no distinction from seabirds that inhabit marine environments. Some water birds (e.g. wading birds) are more terrestrial while others (e.g. waterfowls) are more aquatic, and their adaptations will vary depending on their environment. These adaptations include webbed feet, beaks, and legs adapted to feed in the water, and the ability to dive from the surface or the air to catch prey in water.

The term aquatic bird is sometimes also used in this context. A related term that has a narrower meaning is waterfowl. Some piscivorous birds of prey, such as ospreys, sea eagles, fish eagles, fish owls, and fishing owls, hunt aquatic prey but do not stay in water for long and live predominantly over dry land, and are not considered water birds. The term waterbird is also used in the context of conservation to refer to any birds that inhabit or depend on bodies of water or wetland areas. Examples of this use include the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) and the Wallnau Waterbird Reserve.

The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird. Modern phylogenies place birds in the dinosaur clade Theropoda. According to the current consensus, Aves and a sister group, the order Crocodilia, together are the sole living members of an unranked reptile clade, the Archosauria. Four distinct lineages of bird survived the Cretaceous–Paleogene extinction event 66 million years ago, giving rise to ostriches and relatives (Palaeognathae), waterfowl (Anseriformes), ground-living fowl (Galliformes), and "modern birds" (Neoaves).

Phylogenetically, Aves is usually defined as all descendants of the most recent common ancestor of a specific modern bird species (such as the house sparrow, Passer domesticus), and either Archaeopteryx, or some prehistoric species closer to Neornithes (to avoid the problems caused by the unclear relationships of Archaeopteryx to other theropods). If the latter classification is used then the larger group is termed Avialae. Currently, the relationship between non-avian dinosaurs, Archaeopteryx, and modern birds is still under debate.

Swans are birds of the genus Cygnus within the family Anatidae. The swans' closest relatives include geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae, forming the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae. They are the largest waterfowl and are often among the largest flighted birds in their range.

There are six living and many extinct species of swan; in addition, there is a species known as the coscoroba swan, which is no longer considered one of the true swans. Swans usually mate for life, although separation sometimes occurs, particularly following nesting failure, and if a mate dies, the remaining swan will take up with another. The number of eggs in each clutch ranges from three to eight.

Galliformes /ˌɡælɪˈfɔːrmiːz/, also known as gallinaceous birds or landfowl, is an order of heavy-bodied terrestrial birds that contains about 290 species. The order is divided into five families: Phasianidae (chicken and junglefowls, Old World quails, partridges, pheasants, turkeys, peafowl and grouse), Odontophoridae (New World quails), Numididae (guinea fowl), Cracidae (including chachalacas and curassows), and Megapodiidae (incubator birds like malleefowl and brushturkeys). Galliformes and the semi-aquatic order Anseriformes (waterfowl) are collectively called fowl.

Galliform birds have adapted to most environments except innermost deserts and perpetually icy regions, inhabiting every continent except Antarctica. They are important in their ecosystems as seed dispersers and insectivores/vermivores, and many are skilled ground-dwellers that escape predators by running rather than flying. They are sexually dimorphic, and males of most species are more colorful than the females, with often elaborate courtship behaviors that include strutting, fluffing of tail or head feathers, and vocal sounds. They are mainly non-migratory.

The mallard (/ˈmælɑːrd, ˈmælərd/) or wild duck (Anas platyrhynchos) is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa. It has been introduced to New Zealand, Australia, Peru, Brazil, Uruguay, Argentina, Chile, Colombia, the Falkland Islands, and South Africa. Belonging to the subfamily Anatinae of the waterfowl family Anatidae, mallards live in wetlands, eat water plants and small animals, and are social animals preferring to congregate in groups or flocks of varying sizes.

Males (drakes) have green heads, while the females (hens) have mainly brown-speckled plumage. Both sexes have an area of white-bordered black or iridescent purple or blue feathers called a speculum on their wings; males especially tend to have blue speculum feathers. The mallard is 50–65 cm (20–26 in) long, of which the body makes up around two-thirds the length. The wingspan is 81–98 cm (32–39 in) and the bill is 4.4 to 6.1 cm (1.7 to 2.4 in) long. It is often slightly heavier than most other dabbling ducks, weighing 0.7–1.6 kg (1.5–3.5 lb).

Wading birds, also known in North America as waders, are members of several families of long-legged birds found in semi-aquatic ecosystems. Wading birds are not a monophyletic group and different authors classify different families as wading birds. The classification always includes the families Phoenicopteridae (flamingos), Ciconiidae (storks), Threskiornithidae (ibises and spoonbills), Ardeidae (herons, egrets, and bitterns), and the extralimital families Scopidae (hamerkop) and Balaenicipitidae (shoebill) of Africa. These were once classified together in the order Ciconiiformes based on overall similarity in anatomy and ecology, as well as some molecular data. However recent genomic studies have found that this group to be polyphyletic, with flamingos being more closely related to grebes while ibises, herons, the hamerkop and the shoebill are more closely related to pelicans. As a result of these changes flamingos are placed in their own order Phoenicopteriformes and Ciconiiformes are solely restricted to the storks. The rest of the waders have been reclassified into the order Pelecaniformes.

Other families that may be classified as wading birds include Gruidae (cranes) and Aramidae (limpkin). Unlike the previously mentioned families, cranes and the limpkin were never thought to be closely related to the heron-like birds and have always been classified as members of the order Gruiformes. Sunbitterns, the only member of the family Eurypygidae in the order Eurypygiformes, may also be considered to be a wading bird. In addition, the Anhimidae (screamers) of the order Anseriformes may be classified as wading birds. They are commonly found wading in open marshes and weedy lakes.