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 and sea eagles, hunt aquatic prey but do not stay in water for long and lives 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. Types Some examples of water birds are: Seabirds (marine birds, orders Suliformes, Sphenisciformes, Phaethontiformes, and Procellariiformes, family Pelecanidae within Pelecaniformes and families Alcidae, Laridae, and Stercorariidae within Charadriiformes) Shorebirds (waders, order Charadriiformes) Waterfowls (order Anseriformes, i.e. ducks, geese, swans, magpie geese, screamers) Grebes (order Podicipediformes) Loons (order Gaviiformes) Storks (order Ciconiiformes) Pelecaniformes (pelicans, herons, egrets, ibises, etc.) Flamingos (order Phoenicopteriformes) Some members of the order Gruiformes (including cranes and rails, crakes, coots and moorhens) Kingfishers (mainly the water kingfishers, sometimes the river kingfishers, and rarely the tree kingfishers) One family of passerines, the dippers Evolution The evolution of waterbirds is often mainly centered around adaptations to improve feeding techniques. This includes legs that are adapted to diving or wading and webbing between the toes. Many of these adaptations are common between different types of waterbirds. For example, flamingos and ducks share a similar filter-feeding lifestyle, and the shoebill has a similar structure (morphology) to many wading birds. DNA sequence analysis, specifically the mitochondrial gene sequencing, has been used to classify and differentiate the various aquatic birds. This classification is found by a relative apparent synapomorphy analysis (RASA) which highlighted certain branches of genes that classified the domestic duck and fowl,