Ardeidae in the context of Pelecaniformes

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.

The great blue heron (Ardea herodias) is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North and Central America, as well as far northwestern South America, the Caribbean and the Galápagos Islands. It is occasionally found in the Azores and is a rare vagrant to Europe. An all-white population found in south Florida and the Florida Keys is known as the great white heron. Debate exists about whether these white birds are a color morph of the great blue heron, a subspecies of it, or an entirely separate species.

The cattle egrets (formerly genus Bubulcus) are a cosmopolitan clade of herons (family Ardeidae) in the genus Ardea found in the tropics, subtropics, warm temperate, and increasingly in cooler temperate zones. As currently treated, the clade contains two species, the western cattle egret and the eastern cattle egret, although some authorities (particularly in the past) regarded them as a single species. Despite the similarities in plumage to the egrets of the genus Egretta, they have recently been found to be genetically embedded within the genus Ardea, and are now included there. Originally native to parts of Asia, Africa, and southernmost Europe, the two species have undergone rapid expansion in their distribution and have successfully colonised much of the rest of the world in the last century.

They are white birds adorned with buff plumes in the breeding season. They nest in colonies, usually near bodies of water and often with other wading birds. The nest is a platform of sticks in trees or shrubs. Cattle egrets exploit drier and open habitats more than other heron species. Their feeding habitats include seasonally inundated grasslands, pastures, farmlands, wetlands, and rice paddies. They often accompany cattle or other large mammals, catching insect and small vertebrate prey disturbed by these animals. Some populations are migratory and others show postbreeding dispersal.