Pelecaniformes in the context of Sulidae

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.

Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family Ciconiidae, and make up the order Ciconiiformes /sɪˈkoʊni.ɪfɔːrmiːz/. Ciconiiformes previously included a number of other families, such as herons and ibises, but those families have been moved to the order Pelecaniformes.

Storks dwell in many regions and tend to live in drier habitats than the closely related herons, spoonbills and ibises; they also lack the powder down that those groups use to clean off fish slime. Bill-clattering is an important mode of communication at the nest. Many species are migratory. Most storks eat frogs, fish, insects, earthworms, small birds and small mammals. There are 20 living species of storks in six genera.

The hamerkop (Scopus umbretta), also called the umbrette, is a medium-sized bird. It is the only living species in the genus Scopus and the family Scopidae. The species and family was long thought to sit with the Ciconiiformes but is now placed with the Pelecaniformes, and its closest relatives are thought to be the pelicans and the shoebill. The shape of its head with a long bill and crest at the back is reminiscent of a hammer, which has given this species its name after the Afrikaans word for hammerhead. It is a medium-sized waterbird with brown plumage. It is found in mainland Africa, Madagascar and Arabia, living in a wide variety of wetlands, including estuaries, lakesides, fish ponds, riverbanks, and rocky coasts. The hamerkop is a sedentary bird that often shows local movements.

The hamerkop takes a wide range of prey, mostly fish and amphibians, but shrimps, insects and rodents are taken too. Prey is usually hunted in shallow water, either by sight or touch, but the species is adaptable and will take any prey it can. The species is renowned for its enormous nests, several of which are built during the breeding season. Unusually for a wading bird, the nest has an internal nesting chamber where the eggs are laid. Both parents incubate the eggs and raise the chicks.

Balaenicipitidae is a family of birds in the order Pelecaniformes, although it was traditionally placed in Ciconiiformes. The shoebill is the sole extant species and its closest relative is the hamerkop (Scopus umbretta), which belongs to another family. Species from the Ciconiiformes and Balaenicipitidae family have been found in Kenya, Uganda, Tanzania, and parts of East Africa.

It has the following genera: