Anseriform

anseriform, any of more than 160 species constituting the bird order Anseriformes, which comprises the ducks, geese, and swans (family Anatidae) and the screamers (the three species of family Anhimidae). Anatidae comprises about 147 species of medium to large birds, usually associated with freshwater or marine habitats. This family is known collectively as waterfowl (in the United States) or wildfowl (in Europe). The three species of screamers are quite different from waterfowl in general appearance. They are moderately long-legged birds about the size of a turkey, with chickenlike beaks and exceptionally large feet.

Anseriforms are of interest for various reasons. Not only do their mass migrations symbolize the change of seasons to peoples in temperate areas of the world but their annual voyages have long been studied by ornithologists to determine the mechanisms that make these navigational and metabolic feats possible. To the sport hunter many ducks and geese are challenging and worthwhile quarry; domesticated members of the order are reared for meat and feathers, but to the farmer other species are considered pests and crop spoilers. Both domestic and wild anseriforms are occasionally reservoirs of disease. The conservationist views them as biological indicators of the quality of wetlands and, like those habitats, in need of attention.