The screamers are three South American bird species placed in family Anhimidae. They were thought to be related to the Galliformes because of similar bills, but are more related to ducks (family Anatidae), and most closely related to the magpie goose. The clade is exceptional within the living birds in lacking uncinate processes of ribs. The three species are: The horned screamer (Anhima cornuta); the southern screamer or crested screamer (Chauna torquata); and the northern screamer or black-necked screamer (Chauna chavaria).
The three species occur only in South America, ranging from Colombia to northern Argentina. The horned screamer was once present on the Caribbean island of Trinidad, but is now extirpated from there. They are large, bulky birds, with a small downy head, long legs and large feet which are only partially webbed. They have large spurs on their wings which are used in fights over mates and territorial disputes; these can break off in the breast of other screamers, and are regularly renewed. Unlike ducks, they have a partial moult and are able to fly throughout the year. They live in open areas and marshes with some grass and feed on water plants. One species, the southern screamer, is considered a pest as it raids crops and competes with farm birds.