Screamers are three species of large birds in the family Anhimidae. This family is in the order Anseriformes, which also includes the ducks, geese, and swans, although screamers bear little superficial resemblance to these waterfowl. Screamers are non-migratory birds that inhabit a wide range of aquatic habitats in the tropics of South America, especially marshy places.
Screamers are large birds, with a body length of 28-36 in (71-91 cm), and a heavy body, weighing as much as 10 lb (4.5 kg). The wings are large and rounded, and have two pairs of prominent, sharp spurs at the bend (which is anatomically analogous to the wrist). The spurs are used to attack other screamers intruding on a defended territory, or in defense against predators. The legs and feet are long and strong, and the toes are slightly webbed. The head has a crest at the back, and the beak is small, downward curved, and fowl-like in appearance. Almost all of the bones of screamers are hollow, and their body has numerous air-sacs. Both of these features serve to lighten the weight of these large-bodied birds. The coloration of screamers is typically gray, with some black markings. The sexes are alike in size and coloration.
Screamers are strong but slow fliers, and they often soar. They are semi-aquatic animals, spending much of their time walking about in the vicinity of aquatic habitats, and often on mats of floating vegetation, but not usually in the water itself. They feed on aquatic plants, and sometimes on insects.
True to their name, screamers have very loud, shrill cries that they use to proclaim their breeding territory. Screamers build their nest on the ground, and lay from one to six unspotted eggs. The eggs are incubated by both parents, who also raise the young together. The babies are precocious, and can leave the nest soon after they hatch, following their parents and mostly feeding themselves. Screamers are monogamous, and pair for life.
The horned screamer (Anhima cornuta ) has a 6-in (15 cm) long, forward-hanging, horny projection on its forehead, probably important in species recognition, or in courting displays. This species ranges through much of the South American tropics.
The black-necked or northern screamer (Chauna chavaria ) occurs in Colombia and northern Venezuela. The crested or southern screamer (C. torquata ) occurs in Brazil, Bolivia, northern Argentina, and Paraguay.