Genus/Species: Chauna torquata
Based on DNA analysis they are probably most closely related to the Australian magpie goose. They bear no resemblance to true waterfowl, nevertheless, they are closely related and seemingly the surviving relatives of the evolutionary line that led to the present day wildfowl.
They have comparatively small, chicken-like heads and short hooked bills, with moderaltely long, stout , unfeathered legs and large feet. Long toes greatly enhance walking ability. There is scarcely any webbing between toes, but they are capable swimmers.
They are noted for extreme bone pnuematicity, practically all their bones are hollow,making their skeleton extrodinarily light. A layer of air sacs beneath their skin causes their flesh to fell spongy, even in the toes. If the skin is pressed, a crackling noise can be heard, thus they are extremely buoyant. Long broad wings facilitate powerful flight, enabling them to soar comfortably, often using thermals to spiral upwards. Both sexes are armed with long, curved, very sharp carpal spurs, two on each wing, one of which may be 2 inches long.
They are extensively distributed throughout the pampas of Northern Argentina, Uruguay,Southern Brazil and the subtropics of Bolivia and Paraguay. Screamers dwell in extensive open areas,flooded to form marshes and swamps, in addition to open savannas, forests, meadowlands, and lakes.
Mainly diurnal, they are almost entirely herbivorous, feeding mainly of succulent greases, leaves, seeds,flowers, and roots of aquatic plants. Invertebrate prey increases when pairs are rearing chicks.
Breeding pairs are strongly territorial, but gregarious other times of the year. Nests are bulky and untidy and made of weeds, reeds, and sticks, and can be quite large, reising several feet from a watery base situated in shallow water. Eggs are laid at 35-40 hour intervals and are relatively large and dirty white. Clutches range between 2 and 7 eggs. Incubation averages between 42 and 45 days. Brood–rearing is shared by both parents. Screamer chicks resemble gosling chicks with thick yellow-grey down. Capable of flight at 8-10 weeks of age , full independence is achieved in 12 to 14 weeks.
Highly vocal, they are named for their distinctive , far-carrying calls, easily carrying for several miles. The Southern Screamer is the most gregarious of the 3 screamer species and the most numerous.
The Natural History of Waterfowl by Frank S. Todd