Southern Screamer

The southern screamer is one of the largest birds of southern South America, measuring 83 to 90 cm. It is a stout waterfowl with a small head, a grey, chicken-like bill, a grey head and upperparts and a velvety black collar. It lives in tropical and subtropical wetlands from eastern Bolivia south into Argentina as far as Buenos Aires Province, and east through Paraguay into southwestern Brazil and Uruguay. It grazes like a goose on the leaves, stems and seeds of aquatic plants, in flocks of up to about 100 outside the breeding season. Pairs form long-term bonds, sometimes for life, courting with mutual preening and duet calling.

About the southern screamer

The southern screamer is a large, goose-like wetland bird of southeastern South America. It belongs to the screamer family, Anhimidae, within the waterfowl order Anseriformes, which also holds ducks and geese. It lives in marshes, lakes and flooded meadows from Bolivia and Paraguay to Argentina, Uruguay and southwestern Brazil.

Its scientific name is Chauna torquata. There are only three screamers in the world. The southern screamer shares its genus with the northern screamer, and the horned screamer is the only other member of the family. The species has no recognized subspecies. Though screamers look nothing like a typical duck, they are relatives of birds such as the white-faced whistling duck and the ruddy duck.

This is one of the largest birds of southern South America, 83–90 cm (33–35 in) long. Weight has been recorded from just one female, at 4.4 kg (9.7 lb). The body is stout and heavy, while the head looks oddly small, with a short, downcurved, chicken-like bill and patches of pink skin around the eye and bill base. A thin grey crest sticks out backward from the crown.

The plumage is mostly soft grey. Around the neck sits a two-part collar: a narrow band of tiny white feathers that looks almost bald, and below it a velvety black ring. The breast and flanks are pale grey with faint white mottling, the belly is pale grey to white, and the wings and tail are dusky. The long legs and feet are rosy pink. Males and females look alike, though males average slightly longer wings, about 550 mm (21.6 in) against 531 mm (20.9 in).

The screamer's most surprising features are hidden. Each wing carries two sharp spurs at the bend, which both sexes use in territorial disputes and to defend themselves. Under the skin lies a layer of small air sacs, which likely make the bird lighter for swimming and flying, and its skeleton is considered the most air-filled, or pneumatic, of any bird. Young screamers are covered in yellow down and stand about 15–20 cm (6–8 in) tall on the same thick pink legs as the adults.

Behavior and diet

Southern screamers are active by day, or diurnal. They swim well but prefer to stay on the ground, wading in shallow water or perching in low trees and bushes along the shore. They are also excellent fliers and soar well.

They are plant eaters. Screamers graze on grasses and on the leaves, stems and seeds of aquatic plants, much like geese do, and sometimes dig for food. A small row of ridges inside the bill likely helps strip water plants. They are generalists that eat whatever plant matter is most common and easy to reach, including crops and introduced plants such as white clover. Insects and small vertebrates are eaten only rarely. By moving seeds around they may help disperse some plants.

Social habits shift with the seasons. Outside the breeding season, flocks of up to about 100 birds gather to feed around shallow pools. When breeding starts, pairs break away and become solitary and fiercely territorial around their nests.

The call explains the name. Both sexes give an extremely loud, two-toned trumpet, written as "ca-WOOW" or "oh-WOOOW," that can be heard up to 3 km (2 mi) away. One field description calls it "a low, throaty, almost barking" sound. The female's voice is a little weaker and higher than the male's. Screamers call in flight and while perched, mainly as an alarm or between mates, and their vocabulary is small beyond that.

Predators rarely take adult screamers. Their size, loud alarm calls and wing spurs make them a poor target, and a threatened bird will strike with its powerful wings and gouge an attacker with the spurs.

Southern screamers form long-term pairs, some lasting for life. Couples preen each other and call in duets, even from far apart, all year round. Together they build a large nest of sticks and reeds on the ground near shallow water, often returning to about the same place for several years. Females lay two to seven white eggs, typically three to five. Both parents incubate them for 43–46 days and both care for the chicks, which fledge at eight to ten weeks and become independent at about 12 to 13 weeks.

Range and habitat

The southern screamer is a permanent resident of southeastern South America. Its range runs from the eastern half of Bolivia south into Argentina as far as Buenos Aires Province, and east through Paraguay into southwestern Brazil and Uruguay. It has also turned up as a vagrant in southeastern Peru.

It is a wetland specialist. Screamers live in tropical and subtropical lakes, open marshes, swamps and flooded meadows with scattered trees, anywhere there is plenty of vegetation. They are especially common in the Pantanal floodplains of Brazil. The species is generally considered non-migratory, though changing numbers in coastal and inland parts of Brazil's Rio Grande do Sul hint at local seasonal movements. They also gather in crop fields.

Conservation status

The IUCN rates the southern screamer as Least Concern, most recently in a 2024 assessment by BirdLife International. The species has a very large range. Population estimates vary widely, from 100,000 to 1 million birds, but the population is believed to be stable.

No immediate threats have been identified. Deforestation, the draining of wetlands for farming and persecution by farmers who see the birds as crop pests are potential problems, but the species seems able to compensate fairly well. Screamers are sensitive to human activity, which makes them a possible indicator of how heavy human use affects wetlands.

People and screamers also cooperate. Because their alarm call is so loud and far-carrying, local people sometimes keep tame screamers as guard birds to protect livestock.