The coscoroba swan (Coscoroba coscoroba) is a species of waterfowl in the subfamily Anserinae of the family Anatidae. It is found in Argentina, Bolivia, Brazil, Chile, Paraguay, Uruguay, and the Falkland Islands.
Taxonomy and systematics
The coscoroba swan's placement within the family Anatidae is not fully agreed upon, with a 2014 genetic study positing a phylogenetic relationship between this species and the Cape Barren goose (Cereopsis novaehollandiae). BirdLife International's Handbook of the Birds of the World has adopted this approach and puts the coscoroba swan and Cape Barren goose together in the tribe Cereopsini, which it places as basal to Cygnus and all other geese.
The coscoroba swan is the only member of the genus Coscoroba and has no subspecies. Physically, coscoroba swans have been compared to the American Pekin duck, albeit larger and with darker, redder bills and feet (Pekin ducks have bright orange bills and feet). The genders have the same plumage. Upon hatching, the chicks have blue-grey bills and feet and black striping running down the length of their bodies (to aid in camouflage from predators), with this eventually fading by about eight months of age. The adults are completely white, except for black tips to the outer six primary feathers, though this black is often barely visible on the closed wing unless the bird is in flight.
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Coscoroba coscoroba -Argentina -flying-8.jpg
Coscoroba swans (Coscoroba coscoroba) in flight Laguna Nimez.jpg
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Distribution and habitat
The coscoroba swan is a year-round resident of central Argentina and along the Uruguay-southern Brazil coast. It also breeds, but does not winter from southern Chile and Argentina south to Tierra del Fuego and occasionally to the Falkland Islands. In winter, its range extends north to central Chile, northern Argentina, Paraguay, Uruguay, and southern Brazil. It has been recorded as a vagrant in Bolivia and at several locations in Brazil north of its usual limit. The coscoroba swan inhabits well-vegetated lagoons, freshwater swamps, and sometimes human-made reservoirs. It is mainly a bird of the lowlands, though there are scattered records as high as and at least one at .