The Coscoroba Swan breeds in South America from southern Chile and central Argentina south to Tierra del Fuego and the Falkland Islands. In winter it flies north to central Chile, northern Argentina, Uruguay and the south east tip of Brazil. It is the smallest species of swan, and a taxonomic conundrum: it is swan-like overall, but its honking voice and goose-like head make it somewhat indistinguishable. Its bill looks like a duck and it is the only swan with offspring that look like tree ducks. Some scientists, who believe it to be a member of the swans, think there is a link either between swans and true geese, or between swans and whistling ducks. The name was given to it by South American Indians as its call sounds like cos-cor-ro-oa.
Coscoroba swans feed mainly on grass and water plants, but also eat mussels, oysters and small fish. Coscorobas, in addition to most ducks and flamingos, utilize a method of feeding which involves combining water and edible material in their bill and then squirting the water out through comb-like lamellae on the sides of their mouth. Their buoyancy on water is due to air held in plumage. Body plumage is continually covered by oil from the preen gland. They are very careful not to get water under their plumage. These birds have flapping flight and are unable to glide or soar extensively.
The above picture was taken at the Artis Zoo of Amsterdam, in July 2005.
Life on Earth