The coscoroba swan (Coscoroba coscoroba) gets its name because of its loud, ringing 'cos-cor-ooo' when vocalizing. It is the smallest of the birds called "swans", but still a large species of waterfowl. It is swanlike 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. Coscorobas display typical swanlike threats that involve lifting their folded wings to make them appear larger. Aggressive wing flapping is also a typical threat. But the Coscoroba Swan lacks the black face mask of the other swans (between the eyes and beak, known as "lores") and compared to other swans, the Coscoroba Swan has a much smaller body, shorter neck, and longer legs. 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. It occurs naturally in South America, where it inhabits well-vegetated swamps and lagoons.