The Black-necked Swan is the largest waterfowl native to South America.
Adults average 40 to 49 in and weigh 7.7-14.8 lbs. The wingspan ranges from 53 to 70 in. The body plumage is white with a black neck, head and greyish bill. It has a red knob near the base of the bill and white stripe behind eye. The sexes are similar, with the female slightly smaller.
It is found in freshwater marshes, lagoon and lake shores in southern South America. The Black-necked Swan breeds in Chilean Southern Zone, Patagonia, Tierra del Fuego and on the Falkland Islands. In the austral winter, this species migrates northwards to Paraguay and southern Brazil. The wetlands created by the Great Chilean Earthquake like Carlos Anwandter Nature Sanctuary in Cruces River have become important population centers for the Black-necked Swan.
The Black-necked Swan is relatively silent.Unlike most wildfowl, both parents regularly carry the cygnets on their backs. The female lays four to six eggs in a nest of vegetation mound. The diet consists mainly of vegetation, insects and fish spawn.