Adults average 102 to 124 cm (40 to 49 in) and weigh 3.5-6.7 kg (7.7-14.8 lbs). The wingspan ranges from 135 to 177 cm (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. The cygnet has a light grey plumage with black bill and feet. The Black-necked Swan was formerly placed inmonotypic genus, Sthenelides.
The smallest member in its genus, it is found in freshwater marshes, lagoon and lake shores in southern southamerica. The Black-necked Swan breeds in ChileaSautherm, Patagonia, Tierra del Fuego and on theFalkland island. In the austral winder, this species migrates northwards to Paraguay and southern Brazil.The wetlands created by the reat Chilean Earthquake like Carlos Anwandter Nature Sanctuary inCruces river have become important population centers for the Black-necked Swan.
In 2004 and 2005 thousands of Black-necked Swans in the Carlos Anwandter Nature Sanctuary in Chile died or migrated away following major contamination by Valdivi pulp mill located on the Cruces river which feeds the wetlands. By August 2005 the birds in the Sanctuary had been "wiped out"; only four birds could be observed from a population formerly estimated at 5,000 birds. Autopsies on dead swans attributed the deaths to high levels of iron and other metals polluting the water.
The Black-necked Swan, like its nearest relatives the Black and mute swam is relatively silent. Also, unlike most wildfowl, both parents regularly carry the Cygnes 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.
Widespread and common throughout its habitat, the Black-necked Swan is evaluated as Least Concern on the IUCN Red List of Threatened Species. It is listed on Appendix II of CITES.
The information here was taken from the website called WIKIPEDIA
the experience I had at the zoo was very good because I met did not know animals or animals that knew also known but not seen and the animal that I liked was a bird that if one said to dance the dance.