Although a fairly small swan, the Black-necked Swan is the largest South American waterfowl. They pair for life. Their necks have 24 cervical vertebrate, more than any other warm blooded animal. This long neck is useful in feeding on the bottom of a swamp or water habitat. Their bill is fringed with hairlike lamellae used in filter feeding. I've seen them show a great deal of aggression against other ducks and their young.
