Black-necked Swan Identification Guide

Key Field Marks

• Smallest of the world's swan species, with an all-white body and a strikingly contrasting black head and neck — a pattern unique among swans.
• Bill is gray-blue with a prominent bright red knob (caruncle) at the base in adults, larger and brighter in breeding males.
• Neck is proportionally shorter and held less rigidly upright than in the larger white swans of the Northern Hemisphere.
• Juveniles are duller, with grayish rather than crisp black-and-white plumage, gradually acquiring adult coloration.

Behavior

• Forms strong pair bonds and is often seen in pairs or family groups; also gathers in larger flocks on productive wetlands outside the breeding season.
• Feeds mainly by upending or dabbling in shallow water for aquatic vegetation, and also grazes on land at times.
• Nests on platforms of vegetation near or over water, often on small islands or dense marsh vegetation for protection from predators.

Separating from Similar Species

• Unmistakable within its native range — no other swan species is found in southern South America, and the black head/neck versus white body pattern is unique among all swans worldwide.
• Coscoroba Swan: sometimes found alongside Black-necked Swan in the same wetlands but is entirely white with a red bill and legs and no black on the head or neck at all.

Habitat & Range

• Native to southern South America, including southern Chile, Argentina, southern Brazil, and the Falkland Islands.
• Inhabits freshwater and brackish lakes, lagoons, marshes, and sheltered estuaries with abundant aquatic vegetation.
• Partially migratory in the far south of its range, with some populations shifting north to milder wetlands in winter.

Voice

• Gives soft, melodious whistling calls, notably quieter and less trumpeting than the loud bugling calls of Northern Hemisphere swans such as Trumpeter or Whooper Swan.