Black-necked Swan

Overview

The Black-necked Swan is the only swan native to South America, found from central Chile and Argentina south to Tierra del Fuego and the Falkland Islands. Its bold two-toned plumage makes it one of the most visually distinctive waterfowl species in the region.

Unlike many swans that are entirely white, this species carries a striking black neck and head, immediately setting it apart from all other swan species worldwide.

Feather Identification

• Body feathers: pure white across the entire body, wings, and underparts
• Neck and head feathers: solid glossy black, sharply demarcated from the white body at the base of the neck
• Facial marking: a thin white line runs behind the eye, breaking up the black head slightly
• Bare parts: a bright red knob (caruncle) sits at the base of the bill, contrasting with the black facial feathering
• Flight feathers: white primaries and secondaries, visible as a solid white wing in flight
• The combination of an all-white body with a solid black neck is unique among swans and makes this species instantly identifiable even from a distance

Plumage Details

Adults of both sexes look alike, with males slightly larger than females. The stark white body plumage remains constant year-round with no seasonal color change, while the black neck and head feathers stay glossy black in all seasons.

Cygnets (juveniles) are grayish overall with a paler, mottled neck, gradually acquiring the adult black-and-white pattern and red facial knob as they mature over the first year. Adults undergo a complete molt after breeding, during which they become flightless for several weeks like other swans.

Habitat & Range

Black-necked Swans inhabit freshwater lakes, marshes, lagoons, and sheltered coastal bays across temperate and subantarctic South America, including central and southern Chile, Argentina, and the Falkland Islands. Southern populations are partially migratory, moving northward to escape the harshest winter conditions, while others remain resident where open water persists year-round.

Behavior & Field Notes

These swans are social outside the breeding season, often gathering in flocks on open water, but become territorial and pair off during nesting. Diet consists mainly of aquatic vegetation, algae, and small invertebrates gathered by dabbling or upending in shallow water.

Nests are large mounds of vegetation built near the water's edge or on floating platforms in marshes. The voice includes soft whistling and low trumpeting notes, quieter than those of some larger swan species. In the field, the sharp white-body/black-neck contrast is visible from a great distance, making this one of the easiest waterfowl species to identify on sight.