AppearanceThe Swan Goose is large and long-necked for its genus, wild birds being 81–94 cm long and weighing 2.8–3.5 kg or more. The sexes are similar, although the male is larger, with a proportionally longer bill and neck; in fact the largest females are barely as large as the smallest males. Typical measurements of the wing are 45–46 cm in males, 37.5–44 cm in females; the bill is about 8.7–9.8 cm long in males and 7.5–8.5 cm in females. The tarsus of males measures around 8.1 cm. The wingspan of adult geese is 160–185 cm.
The upperparts are greyish-brown, with thin light fringes to the larger feathers and a maroon hindneck and cap . The remiges are blackish, as are the entire underwing and the white-tipped rectrices, while the upper- and undertail coverts are white. A thin white stripe surrounds the bill base. Apart from darker streaks on the belly and flanks, the underside is pale buff, being especially light on the lower head and foreneck which are sharply delimited against the maroon. In flight, the wings appear dark, with no conspicuous pattern. Uniquely among its genus, the long, heavy bill is completely black; the legs and feet, on the other hand, are orange as in most of its relatives. The eyes' irides are maroon. Juveniles are duller than adult birds, and lack the white bill base and dark streaks on the underside.
BehaviorThe voice is a loud drawn-out and ascending honking ''aang''. As a warning call, a similar but more barking honk is given two or three times in short succession.
HabitatIt inhabits steppe to taiga and mountain valleys near freshwater, grazing on plants such as sedges, and rarely swimming. It forms small flocks outside the breeding season. In the winter, it grazes on plains and stubble fields, sometimes far from water.
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