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Cygnus columbianus
Diet
Aquatic vegetation in summer; leftover crops such as potatoes at other times
Habitat
Arctic breeding grounds; nest beside water
Clutch size
2–7 eggs
Incubation period
About 30 days
Size
115–150cm
Wingspan
168–211cm
Weight
3.4–9.6kg
The tundra swan is the smallest of the Holarctic swans, 115 to 150cm long with a wingspan of 168 to 211cm and a weight of 3.4 to 9.6kg. Adult plumage is entirely white, with black feet and a black bill carrying varying amounts of yellow. It makes a high-pitched honk like a black goose, and birds in iron-rich water may acquire a golden or rusty tint on the head and neck (Wikipedia, general species account).
It breeds in the Arctic and overwinters in North America, Europe and Asia. In May it builds a nest beside water from plant material and lays two to seven eggs, incubated for about 30 days. The young fledge after 60 to 75 days. Vagrants may appear south of the main wintering range in cold years, and Nepal is named among the places where such vagrants have been recorded.