The bar-headed goose is typically a migratory species, flying southwards in the winter to northern India and adjacent countries (3). Although the migration routes taken by this species are relatively poorly known (3), the bar-headed goose has been reported to migrate over the Himalayas at impressive altitudes of between 9,000 and 10,000 metres (3) (4). Unique physiological adaptations enable this species to carry out such a feat (4).
The bar-headed goose is a primarily herbivorous species (4) (3), foraging mostly by grazing on land, but also feeding on the water (3). This species eats a variety of grasses, roots, leaves, stems, seeds and berries during the breeding season, as well as small insects and crustaceans. In winter the bar-headed goose also eats grain, tubers and other vegetables, with coastal populations also being known to feed on seaweed, and where available this species will also take crops including beans and peas. Interestingly, the bar-headed goose demonstrates a high tolerance for otherwise poisonous plants, including Convallaria majalis (3).
The breeding season of the bar-headed goose generally starts in late May or June (2) (3). This species tends to form long-term monogamous pairs (3), with colonies often containing more than 1,000 pairs (3) (4), but it is also known to form harem groups consisting of one male and up to five females (3). In its native range, the bar-headed goose builds its nest at high altitude (4). This species is usually a ground nester, building a shallow nest of vegetation lined with down (3) among marshes, along rivers or next to lakes (3) (4), although it is also known to nest in trees (3). The bar-headed goose generally returns to the same nesting site year on year (3).
The female bar-headed goose usually lays a clutch of between four and six eggs (2) (3), although clutches can range in size from three to eight eggs (3). Incubation lasts between 27 and 30 days (3) (4), and is carried out by the female alone (3). Bar-headed goose goslings are able to leave the nest site two days after hatching, and are capable of feeding themselves just one or two days later (3). The young birds take their first flight at about 53 days of age, and fledge between 65 and 80 days of age. During the autumn migration and the ensuing winter period, family parties tend to stay together. The bar-headed goose is thought to reach sexual maturity at about two or three years old (3).