The barnacle goose, or Branta leucopsis, is an arctic species of goose that has its breeding grounds in Greenland, Norway, and Northern Russia. This species typically migrates to England, Ireland, and Scotland in the winter, or to Germany and the Netherlands in the case of Russian birds. Barnacle geese typically have a black neck and crown, a white face, gray flanks, a gray breast, and a black back. Both males and females of this species have the same markings, though males may be larger than females.
These geese take their name from the medieval belief that they developed from goose barnacles. Historians believe that this theory developed because medieval scientists did not understand bird migration patterns, and therefore sought an explanation for the sudden appearance of non-native bird species in some regions in the winter. Because barnacle geese were believed to develop from barnacles, medieval Europeans widely considered them a form of fish. The barnacle goose is therefore believed to have been a food staple during Lent, when meat could not be eaten.
The barnacle goose has a black crown and neck, with a white face resembling a mask. They also have black plumage on their backs, and black feet. The sides, breast, and flanks of the barnacle goose are gray. The barnacle goose also has a distinctive white rump.
Unlike some other bird species, there is generally no discernible difference in markings between the male and the female of the species. Males are typically more robust than females, weighing about 4.03 pounds (1.8 k), while the female usually weighs about 3.57 pounds (1.6 k). The male barnacle goose may grow to a length of 27 inches (68.5 cm), while the female barnacle goose typically reaches a maximum length of 23.5 inches (59.7 cm).
Barnacle geese are an arctic bird. Their breeding grounds are mostly located on the northern coast of Greenland. Breeding grounds have also been found in Svalbard, Norway, and the Russian islands of Vaygach Island and Novaya Zemlya. Barnacle geese typically form small nesting colonies on cliffs or among island crags. They often nest in proximity to Gyr falcons to protect themselves from arctic foxes. One female goose may lay four to six eggs per breeding season.
These birds migrate to England, Scotland, Ireland, Germany and the Netherlands, where they winter in the mud flats, estuaries, coastal marshes, and grasslands of these regions. They feed on seeds, roots, leaves, and stems.
While barnacle geese have been sighted in northeastern North America, they are not considered a North American bird. No barnacle geese breeding grounds have yet been found in North America, and the region is not believed to form a part of their migratory path. Some believe that barnacle geese are only sighted in North America when they escape from domestic captivity.