Barnacle geese are medium-sized birds that breed mainly on the Arctic islands of the North Atlantic. They have a white face and black head, neck, and upper breast; their belly is white. The wings and their back are silver-gray with black-and-white bars that look like they are shining when the light reflects on it. During the flight, these birds show a V-shaped white rump patch and the silver-gray underwing linings.
Barnacle geese occur in three main populations, with separate breeding and wintering ranges, from west to east which include eastern Greenland, Svalbard and Novaya Zemlya (northern Russia and the extreme northeast of Europe). A new fourth population, derived from the Novaya Zemlya population, has become established since 1975 breeds on the islands and coasts of the Baltic Sea (Estonia, Finland, Denmark, and Sweden). Occasionally, wild birds will appear in the Northeastern United States or Canada. Breeding habitats include coastal tundra with cliffs, rocky outcrops, and steep slopes, often near lakes, rivers, and marshes. On the wintering grounds, Barnacle geese prefer grassy fields near the coastal regions, mudflats, and salt marshes.
Barnacle geese are gregarious birds; they nest, feed and migrate in large flocks. They are active during the day spending most of the time foraging above-ground. Barnacle geese moult after nesting; during this time they can't fly and stay in protected areas such lakes or at sea in order to avoid predators. After the moulting period, birds usually congregate at the gathering sites, where they feed before the migration to their wintering grounds.
Barnacle geese are monogamous and form long-lasting pair bonds. They breed in late May-June usually in colonies that may include up to 50 pairs. Females construct the nests locating them on cliff edges in order to avoid predators. The nest is made of dead foliage and mud and lined with down. The female lays 3 to 5 white eggs, and incubates them during 24-26 days; during this time the male feed and protects her. At hatching, goslings are precocial (fully-developed); they are able to leave the nest soon after birth and follow their parents to nearby marshes to feed themselves. The young fledge at 40 to 45 days old and become reproductively mature when they are 2-3 years old.
Barnacle geese are persecuted by farmers because during the winter they often visit fields and farmlands to feed on grass. In Svalbard, these birds also suffer from predation by Arctic foxes which hunt adult birds, eggs and newly hatched goslings.
According to the IUCN Red List, the total population size of the Barnacle goose is around 880,000 individuals. The European population consists of 196,000-247,000 pairs, which equates to 392,000-494,000 mature individuals. According to the Wikipedia resource, the species population numbers have been estimated in such areas: Greenland - about 40,000 individuals; Svalbard - about 24,000 individuals; Novaya Zemlya (Russia) - about 130,000 individuals; on the islands and coasts of the Baltic Sea (Estonia, Finland, Denmark, and Sweden) - about 8,000 individuals. Overall, currently, Barnacle geese are classified as Least Concern (LC) on the IUCN Red List and their numbers today are increasing.
Barnacle geese are important seed dispersers in their ecosystem as they feed on a wide variety of herbs and grasses. These birds are also a food source for local predators such as falcons, polar bears, and Arctic foxes.