Brent Geese

Brent geese (Branta bernicla) are members of the genus Branta, the so-called black geese, which includes the Canada goose of North America and the barnacle goose of Greenland, Svalbard, and Arctic Russia. There are seven recognized races of brent geese, all of which winter along coasts where they feed mainly upon sea grasses, especially subtidal and intertidal Zostera.

All brent geese are distinctive from other geese in having a completely sooty black head, neck, and upper breast; this is the smallest of all geese, little bigger than a Mallard. The sexes are alike, but the pale edgings to feathers on the folded wings distinguish the birds of the year from older geese. First winter birds also lack the distinctive white "necklace" on the throat that characterize the adults. Underparts are dark slate-gray in the nominate race bernicla, almost black in nigricans, and variably pale gray to almost white in hrota.

Seven distinct populations are recognized as follows:

1. The dark-bellied brent goose B. b. bernicla breeds mainly along coasts of the Taymyr Peninsula from 73 to 79° N and from 75 to 122° E, with recent expansion of the breeding range westward to the Yamal and Kanin peninsulas. This population winters along coasts of western Europe, from the Atlantic coast of France, south and eastern coasts of England, southwest Netherlands and in the Wadden Sea as far north as Denmark. Satellite telemetry and recent field observations have confirmed the importance of the White Sea in spring and autumn as staging areas for their long migrations to and from breeding areas. Following apparent declines in the Zostera food stocks, this population fell from several hundred thousand to 20,000 in the 1930s, with 16,500 counted in the earliest complete counts of the mid-1950s. Following protection from hunting in Denmark in 1972, numbers rose rapidly tomore than 300,000 at present.

2. The black brant B. b. nigricans breeds on Banks Island, through the Queen Maud Gulf Sanctuary, in Alaska and the far eastern Russian Arctic as far west as eastern Taymyr. It is thought that most, if not all, congregate in Izembek Lagoon in October before migrating on to winter along the Pacific coast, primarily in Baja California, Mexico. This population numbers some 120-140,000 birds.

3. The gray-bellied brant B. b. hrota breeds exclusively in the Canadian High Arctic, probably confined to Melville Island, Prince Patrick Island, and small islands nearby. This group is thought to winter exclusively in Padilla Bay, Washington, but small numbers are seen among Pacific black brant down into Mexico. This population is poorly known and only recently recognized as being morphologically separate from other forms. Its numbers are considered to be critically small, probably numbering 8-10,000 birds in all.

4. The Atlantic brant B. b. hrota nests on Baffin Island and Somerset Island in the Canadian Arctic winter along the Atlantic coast of North America from Massachusetts to North Carolina. This population numbers some 106,000 individuals and has shown reasonably stable trends for the last 30 years.

5. The black-bellied brent geese B. b. nigricans that pass through Hokkaido in Japan in autumn number at least 5000 individuals. Although 2500 remain to winter in Japan, it is not known where the remainder spend the winter. The population uses coasts of Korea and China, but the precise breeding area of this population remains unknown at present.

6. Between 19 and 24,000 light-bellied brent geese B. b. hrota winter in Ireland, passing through Iceland on migration to and from their High Arctic Canadian breeding areas. Their breeding areas lie in the eastern Queen Elizabeth Islands from eastern Melville Island (108° E) to northern Ellesmere Island, although the precise breeding distribution remains unknown.

7. Another group of light-bellied brent geese breed on Svalbard and in northeast Greenland and winter in Denmark and Lindisfarne on the northeast coast of England. This population numbers some 6000 individuals and has shown a very slow increase in numbers in recent years.

Brent geese nest on the High Arctic open tundra, but are extremely sensitive to predation, their small size making them no match for an Arctic fox (Alopex lagopus). Breeding success is typically highly erratic, with the number of young in autumn population, varying greatly between years. Almost complete non-breeding seasons are a regular feature of the dark-bellied brent population, alternating with years with up to 50% young in the autumn flocks. This pattern is influenced by the three-year lemming Lemmus sibiricus cycle on the Taymyr Peninsula, although the spring condition achieved in the Wadden Sea prior to departure in spring also has an impact on subsequent breeding success. In contrast, delayed snowmelt in the Queen Elizabeth Islands makes it easier for predators (such as Arctic fox, polar bear Ursus maritimus, gulls Larus spp., skuas Stercorarius spp., or ravens Corvus corax) to find nests, but there seems to be no cyclicity in their reproductive success. The Svalbard population shows similar swings in breeding output, dependent in part on sea ice conditions that affect the likelihood of polar bears being present on the nesting islands in spring. Throughout their winter range, brent geese are marine in habit, with all the above populations exploiting eelgrasses Zostera for most of their annual cycle outside of the breeding period. Many switch to saltmarshes in spring, when the eel-grass stock is depleted and new grass growth is protein rich to support accumulation of stores in preparation for spring migration. Brent geese are and continue to be important food for native peoples: remains are known from middens on Ellesmere Island from 1900 BC to AD 1000 and the species has long been important for the Yup'ik people of the Yukon-Kuskokwim Delta.

Tony Fox

See also Barnacle Goose

Further Reading

Bellrose, F.C., "Ducks, Geese and Swans of North America,"

Harrisburg: Stackpole, 1976 Boyd, H., L.S. Maltby-Prevett & A. Reed, "Differences in the plumage patterns of Brant breeding in high arctic Canada." Canadian Wildlife Service Progress Notes, 174 (1988): 1-9 Clausen, P. & J.-O. Bustnes, "Flyways of the North Atlantic Light-bellied Brent Geese Branta bernicla hrota reassessed by satellite telemetry." Norsk Polarinstitutt Skrifter, 200 (1998): 269-286 Cramp, S. & K.E.L. Simmons, The Birds of the Western Palearctic, Volume 1, Oxford: Oxford University Press, 1977

Del Hoyo, J., A. Elliot. & J. Sartagal, Handbook of the Birds of the World, Volume 1, Ostrich to Ducks, Madrid: Lynx, 1992 Ebbinge, B.S. & B. Spaans, "The importance of body reserves accumulated in spring staging areas in the temperate zone for breeding in dark-bellied brent geese Branta b. bernicla in the high Arctic." Journal of Avian Biology, 26 (1995): 105-113

Madge, S. & H. Burn, Wildfowl: An Identification Guide to the Ducks, Geese and Swans of the World, London: Helm, 1987 Madsen, J., T. Bregnballe, J. Frikke & J.B. Kristensen, "Correlates of predator abundance with snow and ice conditions and their role in determining timing of nesting and breeding success in Svalbard light-bellied brent geese Branta bernicla hrota." Norsk Polarinstitutt Skrifter, 200 (1998): 213-226 Madsen, J., G. Cracknell & A.D. Fox, Goose Populations of the Western Palearctic: A Review of Status and Distribution, Wageningen & R0nde: Wetlands International and NERI, 1999

Reed, A., D.H. Ward, D.V. Derksen & J.S. Sedinger, "Brant."

Birds of North America No. 337, Philadelphia: BNA, 1998 Spaans, B., M. Stock, A.K.M. St Joseph, H.H. Bergmann & B.S. Ebbinge, "Breeding biology of dark-bellied brent geese Branta bernicla bernicla in Taimyr in 1990 in the absence of arctic foxes and under favourable weather conditions." Polar Research, 12(2) (1995): 117-130

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