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Brant (goose)

(Redirected from Brent geese)
"Black Brant" redirects here. For the rocket, see Black Brant (rocket).

The brant or brent goose (Branta bernicla) is a small goose of the genus Branta. There are three subspecies, all of which winter along temperate-zone sea-coasts and breed on the high-Arctic tundra.

Brant
Calls recorded in West Sussex, England
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Branta
Species:
B. bernicla
Binomial name
Branta bernicla
Global map of range[2]
  Winter non-breeding range
  Summer breeding range
Synonyms

Anas bernicla Linnaeus, 1758

The Brent oilfield was named after the species.[3]

Taxonomy

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The brant was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Anas bernicla.[4][5] Linnaeus specified the type locality as Europe but in 1761 restricted it to Sweden.[5][6] The brant is now one of six species placed in the genus Branta that was introduced in 1769 by the Austrian naturalist Giovanni Antonio Scopoli.[7] The genus name Branta is a Latinised form of Old Norse brandgás, "burnt (black) goose". The specific epithet bernicla is Medieval Latin for barnacle.[8]

The brant and the similar barnacle goose were previously considered to be the same species and believed to be the same creature as the barnacle.[8] That myth can be dated back to at least the 12th century. Gerald of Wales claimed to have seen these birds hanging down from pieces of timber, William Turner accepted the theory, and John Gerard claimed to have seen the birds emerging from their shells. This myth arose because in the 1100s the migration of birds was unknown, but it was known that none of these birds was ever seen nesting, nor were eggs found, nor were goslings seen.[9] The legend persisted until the end of the 18th century. In County Kerry, until relatively recently, Catholics could eat this bird on a Friday because it counted as fish.[10]

Three subspecies are recognised:[7]

  • B. b. nigricans (Lawrence, 1846) – breeds northeast Siberia, Alaska and northwest Canada
  • B. b. bernicla (Linnaeus, 1758) – breeds northwest, central north Russia
  • B. b. hrota (Müller, OF, 1776) – breeds northeast Canada, Greenland and Svalbard

Description

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Wintering at the Wadden Sea, Germany
 
Feeding in Long Island Sound, Connecticut
 
Eggs, Collection Museum Wiesbaden

The brant is a small goose with a short, stubby bill. It measures 55–66 cm (22–26 in) long, 106–121 cm (42–48 in) across the wings and weighs 0.88–2.2 kg (1.9–4.9 lb).[11][12][13][14] The under-tail is pure white, and the tail black and very short (the shortest of any goose).

The body of the dark-bellied nominate subspecies B. b. bernicla is fairly uniformly dark grey-brown all over, the flanks and belly not significantly paler than the back. The head and neck are black, with a small white patch on either side of the neck. With a population of about 250000, it breeds on the Arctic coasts of central and western Siberia and winters in coastal areas of western Europe, with over half the population in southern England, the rest between northern Germany and south-western France.

The pale-bellied form B. b. hrota appears blackish-brown and light grey in colour. The body is different shades of grey-brown all over, the flanks and belly are significantly paler than the back and present a marked contrast. The head and neck are black, with a small white patch on either side of the neck. The total population is about 250,000, with the main population breeding in northeastern Canada and wintering along the Atlantic coast of the U.S. from Maine to Georgia,[11] and two smaller populations, one breeding in Franz Josef Land, Svalbard, and northeastern Greenland and wintering in Denmark, northeast England, and Scotland, and the other breeding in the far-northeastern Canadian islands and wintering in Ireland, southwest England, and in a small but significant area, le havre de Regnéville, centered on the Sienne Estuary in Manche (Northern France).[15] In Ireland it is recorded in winter from a number of areas including Lough Foyle, Strangford Lough, Tralee Bay and Castlemaine Harbour.[16][17][18]

The black form B. b. nigricans appears blackish-brown and white in colour. This form is a very contrastingly black and white bird, with a uniformly dark sooty-brown back, similarly coloured underparts (with the dark colour extending furthest back of the three forms) and a prominent white flank patch; it also has larger white neck patches, forming a near-complete collar. The population of about 125,000 breeds in northwestern Canada, Alaska and eastern Siberia, and winters mostly on the west coast of North America from southern Alaska to California, but also some in east Asia, mainly Japan, also Korea and China. The population has been as high as 200,000 in 1981, and as low as 100,000 in 1987.[19]

The Asian populations of the black brant populations had previously been regarded as a separate subspecies B. b. orientalis based on purported paler upperparts coloration; however, it is generally now believed that this is not correct, and they are assigned to B. b. nigricans.

A fourth form (sometimes known as the 'gray-bellied brant) has been proposed, although no formal subspecies description has been made as yet, for a population of birds breeding in central Arctic Canada (mainly Melville Island), and wintering on Puget Sound on the American west coast around the U.S./Canada border. These birds are intermediate in appearance between black brant and pale-bellied brant, having brown upperparts and grey underparts which give less of a contrast with the white flank patch. It has also been proposed that, rather than being a separate subspecies, it is actually a result of interbreeding between these two forms, given that this population exhibits mixed characters.[20]

Individual birds when wintering generally remain in loose family-groups, together with others of the same sub-species, but there is overlap in some areas (for example Western Europe, see above); and this is also true in the breeding colonies. Outside the breeding season, individuals with characteristics of any subspecies may occasionally turn up with regular migrants, and there has been debate as to whether this is related to migration routing accidents, or to breeding range overlap, or even interbreeding.

Habitat

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In a defensive position
 

The brant goose was strictly coastal bird in winter, rarely leaving tidal estuaries, where it feeds on eelgrass (Zostera marina)[21] and the seaweed, sea lettuce (Ulva).[11][22] On the east coast of North America, the inclusion of sea lettuce is a recent change to their diet, brought about by a blight on eelgrass in 1931. This resulted in the near-extirpation of the brant. The few that survived changed their diet to include sea lettuce until the eelgrass eventually began to return. Brants have maintained this diet ever since as a survival strategy.[23] A similar collapse in eelgrass in Ireland in the 1930s also negatively impacted the population.[24] In recent decades, it has started using agricultural land a short distance inland, feeding extensively on grass and winter-sown cereals. It has been suggested that they learnt this behaviour by following other species of geese. Food resource pressure may also be important in forcing this change, as the world population increased over 10-fold to 400,000-500,000 by the mid-1980s, possibly reaching the carrying capacity of the estuaries. In the breeding season, it uses low-lying wet coastal tundra for both breeding and feeding. The nest is bowl-shaped, lined with grass and down, in an elevated location, often near a small pond.

Conservation status

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The brant is listed as a species of "Least Concern" by the International Union for Conservation of Nature (IUCN).[1] It is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.[25]

References

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  1. ^ a b BirdLife International (2016). "Branta bernicla". IUCN Red List of Threatened Species. 2016: e.T22679946A85966135. doi:10.2305/IUCN.UK.2016-3.RLTS.T22679946A85966135.en. Retrieved 12 November 2021.
  2. ^ Lewis, Tyler L.; Ward, David H.; Sedinger, James S.; Reed, Austin; Derksen, Dirk V.; Carboneras, Carles; Christie, David; Kirwan, Guy M. (4 March 2020). Billerman, Shawn M (ed.). "Brant (Branta bernicla)". Birds of the World. doi:10.2173/bow.brant.01.
  3. ^ "UK Brent Oil". One Financial Markets. Archived from the original on 15 February 2016. Retrieved 25 August 2014.
  4. ^ Linnaeus, Carl (1758). Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1 (10th ed.). Holmiae (Stockholm): Laurentii Salvii. p. 124.
  5. ^ a b Mayr, Ernst; Cottrell, G. William, eds. (1979). Check-List of Birds of the World. Vol. 1 (2nd ed.). Cambridge, Massachusetts: Museum of Comparative Zoology. pp. 444–445.
  6. ^ Linnaeus, Carl (1761). Fauna svecica, sistens animalia sveciae regni mammalia, aves amphibia, pisces, insecta, vermes (in Latin) (2nd ed.). Stockholmiae: Sumtu & Literis Direct. Laurentii Salvii. p. 41.
  7. ^ a b Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (December 2023). "Screamers, ducks, geese & swans". IOC World Bird List Version 14.1. International Ornithologists' Union. Retrieved 15 June 2024.
  8. ^ a b Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 77, 70. ISBN 978-1-4081-2501-4.
  9. ^ Goose Barnacles: Undulating Creatures Retrieved 2011-11-28.
  10. ^ Cocker, Mark; Mabey, Richard (2005). Birds Britannica. London: Chatto & Windus. pp. 78–80. ISBN 0-7011-6907-9.
  11. ^ a b c "Norsk Polarinstitutt". Norsk Polarinstitutt. Retrieved 17 September 2020.
  12. ^ "Brant". All About Birds. Cornell Lab of Ornithology. Retrieved 18 October 2011.
  13. ^ "Brent Goose". Oiseaux-birds.com. Retrieved 18 October 2011.
  14. ^ Dunning, John Barnard (2007). CRC handbook of avian body masses (2nd ed.). Boca Raton: CRC Press. p. 38. ISBN 978-1-4200-6445-2. OCLC 310154556.
  15. ^ Maheo, Roger (1976). "The Brent Geese of France, with special reference to the Golfe du Morbihan". Wildfowl. 27: 45–53.
  16. ^ Ruttledge, R.F. 1966 Ireland's Birds their Distribution and Migration. H.F. & G. Witherby Ltd
  17. ^ "Brent Goose (Light-bellied)". BirdWatch Ireland. Retrieved 17 September 2020.
  18. ^ "Branta bernicla hrota Pale-bellied Brent Goose". habitas.org.uk. Retrieved 17 September 2020.
  19. ^ Slimbridge: Black Brant[permanent dead link]
  20. ^ Lewis, T.L.; Ward, D.H. (2020). Billerman, S.M. (ed.). "Brant (Branta bernicla), version 1.0". Birds of the World. Ithaca, NY, USA: Cornell Lab of Ornithology. doi:10.2173/bow.brant.01. Retrieved 15 June 2024.
  21. ^ Ganter, Barbara (2000). "Seagrass (Zostera spp.) as food for brent geese (Branta bernicla): an overview" (PDF). Helgoland Marine Research. 54 (2–3): 63–70. Bibcode:2000HMR....54...63G. doi:10.1007/s101520050003. S2CID 3832705. Retrieved 8 December 2021. (subspecies, breeding/wintering ranges with flyway maps, diet)
  22. ^ "Brant". Audubon. 13 November 2014. Retrieved 17 September 2020.
  23. ^ Book of North American Birds. 1990.
  24. ^ "Where wild geese fly". The Irish Times. 17 August 2002. Retrieved 17 September 2020.
  25. ^ "AEWA Agreement and Text Annexes" (PDF). Agreement on the Conservation of African-Eurasian Migratory Waterbird. 10 August 2023. Retrieved 15 June 2024.

Further reading

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Wikimedia Commons has media related to Branta bernicla.
 
Wikispecies has information related to Branta bernicla.
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