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 A Swan Goose in China
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| Anser cygnoides (Linnaeus, 1758) |
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Cycnopsis cygnoides |
The Swan Goose (Anser cygnoides) is a large goose with a natural breeding range in Mongolia, northernmost China, and southeastern Russia. It is migratory and winters mainly in central and eastern China. The species has been domesticated, and introduced and feral populations occur elsewhere.1
It is large for its genus, 81–94 cm long (the longest Anser goose) and weighing 2.8–3.5 kg (the second-heaviest Anser, after the Greylag Goose). It has a long neck, long, heavy black bill, brown cap and pale underparts apart from some belly streaking; the upperparts are brown and the legs are orange. The sexes are similar, although the male is larger, and juveniles are duller. The voice is a loud honking. It grazes on sedges, and rarely swims. It forms small flocks outside the breeding season.1
It is a rare goose of steppes and mountain valleys, which breeds near marshes and other wetlands, laying 5–8 eggs in a ground nest. In the winter, it grazes on steppes and stubble, sometimes far from water.1
The Swan Goose was listed as endangered in the wild, the population declining due to habitat loss and excessive hunting2, but new research has shown it to be not as rare as it was believed. Consequently, it was downlisted to vulnerable status in 20083.
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Domestication
Though the majority of domestic geese are descended from the Greylag Goose, two breeds are direct descendants of the Swan Goose: the Chinese Goose and the African Goose. These breeds have been domesticated since at least the mid-eighteenth century, and vary considerably from their wild parent in appearance, temperament, and ability to produce meat and eggs.4
Charles Darwin studied goose breeds as part of his work on the theory of evolution. He noted that the external differences between Chinese geese and breeds descended from the Greylag Goose belied a rather close relationship:
"The hybrids from the common and Chinese geese (A. cygnoides), species which are so different that they are generally ranked in distinct genera5, have often bred in this country with either pure parent, and in one single instance they have bred inter se."6
Footnotes
- ^ a b c Madge & Burn (1987), Carboneras (1992)
- ^ Carboneras (1992)
- ^ BLI (2008)
- ^ Ekarius, Carol (2007). Storey's Illustrated Guide to Poultry Breeds. 210 MAS MoCA Way, North Adams MA 01247: Storey Publishing. ISBN 978-1-58017-667-5.
- ^ The Swan Goose had been separated in the monotypic genus Cygnopsis (alternatively spelled Cycnopsis) some 20 years before Darwin wrote this. Cygnopsis cygnoides essentially means "Swan lookalike", Cygnopsis signifying "looking like a swan" and cygnoides "similar to a swan".
- ^ Darwin (1859): p.253
References
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Wikimedia Commons has media related to: Anser cygnoides |
- BirdLife International (BLI) (2006). Anser cygnoides. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 23 May 2008.
- BirdLife International (BLI) (2008): [2008 IUCN Redlist status changes. Retrieved 2008-MAY-23.
- Buckland, Roger & Guy, Gérard (eds.) (2002): Goose Production. FAO Animal Production and Health Papers 154. ISBN 92-5-104862-2 PDF fulltext
- Carboneras, Carles (1992): 18. Swan Goose. In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.): Handbook of Birds of the World, Volume 1 (Ostrich to Ducks): 581, Plate 41. Lynx Edicions, Barcelona. ISBN 84-87334-10-5
- Darwin, Charles (1859): On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. John Murray, London. HTML fulltext
- Madge, Steve & Burn, Hilary (1987): Wildfowl : an identification guide to the ducks, geese and swans of the world. Christopher Helm, London. ISBN 0-7470-2201-1
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- This page was last modified on 5 September 2008, at 10:51.
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