Chen (genus)
From Wikipedia, the free encyclopedia
| iWhite geese | ||||||||||||||
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 Lesser Snow Goose
(Chen caerulescens caerulescens) |
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see text. |
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Philacte Bannister, 1870 |
The white geese are a small group of waterfowl which are united in the genus Chen of the true geese and swan subfamily Anserinae. They breed on subarctic areas of North America and around the Bering Strait, migrating south in winter.
Many authorities place these species in the grey goose genus Anser. Indeed, Chen and Anser are anatomically indistinguishable. However, external morphology, biogeography, and molecular data[citation needed] suggests that these species are indeed an evolutionary lineage distinct from the grey geese, which split off fairly recently and essentially replaces them in North America. The AOU recognizes this genus as distinct.
Like grey but unlike the Branta black geese, their feet and legs are colored in reddish hues. The bill is also reddish in two of the species and in young birds and females of the third (adult males of C. rossii habe a blue-black grainy cere). The wingtips are black, as in all true geese, whereas the head is always white without any markings or pattern in adult birds of this genus, which distinguishes them from all other true geese except feral domesticated geese. The rest of the plumage is either white all over, or colored in various dark bluish-grey hues; the latter birds, uniquely among true geese, do not have white uppertail and undertail coverts, though the tail itself may be white.
White-phase snow geese of both species can be told apart from feral geese best by the more slender, elegant neck, which is thick-set in domestic geese; these also have a generally heavier habitus and often lack black wingtips.
Species
- Snow Goose, Chen caerulescens
- Ross's Goose, Chen rossii
- Emperor Goose, Chen canagica
The supposed fossil dwarf snow goose Chen pressa is now placed in Anser (Brodkorb, 1964).
[edit] References
- Brodkorb, Pierce (1964): Catalogue of Fossil Birds: Part 2 (Anseriformes through Galliformes). Bulletin of the Florida State Museum 8(3): 195-335. PDF or JPEG fulltext
- Carboneras, Carles (1992): Family Anatidae (Ducks, Geese and Swans). In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (editors): Handbook of Birds of the World, Volume 1: Ostrich to Ducks: 536-629. Lynx Edicions, Barcelona. ISBN 84-87334-10-5
