26/01/2012
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The right White-fronts

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This immature White-fronted Goose photographed on Midway Atoll, Hawaii, is probably one of the two smaller American subspecies, but assignment of wintering birds has obscured the species' true taxonomy. Photo: Forest and Kim Starr (commons.wikimedia.org).
This immature White-fronted Goose photographed on Midway Atoll, Hawaii, is probably one of the two smaller American subspecies, but assignment of wintering birds has obscured the species' true taxonomy. Photo: Forest and Kim Starr (commons.wikimedia.org).

A taxonomic revision of all the White-fronted Goose subspecies has resulted in a new form being named.


While the taxonomy of the two Palearctic subspecies of White-fronted Goose seems straightforward, the North American forms have been in some confusion until recently. A new paper has revised the American forms into three subspecies out of the four named forms, in the process naming a new subspecies.


Along with Greenland and European White-fronted Geese (Anser albifrons flavirostris and A a albifrons, respectively) , three other subspecies are now considered valid: elgasi, which breeds in the Cook Inlet area of Alaska and winters in northern California; gambelli, which breeds across Alaska and Arctic Canada, wintering in central USA and northern Mexico; and the new subspecies, sponsa, which breeds in western Alaska and winters in western Mexico.  

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The new taxon averages smaller in biometric measurements than the other two, but useful field criteria for its identification are not yet established.


The former subspecies frontalis, named from western Alaska and possibly eastern Asia, has been found to be invalid and a synonym of gambelli, and albicans, named from east Asia, has been synonymised with the nominate form.


During the course of the study, it was found that all named subspecies had been assigned names on the basis of wintering specimens of often indeterminate origin. This is the first complete taxonomic rearrangement, and is based on samples from known breeding populations, reinforcing its accuracy.


Reference
Banks, R C. 2011. Taxonomy of Greater White-fronted Geese (Aves: Anatidae). Proceedings of the Biological Society of Washington 124: 226-233 doi: 10.2988/11-14.1