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Wednesday, 23 September 2009

Taxonomy of 'Greater White-fronted Goose'

Lee:

I've pasted below the Taxonomy summary for Greater White-fronted Goose from our book "Birds of Nebraska", Univ Nebraska Press, 2001 (Sharpe, Silcock, Jorgenson).

Hope this is of some help.

Ross

Ross SilcockP.O. Box 57Tabor, IA 51653New Zealand Land and Pelagic Bird Tours http://www.rosssilcock.com

Taxonomy:
Taxonomy of this species in North America is in a confused state (for a discussion, see Banks 1983). It is generally agreed that the most numerous subspecies, breeding on arctic tundra from northeastern Siberia eastward to Hudson Bay, is A. a. frontalis (AOU 1957; Ely and Dzubin 1994). Most frontalis migrate through Nebraska to winter in southeastern Texas and northeastern Mexico, although southwestern Alaska breeders migrate along the Pacific Flyway (Ely and Dzubin 1994).

Some authors (Palmer 1976) use the name gambelli (the case for spelling this name gambeli is made by Banks 1983) for birds breeding in North America (except for southwestern Alaska) and wintering in Texas and Mexico. This name was first applied by Hartlaub (1852) to large, dark individuals collected during winter in Texas and thought to be representative of interior North American White-fronted Geese. However Swarth and Bryant (1917) used the name gambelli for the large, dark birds wintering in California as they assumed that, because these birds were rare in California, their main breeding range was eastward in Canada and thus they were the same as the birds described by Hartlaub (Banks 1983). Delacour and Ripley (1975) named the California birds A. a. elgasi (Tule Goose) on the assumption that they were the westernmost of 2 taiga-breeding populations distinct from the vastly more numerous frontalis, a tundra breeder, and gambelli for the eastern birds.

The western and eastern taiga-breeding populations use separate breeding, migration, and wintering areas (Palmer 1976) with minimal crossover between flyways (Ely and Dzubin 1994), and so a case can be made that they are genetically isolated from each other. Very little is known about the eastern population, but it is thought to breed near the MacKenzie River delta (Palmer 1976).

Some current authors (Banks, Ely, pers comm) believe these birds to be within the range of variation of frontalis and thus not separable from them. There have been sightings of large, dark ("chocolate-colored") White-fronted Geese in the North American interior (Nick Lyman, Martin Reid, pers. comm.) which may be referable to gambelli (per Hartlaub). A large, dark individual was with a flock of 400 in Hamilton Co 30 Mar 2003 (JGJ).

Of interest are band recoveries in Kansas and south-central Texas in the early 1980s of Tule Geese banded in the Pacific Flyway; these recoveries (4 out of about 300 birds banded) suggest a crossover of migrants from the Pacific to Central Flyways of about 1% (Ely, pers. comm.)