Saturday, 26 June 2010

Glaucous-winged Gull at Beddington Farmlands?

Photo by Garry Messenbird
Photo by Kevin Guest

CASE FOR: A worn first-summer female Glaucous-winged Gull: A relatively fine bill and herring gull like structure consistent with size variation of GWG. All dark tail (darkest part of bird), heavily barred upper and under-tail coverts, worn dark mantle/scaps and overall uniform bird with bright pink legs and all dark bill consistent with GWG. The eye also appears in some photos to be high in the head. The pale tips to the uniform (with the rest of the bird) primaries is a typical function of ware. Some similar birds are shown in the post below.
CASE FOR: A first summer 'west coast (Glaucous-winged Gull) hybrid': The fine bill and short secondaries are structural inconsistencies with GWG. The combination of these two atypical features is very unusual (1.4% of birds in a quick analysis). The herring gull like structure to the Beddington bird could indicate the presence of American Herring Gull genes suggesting a GWGxAMHG or even a GWGx(AMHGxGWG). There is an inconsistency of acceptable variation within GWG between published literature (scientifically approved) and the Internet (uncensored). There are unanswered matters concerning the full nature of the extensive hybrid swarms on the west coast of North America and identification criteria for various hybrids and inter-species variation of this complex has not been adequately documented. Is it therefore impossible to rule out a hybrid with certainty/high degree of confidence?

Glaucous-winged Gull at Beddington Farmlands- similar specimens

Photos of specimens which recall structure an/or some plumage characteristics of the Beddington bird.

Glaucous-winged Gull at Beddington Farmlands links

Glaucous-winged Gull gallery:

Hybrid gallery:

Bird Forum discussion:

Discussion on Lee Evan's Blog:

The Same Bird?: