Beddington White-winged Gull

[AndyB]

Lee Evans' email to various listservs included a link to photos on Birdforum of this gull:

What is considered to be the juvenile 'white-winged gull' first seen at Queen Mother Reservoir (Berkshire, England) in February and then subsequently at Stewartby Lake (Bedfordshire) and Willen Lake (North Buckinghamshire) in early March and at Rainham Marsh (Essex) on 12 & 16-18 March reappeared at QMR two nights ago and was at Beddington Sewage Farm (Surrey) today (see images linked with the thread below)

http://www.birdforum.net/showthread.php?t=139630

This individual has dramatically changed its plumage between February and now and after writing it off as a hybrid back then (probably with North American Herring Gull influence), its appearance now far more resembles GLAUCOUS-WINGED GULL.

I would be most grateful if those of you very familiar with GWG would have a look at today's images and comment on whether this resembles West Coast birds at this time of year. It has always seemed too small in terms of structure and jizz

This winter has seen an exceptional influx of Arctic gulls into Western Europe, including record numbers of both Iceland and Glaucous Gulls in Iberia, the majority of which arrived just after a fierce winter storm arrived from the NW Atlantic (it also displaced several Snowy Owls and Gyrfalcons, Ivory and Ross's Gulls and a number of North American ducks, a Killdeer and an American Coot. We have already had an adult Glaucous-winged Gull in Cleveland in early January.

The Beddington bird's plumage looked impressive at first glance for 1st-winter Glaucous-winged but Peter Alfrey's larger photos seem to portray a slighter bird and bill perhaps indicating (as has been suggested) some sort of hybrid? http://peteralfreybirdingnotebook.blogspot.com/

Plumage looks decent for Glaucous-winged but structurally less convincing (especially size and shape of bill): http://surfbirds.com/albums/showgallery.php/cat/601

Hybrid American HerringxGlaucous-winged we'd expect to show more of a dark tail band?

Southern California has also had a bit of a white-winged gull event winter this year too with excellent numbers of Glaucous and significantly more Glaucous-wingeds than usual. Seawatching reports this week have revealed flights of Glaucous-wingeds heading north.

[JanJ]

Now, the dificulties involved when attempting to identify strange looking LWHG, is the ability to judge whether it´s an aberrant individual or a hybrid. Most of the time this is a nearly impossible task since mixed characters appears more or less obvious in one individual. One such hybrid that often, but not always, shows rather clear features of both species is Glaucous Gull x Herring Gull.

http://www.elisanet.fi/hj.koskinen/LarhypXarg2cy_Koukku20090418.html

and probably this one:

http://www.tarsiger.com/gallery/index.php?pic_id=muu1200178602&lang=eng

But what do you make of this one?

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=26914

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=26913

or this one?

http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=15025

The subject gull doens´t strike me as a Glacucous-winged at all, more of Herring structure in there. The pale wings and uniformly patterned body with washed-out coverts and tail - which seems to be nearly all dark - suggests one of the northern white-winged gulls, except perhaps the tail pattern, question is which? As have been mentioned, Glaucous x Herring seems to be one of the better choices. Would that be because we see the expected bill shape/pattern - structure or/and plumage features associated with these species - or is it a more convinient choise, based on the fact that we can´t deal with such birds on an identification basis?
Anyway, I can´t identify the Beddinton gull other than a possible Glaucous x Herring, being more certain of the Herring influence.

JanJ