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Western Gull? Port Twonsend WA USA (1 Viewer)
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JANJ
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For my own edification, can you explain why? Looks to be a very close match to some Howell & Dunn photos of "Olympic Gull" juveniles (don't have it with me now, but can supply specific refs later). In any event, given possibility of back-crosses, there are even more possibilities than just a pure GLWG and straight hybrid--could also be 1/4 Western, etc.
Best,
Jim
Good point, fair question.
It is subtle, but in the examples in Howell & Dunn, note how the wingtips, secondaries and tail appear visibly darker than the upperparts. The dark wingtips and tail are also specifically mentioned in the caption to photo H1.5.
I am not convinced this is the case in the bird posted here. Its plumage appears dark allover (though this may be partly due to harsh sunlight perhaps, creating shadow effects on the underparts?).
Perhaps it is too dark for GWGull - but who knows? Noone is banding GWGulls up there in Alaska, so we do not have a full understanding of their variability.
In any case, dark 1st-cycle birds are sometimes seen in Japan (e.g. http://www23.tok2.com/home/jgull/020205/GW.html), far from Western Gull influence.
It is true, of course, that many backcrosses occur, and that these can have very little mixed genes left. The question that interests me most is: are there any features betraying their mixed ancestry visible still in such birds in the field - let alone in a single photograph ? If no evidence is visbile, I normally refrain from bringing up the issue of hybrids/backcrosses.
It is subtle, but in the examples in Howell & Dunn, note how the wingtips, secondaries and tail appear visibly darker than the upperparts. The dark wingtips and tail are also specifically mentioned in the caption to photo H1.5.
I am not convinced this is the case in the bird posted here. Its plumage appears dark allover (though this may be partly due to harsh sunlight perhaps, creating shadow effects on the underparts?).
Perhaps it is too dark for GWGull - but who knows? Noone is banding GWGulls up there in Alaska, so we do not have a full understanding of their variability.
In any case, dark 1st-cycle birds are sometimes seen in Japan (e.g. http://www23.tok2.com/home/jgull/020205/GW.html), far from Western Gull influence.
It is true, of course, that many backcrosses occur, and that these can have very little mixed genes left. The question that interests me most is: are there any features betraying their mixed ancestry visible still in such birds in the field - let alone in a single photograph ? If no evidence is visbile, I normally refrain from bringing up the issue of hybrids/backcrosses.
Thanks for the excellent explanation! I don't see any photos of GLWG in Howell and Dunn that are as dark as OP's bird; and the hybrid in 1.7 still seems like a very close match to my eyes for OP's bird, with similar lack of contrast between primaries and rest of plumage. But even H&D seem uncertain about the range of variation for GLWG--noting in photo 33.9 that the "left-hand bird is relatively dark, at (or beyond?) the extreme for a pure bird" (and this is a bird lighter than the OP's bird). The photo you linked to looks darker than the photos in H&D, and I presume we can be sure it's pure (?); but still not quite as dark as OP's bird to my eyes (though it's a close call!). So I guess I'm still unsure but leaning towards it being a hybrid or "partial" hybrid, but at least we all agree it's not a pure Western Gull!
Cheers,
Jim
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