Hi Doug- this is a tough one! I've studied Sibley and one hypothesis is that your bird is a hybrid Herring x Glaucous-winged based on the intermediate tones in the wing tips. The bill, buff feathers on upper wing and the tail band suggest a young bird, perhaps fledged the year before you saw it.
Looking at the very petite bill, small head, and short looking body, and taking into account the location, my first guess would be first year Mew Gull. The dark bill tip and the heavy tail band look right as well.
The one thing I'm struggling with is the primary pattern. The limited amount of black looks good for Mew, but the limited amount of white looks more correct for Ring-billed. Of course by range Ring-billed might not even occur there, so I could be floundering over nothing.
My vote is for a late first cycle Mew Gull. The bill is very dainty as stated. I like the leg and eye color also. I have seen many of these small gulls on the Northern CA coast in winter. And, this is an Alaska breeder. FYI, Mew Gulls are 3 year gulls (3 years to adult plumage).
I had a feeling I might be on shaky ground with the hybrid suggestion. The wingtips looked too light to me for a Mew but I did not the petit nature of the head and bill. On this last point, the bill, though petit, looks too big for a Mew. I have no experience with Mew but lots with Common Gulls in Europe.
However, I think Paul and Dan have con provide convincing arguments.
I had a feeling I might be on shaky ground with the hybrid suggestion. The wingtips looked too light to me for a Mew but I did not the petit nature of the head and bill. On this last point, the bill, though petit, looks too big for a Mew. I have no experience with Mew but lots with Common Gulls in Europe.
However, I think Paul and Dan have con provide convincing arguments.
Although I didn't dispute the ID (Mew Gull) I thought the aging was off, but didn't have any reference material with me. I've now looked through my gull guides & these support my view that this gull is a 2nd winter individual. Relevant features include:
Pale eye;
Mirror on outer primary;
Relatively 'clean' underwing/parts, as 1st year Mew Gulls are usually the most heavily marked at that age in comparison with both Common/Ring-billed Gulls;
1st year Mew Gull have heavily barred undertail coverts.
The tail band is highly variable in 2nd winter Mew Gulls, from dark spotting on just a few tails feathers to a full tail band.