Images A through L have been cropped and sharpened, with images F and G also being brightened slightly due to under exposure as the result of heavily overcast skies at the time of shooting.  Images P through U have been cropped only with no sharpening.  All images are otherwise un-edited, and I feel portray the bird very accurately.  Images A-L were taken with a Nikon Coolpix 995 attached to a Kowa TSN-824 scope, and images P-U are stills lifted from video obtained with a Sony DCR TRV-330 camcorder.  

Below are a few thoughts regarding the bird and its depiction in the images, and all comments regarding plumage features refer to first year birds in juvenal plumage.
 

A

B

Images A and B depict each side of the bird as it rests on the water.  These show that it is relatively symmetrical in plumage with neither side being noticeably different than the other.  It also shows that the attitude of the bird, posture and the way it holds its feathers, can affect the appearance and apparent structure.  The bird looks larger-billed and flatter-headed in image B to me.
 

C

Image C portrays the bird standing.  It appears chunky and very short-legged which I feel are strong features for glaucoides.  The bird is long-winged, with the tip of P-7 falling roughly even with the tail tip.  In this image, the dark center of P-10 is covered by the pale tip of P-9. 
 

D

E

Images D and E show how pale and uniformly colored the bird appears dorsally, and how extensive the pale edges of the primaries are.
 

F

G

Images F and G show the bird from a nice angle, and Image G is a close-up cropped from F.   It shows plumage detail including wear to the scapulars and retrices which would be expected at this time of year. There is a relatively solid area of pigment in the center of one of the tertials, and the pigment in the retrices appears to be relatively solid and generally lacking internal mottling in the distal area visible.  I think the solid area in the center of the tertial and the relatively solid color of the tail dorsally may be due to thayeri influence.  I believe many Kumlien’s Gulls in juvenal plumage show tail bands to some degree, but generally appearing more mottled and less solid.  The remainder of the plumage looks good to me for kumlieni.  I believe the extent of pale edging to the primaries is too extensive for thayeri given the condition of plumage, and that wear alone can’t account for the overall lack of pigment in areas where it should be shown by thayeri when still showing nice internal markings to the plumage. Feather areas which lack pigment tend to wear more quickly than darker feathers, and the pale edges to the primaries may have been more extensive earlier in the season.  They appear to be at least as extensive in the images obtained by Brainard Palmer-Ball on 25 January when the bird’s plumage was somewhat less worn.  I’ve seen a few photos of worn birds that were presumably Thayer’s, and that were almost a totally washed-out white, but the extent of wear was extreme in those birds.
 

H

Image H shows the ventral surface and somewhat richer coloration compared to the upperparts.  I believe the underparts of both thayeri and glaucoides are generally richer and darker than the upperparts in first year birds, and should remain so later in the season  due to less bleaching than in the exposed upperparts.  The white-winged look to the underside of the primaries is evident.
 

I

J

Images I and J show close-ups of the plumage, including the upper surface of the tail from different angles.
 

K

Image K shows the bird’s left side from the front.  A small area of richer coloration is visible just under the chin and along the front of the neck.  I think this may be due to being somewhat protected from bleaching, and is a clue to what the overall look of the bird was earlier in the season.  A diffuse but somewhat solid area of pigment is visible in the center of a tertial, and the visible tail feather shows some barring.
 

L

Image L shows the underside of the tail including coverts.
 

M

N

O

Images M-O are stills lifted from video obtained through my scope as the bird bathed.  They show both surfaces of the tail which appear relatively solidly colored with some barring.  Some of the barring can be attributed to the coverts showing through.
 

P	Q	R
S	T	U

Images P-U are stills lifted from video depicting the bird in flight from various angles.  I believe the bird looks very good for glaucoides in flight, particularly the overall uniform coloration.  I think the amount of pigment in the primaries and secondaries is very much within the range of kumlieni.  The tail band shows a little differently here, appearing more solid toward the center and more diffuse distally and basally.  I believe the broad but relatively pointed wings look very good for glaucoides.

I initially felt that the bird was a Kumlien’s Iceland Gull, but after consideration, hesitantly backed up a step thinking the bird may be an intergrade.  The features that I considered here are the relatively diffuse but solid areas of pigment in the center of some tertials, and the relatively solid tail band.   These features may be within the accepted range of variation for kumlieni, and the bird may well be a “good” Kumlien’s Iceland Gull.  I personally can’t rule out thayeri influence due to lack of experience with variability in kumlieni.  I don’t believe the bird is a Thayer’s though, that is unless they’re all Thayer’s, and represent clinal variation within a single species.