A return trip to the Windsor Landfill produced immense numbers of gulls peaking at about 1pm with around 6,000 birds present. The first ninety minutes produced only two species (American Herring and Great Black-backed Gulls) but after 12:30 things began to pick up with a new adult Kumlien's Gull and two first-cycle Lesser Black-backed Gulls.
Just before 2pm I came across this beast! A large, rather pot-bellied first-cycle bird with a distinct frosty tone and a curious cinnamon-buff appearance to much of the upperparts. Head and bill profile looked distinctly different to most smithsonianus present with a rather flat crown, long sloping forehead, long lores and long, heavy bill.
The Ujiharas, creators of the Japanese Gull site, kindly commented that almost all the features shown by this bird could be within the range of a first-cycle Slaty-backed Gull. However, the pink based bill would only be shown by a minority of birds at this time of year and most Slaty-backed tend to show a more drooping bill. They also that felt the uniform neck pattern wasn't particularly good as most first-cycle Slatys tend to show more spotted or streaked neck sides. I'm very grateful for thier comments in any event.
Looks like a bird than might be beyond a certain identification for the time being, but it was certainly one to get the heart beating faster in the field!
unidentified first-cycle gull - compared with the American Herring Gull (left) much larger and bulkier with broad whitish tips to the tertials and greater coverts. Primaries distinctive being brown, not blackish-brown, with very neat whitish tips and narrower fringes. Pale bleached head and hind-neck with noticeable but uneven 'mask'.
unidentified first-cycle gull - not too difficult to pick out from the crowd being larger than most American Herring Gulls plus bulky with warm cinnamon-buff tones and rather even, 'velvety' underparts. Overall appearance, not unlike a huge, warm-toned Thayer's Gull.
unidentified first-cycle gull - large, bulky and distinctly frosty looking with pale hind-neck and subtly streaked lower neck.
unidentified first-cycle gull - first of several digibin flight shots. Rather subtle and uniform in flight, again recalling large Thayer's to some extent. Quite densely but finely barred rump. Fairly narrow secondary bar blending into inner primaries. Inner primaries forming pale but diffuse panel showing 'two-toned' effect merging gradually into outer primaries with no sharp contrast between inner and outer primaries.
unidentified first-cycle gull - Pale inner webs of primaries continuing gradually to outer most primaries showing weak 'pearls' effect. Cropped detail of the primary pattern shown below.
unidentified first-cycle gull - Pale inner webs of primaries continuing gradually to outer most primaries showing weak 'pearls' effect. Rather translucent underwing again recalling Thayer's Gull.