Albert Village Baltic, 30th July 2015

2cy michahellis (foreground): the subject
2cy fuscus (background): the photobomber

Lying in bed, scrolling through the 400+ images I'd taken on my phone at Albert earlier in the day, I suddenly noticed an almost complete set of 2nd-gen primaries on a spread wing in the background of one of the pictures. I'd been photographing a flapping 2cy mich, but beyond it, at the back of the flock, about half a dozen shots showed a dark-looking 2cy gull having a stretch and a flap, then it drifted out of frame.
I zoomed in, I went back and forth across the handful of shots, and it all looked right for fuscus - another late July 2cy Baltic Gull! The primaries were all 2nd-generation, confirmed as such by the presence of tiny mirrors on P10, a feature not infrequently seen on Baltics, with the exception of P1, which was a half-grown 3rd-generation feather, the tiny white tip peeping out from under the coverts. The secondaries were the now-familiar neat line of new, broadly white-tipped feathers, and the greater coverts were complete too, looking a bit worn and brown, but both these tracts lacked the moult gaps of virtually every other 2cy present. The lesser and median-coverts show a bit more variation, with a few darker, presumed newer feathers present, but all appeared to be plain or only simply-patterned, unlike the anchored and barred equivalents on nearby 2cy LBBs.

Further details were difficult to detect, but the bill looked markedly two-tone, with a pinky base and dark tip, and the legs looked pink too. The iris appeared to be dark, and the underparts whitish with some streaking around the neck-sides. The tail showed extensive dark in the tip, but again detail was non-existent in the images, and moult appeared to be nearly complete. This combination further indicated that it was indeed a 2cy, and in that state of wing moult, any other ID options seemed unlikely.
Just wish I'd seen it!