Boddingtoin Reservoir: search for Caspian Gull in the gull roost

The weekend's lengthy dose rain finally cleared away on Sunday afternoon, encouraging me to get out to Boddington again to see what the gull roost had to offer.  Arriving about quarter to four, the sun cast a strong yellow orange glow across the autumnal landscape, illuminating the gathering of gulls already assembled in the middle of the reservoir.  A quick scan through the flock revealed the vast majority to be black-headed gulls, but also good numbers of common gulls plus a few lesser black-backed and a couple of adult herring gulls.  These birds will have been out and about foraging across our landscape during the day, returning to the safety of the reservoir overnight before leaving very early in the morning.  It feels like quite a social gathering too - probably an interesting mix of gull "dialects" from across Europe!

I continue watching and counting for about forty minutes as waves of gulls arrive to roost, some departing as well, possibly heading for Draycote Water where there is likely to be a larger roost.  The black-headed gulls are hard to count, I estimate something like 4000.  Common gulls number over 250.

I'm hoping to find a Caspian gull, and eastern relative of the Herring, more elegant, with a slimmer but longer bill and distinctively pale head in winter.  One has been seen here recently but they are still pretty scarce locally, and very likely under-recorded.  A white-headed "herring-gull" type bird does stand out from the crowd.  It is a third winter - so not quite an adult (a smudge of darkness in the tertials and a dark marking on the bill).  I am now trying to convince myself this is the elusive Caspian: the head shape looks right (pear-shaped), the eye small and dark.  The light is failing so I take a few pics to check when I get home.

On the monitor screen, the images of the bird are a bit distant and too grainy to interpret any more detail. The field guides all point me in the direction of Caspian but I'm just not 100% sure - though feeling better informed for next time - hopefully a closer view in better light!