I have just finished going through the hundreds of photographs I took at Chesil Cove back on January 7th this year. Here is another large gull that got my attention. I managed to grab a few, very similar frames of it. I was struck at the time by the contrast between the gull's white rump and all black tail. The mantle is also a slightly darker grey than our usual Herring Gull L. a. argenteus. I suspected the bird maybe a 3rd calendar year Yellow-legged Gull, as it does appear quite bulky. The rather prominent, pale, inner primaries would however appear to rule out 'most' Yellow-legs. The black tail is reminiscent of the pictures we see of imm. American Herring Gull, but the mantle is almost certainly too dark.
OK then, to me the bird doesn't look much like our 'bog standard' Herring Gull L. a. argenteus; and for some reason I completely overlooked the possibility of it being a 'nominate' L. a. argentatus.
I recently invited comments about this bird. Here is a reply received by gull expert Lou Salomon from Stuttgart, who 'loosely' suggests that the bird may be the latter.
"it's a 3cy herring gull; most 2nd winter michas (Yellow-legged Gulls) are more advanced in the amount of grey feathers (esp. usually showing a more or less complete median covert row by midwinter), head usually is white, bill yellow, and such an almost black tail is also rare in 2nd cycle YLG. the dark head, bicoloured but not yellowish bill, all brown upperwings and black retrices fit much more an argentatus (poss. nominate)."
OK, when Lou says 'fit much more an argentatus' he means of course Herring Gull race unspecified... he doesn't say it is a nominate. Because it looks and feels so different, and did so amongst hundreds of argenteus on first sight.. I would like to believe it is; but, then again I would, wouldn't I!
Thank you Lou. To everyone else: answers on a postcard please.