'Taimyr Gulls' Larus heuglini 'taimyrensis'
March 25th 2011 Tokyo Imperial Palace Japan
The mantle shade was very similar to Vega Gulls, but the structure was obviously slimmer and lighter.
Note that the black markings on wings are well-extended, and reach P3, and the single small mirror. But the white marks between black and gray ('moon') on P7-P5 are more prominent than in heuglini.
Another individual on the same date, closer to heuglini. The mantle was darker than in individual 1, but obviously paler than a Slaty-backed Gull that was present nearby. I temporarily treat this as 'taimyrensis' here, but on the other hand suspect some pale heuglini might look almost identical to this.
No 'moon' on P7 and 8.