bird 11. Slaty-backed Gull, subadult, Choshi, Japan, 7 March 2012.
A pale bird, but not quite adult yet judging from extensive black
on bill, and dull iris. Black wingtips, and entirely blackish outer
web of P10 do not suggest influence of Glaucous-winged Gull.
Blotchy head markings and thick body with short wing projection
do not really recall Vega Gull either.