Leusictic kamtchatka gull

 At first glance, I imagined ivory gull, but soon I could figure it was an leusictic mutation of kamtchatka gull (Larus canus kamtschatschensis) which most 'common' of the common gull complex L. canus ssp. wintering in Korea. I'll go for Russian, Mew, and nominate Common gull(L. canus canus) this winter.

I'm just stuck in library and office chair nowdays, making me sick of going out for some quest.