Juv/1st winter Glaucous Gull Larus hyperboreus ?

This Glaucous Gull was observed by me on the Sea of Japan side on February 21.
The given impression was different from 'barrovianus'-Glaucous Gull on the Pacific Ocean side.
Especially, Jizz and Tail band were interesting.

With Ad Slaty-backed Gull.

With Slaty-backed Gull.

Primaries are white.

Note the blackish tail band.

With Ad and 3rd Slaty-backed Gulls.

With Ad Slaty-backed Gulls and 1w normal Glaucous Gull.

From Atuta Hokkaido Japan. February 21.