Slaty-backed Gulls Larus schistisagus
February 16th 2007 Choshi Chiba Japan
An individual showing narrower tail band. The wing coverts also show well-notched pattern.
Note that the dark parts of the wings and the tail are brownish, not blackish. And the short-winged overall structure is typical.
A dark-winged bird.
A pale-winged bird
A bleached bird.
A Vega Gull for comparison.
Note that the dark parts are strongly blackish in comparison with Slaty-backed Gulls.