Slaty-Backed Gull L.schistisagus
December 11th 2003 Choshi Chiba Japan

A quite dark Slaty-backed Gull. But this species does not always look like this, because of variations and light conditions.

A paler Slaty-backed Gull under a similar light condition.
Note the quite typical facial impression, shortish wings, and general structure, for the species. The P10 is still a little short.

A different paler Slaty-backed Gull (left) with a Vega Gull (right).
Note that the mantle shade is not extremely dark, and apparently somewhat approaches the tone of the Vega Gull. I could not find out any other features that might suggest vegae-influence. Such birds tend to be easily misidentified as Vega Gulls, especially in summer. In summer Japan, Vega Gulls actually seem to be almost entirely absent.