(Presumed) Caspian Gull L. cachinnans
January 24th 2003 Choshi Chiba Japan
The white head and black-marked straight bill looked significant. But, it sat tight and never stood up while I was watching it. So I could not see its leg color and wing-pattern. But, I noticed later that this bird seemed to be the same bird as the presumed Caspian Gull.
With 2 Vega Gulls. Note the difference of their facial impressions.
A presumed Mongolian Gull on the same day.