Heuglin's Gull L. heuglini taimyrensis
January 5th 2001 Choshi Chiba Japan

This is a typical small taimyrensis resembling Lesser Black-backed Gull L. (f) graellisii.  But its molt is obviously delayed compared to LBBG, and  still keeps 3 old primaries.   The white spots of new primaries are smaller than that of most Vega Gulls.
The right bird  is  a darker Vega Gull,  probable nominate vegae. Compare their mantle grey and  leg colors.
The leg color looks like intermediate between Vega and Black-tailed Gulls. Legs of LBBG seem to be purer yellow on average. But this also may get yellower in spring. The right bird in this photo is an average or a little paler vegae, and might be birulai