Heuglin's Gull Larus heuglini
December 2nd 2001 Choshi Chiba Japan
Vega Gull on the left, and Heuglin's Gull on the right.
Note how the Heuglin's Gull resembles Lesser Black-backed Gull well.
Another individual found at the same time (right) , and a 2nd winter Slaty-backed Gull (left). Note the smaller size, light-built structure, delicate smallish bill.
Its inner primaries do not form distinct 'window', though it is not completely dark. And a dark greater covert-bar is visible.
Right to left: Heuglin's Gull, Slaty-backed Gull, Vega Gull.