Mongolian Gull L.(?) mongolicus
January 24th 2003 Choshi Chiba Japan
This individual has really nice characteristics to be a Mongolian Gull, especially 8 black-marked primaries, black-marked long bill, and general structure. But its rich winter mottling around the neck might be unusual.
Note the powerfully-built body. The deep chest seems to hint the neck is long.
The Mongolian Gull with 2 Vega Gulls
Note their bill/head structures.
A Vega Gull (left), and the Mongolian Gull (right).
The red gonydeal spot of the Mongolian Gull does not reach upper edge of lower mandible.
The wing has 8 black-marked primaries. And the pattern of the underside P10 differs from Caspian Gulls.