Mongolian Gull

The Mongolian gull is a large white-headed gull that closely resembles the Caspian gull, the Vega gull and the European herring gull, so identification needs careful study of the wing pattern and moult and, in young birds, of the wing and tail patterns. Males weigh 1.15–1.58 kilograms and females 0.85–1.1 kilograms. The mantle and wings are mid grey with black primary tips, distinctly darker than the European herring gull and slightly darker than the Caspian gull, but about the same as the Vega gull. (Wikipedia, general species account)

The species breeds in interior eastern Asia, primarily on large inland lakes, either fresh or saline, from the Altai Republic to Lake Baikal in central southern Russia, in northern Mongolia, and at Lake Khanka in northeast China. A small population also breeds on islands in the Yellow Sea west of South Korea, within the normal wintering area. In winter it migrates southeast to the coasts of Japan, the Korean Peninsula, eastern and southern China, Taiwan and northern Vietnam. (Wikipedia, general species account)