The black-tailed gull (Larus crassirostris) is a medium-sized (46 cm) gull, with a wingspan of 126–128 cm. The bird is resident in East Asia, including China, Taiwan, Japan and Korea. It is a vagrant to Alaska and northeastern North America.It has yellow legs and a red and black spot at the end of the bill. This gull takes four years to reach full adult plumage. As the name suggests, it has a black tail.