A gull seen on Japanese coasts through much of the year, with a catlike call.
Adults have a black tail band and yellow legs; the yellow bill has red and black markings near its tip.
At Kabushima, Hachinohe, Black-tailed Gulls fed at sea and on land during incubation and hatching. A GPS study recorded anchovies and cuttlefish at sea, and feeding visits to rice fields, fish or meat processing sites and markets, and private homes. Video loggers and stomach samples also documented human-related food. Trips to sea covered larger ranges; inland trips were more direct and shorter.
A separate 2012–2023 breeding monitor found 1.57–2.16 eggs per nest in May. In early July, the number of chicks seen per egg counted in May ranged from 0.01 to 0.29 among years.
Japan Red Data Book (5th edition) · Vulnerable (VU) · Japan, national species assessment
Japan’s 2026 fifth Red Data Book lists the Black-tailed Gull as Vulnerable (VU). Of the eight breeding sites included in the national assessment, two had disappeared. Counts at the six remaining sites were 16–53% lower than about ten years earlier; the average decline across all eight sites was 42%. The assessment names predation by cats, rats, foxes and White-tailed Eagles, falling fish supplies and human disturbance among continuing pressures. A separate analysis estimated that the species’ population index in 2015 was 28% of its 1980 baseline.