Abstract
We recorded the first breeding record of black-tailed gulls Larus crassirostris in TokyoBay in 2015, and again in 2016. On 18 June 2015, chicks were observed in a nest constructed on a collision-barrier protecting the pier support of a railroad bridge in Tokyo Bay. In 10 May 2016, two nests with 3 eggs were observed at the same site and an additional 10 to 20 nests were estimated around the original site. Chicks were observed on 18 May 2016, and 16 juveniles were counted on 24 June 2016. Based on the previous breeding records in Tokyo, black-tailed gulls have moved their breeding site from inland areas to more seaside areas, and have now started to breed in Tokyo Bay.
