Notes on Gulls at the Mouth of Tama-river, from April, 1985 to March, 1986

Abstract

From April, 1985 to March, 1986, Black-headed Gull Larus ridibundus, Bonaparte's Gull L. philadelphia (a straggler), Herring Gull L. argentatus, Slaty-backed Gull L. schistisagus, Black-tailed Gull L. crassirostris and Mew Gull L. canus were observed at the mouth of Tama-river, which forms the boundary between Tokyo-Metropolitan and Kanagawa Prefectures. The main species were Black-headed and Black-tailed Gulls in this estuary. The Black-headed Gull was dominant in winter whereas the Black-tailed Gull replaced it from July to September. Other four species occurred only in small numbers.