Although Oshima-Ohshima, lying 50km off Matsumae in Hokkaido, is Japan's largest uninhabited island, its existence is largely unknown. It is the northern most breeding ground for the Streaked Shearwater in Japan. From the Edo period to the present, the Streaked Shearwater has survived volcanic eruptions, capture by man, direct predation by the brown rat, and indirect pressure by the destruction of its nests by the Japanese white rabbit. It is now, however, on the brink of extinction.