Observations on sea birds of Moyururi Island, eastern Hokkaido

Abstract

Observatins of sea-bird colonies made in May and July, 1959, and June and July, 1960 on Moyururi Island off southeastern Hokkaido, are reported. The island measures 3km. of costal lengh with elevation of 30m. from the sea level. It is a bare and uninhabited island. Twenty-six species of birds including 12 species of sea birds were recorded. Of the sea birds, 7 species breed on this island (Table 1). There were about 120 individuals of Phalacrocorax capillatus, about 70 P. urile, about 400 Larus schistisagus, about 200 L. crassirostris, 29 Uria aalge, about 160 Cepphus carbo and about 230 Lunda cirrhata. Cerorhinca monocerata could not be encountered because of the nocturnal habit. Breeding sea birds had eggs during May and June, and young during June and July.The colonies of Phalacrocorax urile, Larus schistisagus and Lunda cirrhata on this island form the southern limit of their breeding range. In Uria aalge Ko-jima in the Japan Sea side and Moyururi Is. in the Pacific side, are the southern limis. Therefore Moyururi Island is very important ornithogeographically.