Status of Seabirds Breeding in Hokkaido.

Abstract

The historic and present status of seabirds in Hokkaido is summarized, based on published and unpublished data. At least 12 species breed in Hokkaido. The breeding pairs of seabirds in recent years in Hokkaido are estimated as follows: Common Murre (Uria aalge) <10; Tufted Puffin (Lunda cirrhata) 15; Spectacled Guillemot (Cepphus carbo) 100; Ancient Murrelet (Synthliboramphus antiquus) <20; Rhinoceros Auklet (Cerorhinca monocerata) 300, 000; Slaty-backed Gull (Larus schistisagus) 10, 000; Black-tailed Gull (Larus crassirostris) 30, 000; Red-faced Cormorant (Phalacrocorax urile) 25; Japanese Cormorant (Phalacrocorax capillatus) 3, 000; Pelagic Cormorant (Phalacrocorax pelagicus) 10; Streaked Shearwater (Calonectris leucomelas) 120; Leach's Stormpetrel (Oceanodroma leucorhoa) 900, 000. The present status of the Long-billed Murrelet (Brachyramphus perdix) is unclear. The colony size of Common Murre shrank with annual decreasing rate of 12.2% (1938-80)-26.6% (1981-94) on Teuri Island. It has decreased 24.8% annually, and it has not been observed on Moyururi Island since 1985. The Tufted Puffin and Spectacled Guillemot decreased 9-15% annually during the last 30 years. The Slaty-backed Gull increased 11.0% annually (1963-95) on Teuri Island, and 8.5% annually (1972-93) on Yururi Island. Black-tailed Gull increased by 5% annually (1987-2000) on Rishiri Island, but decreased on Teuri Island during the 1990's. The Japanese Cormorants increased by 5-9% annually on Teuri and Yururi Islands. Its number increased at annual rate of 6.4% during 1959-86, but decreased at annual rate of 10.4% during 1987-96 on Moyururi Island. At 12 of the 14 surveyed colonies predation by gulls and/or crows were reported, and disturbances caused by introduced rats and cats was reported at five colonies. Although most of the colonies are legally protected, few conservation programs have been effectively conducted. Seabird mortality by fishing nets was reported around six colonies, but protective measure for seabirds has not been taken. We here propose, therefore, non-fishing sea areas for seabird protection around such breeding islands.