Home Range and Habitat Use of Brown Bears in the Southwestern Oshima Peninsula, Hokkaido

Abstract

Movement, home range, and habitat use of 10 (7 M and 3 F) brown bears (Ursus arctos yesoensis) were investigated by radiotracking in southwestern Oshima Peninsula, Hokkaido, from May 1987 through May 1990. The annual home-range size was 28.1-39.1 km2 for 1 female. Male home-range size was larger than that of females, although no males were monitored throughout the year. Lower deciduous natural forest areas such as beech-oak (Fagus crenata)-(Quercus monoglica var. grosseserrata) forest and maple-linden (Acer mono)-(Tilia japonica) forest were used by bears intensively, but subalpine areas such as sasa-birch (Sasa kurilensis or S. senanensis)-(Betula ermani) forest and sasa community were rarely used and usage was restricted. Food availablilty could influence the habitat selection by the bears. Int. Conf. Bear Res. and Manage. 9(1):319:325 Hokkaido brown bears have been killed indiscriminately for more than 120 years. Especially during the period of 1966 through 1989, the spring prophylactic killing system was in force, and many bears were killed as pests and as game animals. Forest and field areas have been developed without considerations of bear habitat maintenance. As a result of these pressures, conspicuous extinction or near extinction had occurred by the 1980s in northern Hokkaido (Aoi 1990) and in areas such as the Shakotan Peninsula and the Yoichidake-Eniwa mountain area (Hokkaido Government 1986). However, recent bear damage to livestock and crops still occurs in other parts of Hokkaido (Hokkaido Government 1986). It is obvious that with the control kill alone, damages will continue to occur until the bear population drops to near extinction. Since mid 1970, about one-fourth of the total brown bear damage in Hokkaido has occurred (annually) in the Oshima Peninsula (Hokkaido Government 1986), which occupies only about 9% of the island. As this area is a peninsula, characterized by having a very long boundary between bear range and human residential areas, troubles and conflicts between people and bears are apt to occur. Moreover, habitat development on the Oshima Peninsula could have a major influence on bear habitat and population maintenance on Hokkaido. Biological information such as brown bear home range and habitat use is required for proper habitat management. The first successful brown bear radio-telemetry study in Hokkaido, Japan, was initiated in southwestern Oshima Peninsula in 1987. In this paper, I present preliminary information on movement, home range, and habitat use of Hokkaido brown bears in the deciduous forest of this area. I thank K. Maita and S. Kojima for their devoted field assistance. I thank also M. Yoneda, H. Abe, T. Aoi, H. Kudo, and T. Akasaka for their helpful advice and suggestions. Y. Maruko, A. Kishikawa, J. Yamazaki, T. Tsuizuki, G. Suzuki, N. Sato, T. Sato, and K. Takahashi, who are the members of the Hokkaido Hunting Society, kindly cooperated with the study. T. Tsubota, K. Yamamoto, Y. Kamada, and the members of the Brown Bear Research Group of Hokkaido University also provided devoted field assistance. Y. Sawamura and K. Kudo provided assistance in aerial radio location. The Matsumae District Forestry Office of Hokkaido also gave facilities for investigations. K. Kanagawa cooperated with the English. This research was partly funded by the Japan Environmental Agency. Asahi Broadcasting Co., Iwanami Productions Inc, and Tokyo Broadcasting System Inc. also provided financial assistance.