Relationships between intrusion of Japanese black bear (Ursus thibetanus japonicus) and Satochi-Satoyama environment in Numata City, Gunma Prefecture, Japan

摘要

Several factors are implicated in intrusion of Japanese black bears {Ursus thibetanus japonicus) into human living areas, and one of them is the deterioration of the Satochi-Satoyama environment. We analyzed the relationships between bear intrusion and Satochi-Satoyama environment in Numata City, Gunma Prefecture, to elucidate factors involved in bear intrusion. We classified the Satochi-Satoyama environment by land usage into six groups, namely, crop fields, paddy fields, orchards, fallow fields, wastelands and forest edge; their locations, planting condition, and management situation were investigated. Data of the Satochi-Satoyama environment quantified using the Geographic Information System and data associated with the bear intrusion sites within the area investigated were analyzed. The analyses were carried out macroscopically and microscopically on divided lots and bear intrusion sites. Macroscopic analysis revealed a positive significant relationship of bear intrusion with geographical complexity (P < 0.01) and the area ratio of orchards (P < 0.01). Microscopic analysis showed that the bear intrusion frequency increased significantly with orchards (P < 0.01) and on the forest edge with heavy tussock growth (P < 0.05). The results suggest that the influential factors in bear intrusions in the study area include geographical complexity and the presence of orchards and tussocks.