Effects of vegetation decline due to sika deer on the foraging ecology and occurrence of Japanese black bears

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05672
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40010:Forest science-related
• Research Institution: University of Hyogo
• Principal Investigator: FUJIKI Daisuke 兵庫県立大学, 自然・環境科学研究所, 准教授 (30435896)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: ツキノワグマの食性 / 糞分析 / シカによる森林衰退 / モウソウチク / カキノキ / 液果類 / 近畿北部西側個体群

Outline of Final Research Achievements

A study was conducted on black bears (hereafter referred to as “bears”) in the Nourthen Kinki region population for elucidating the effects of forest vegetation decline caused by Japanese deer on the bears' use of food resources.A total of 280 samples of bear fecal material were collected by field survey during the period 2021-2023. The collected samples were analyzed for contents and their composition. The results showed that, compared to other local populations, bears in the study area were less dependent on phytotrophs present in the forest, especially dwarf bamboo. In addition, they were found to be highly dependent on bamboo shoots and Japanese persimmon, which are present near human settlements. Furthermore, the fall diet was less dependent on hard nuts and more dependent on fleshy fruits.

Free Research Field

森林生態学

Academic Significance and Societal Importance of the Research Achievements

本研究から、ニホンジカによる森林の下層植生衰退によって、ツキノワグマの食性が、集落周辺に存在する人為的餌資源（孟宗竹の筍、柿）への依存度を高めている可能性が示唆された。また、クマの秋の食性は、ブナ科堅果に強く依存するものと既往研究では考えられてきたが、本研究では、堅果ではなく、液果類に強く依存しており、その豊凶によって出没が左右されていることが示唆された。さらに、暖温帯域に生息するクマの食性は、冷温帯域のクマと異なる可能性も示唆された。これらの結果は、今後のクマの集落周辺への出没対策やシカの高密度生息域でのクマの生息地管理を考えるうえで有用な知見といえる。