Research on the interspecies relationship between brown bears and sika deer

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06833
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 45040:Ecology and environment-related
• Research Institution: Hokkaido University
• Principal Investigator: Shimozuru Michito 北海道大学, 獣医学研究院, 准教授 (50507168)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: ヒグマ / エゾシカ / 種間関係 / 食性 / DNAバーコーディング / 安定同位体比分析

Outline of Final Research Achievements

This study aimed to clarify positive and negative effects of sika deer increase on brown bear ecology. We collected brown bear scats and hair samples from the two areas in the Shiretoko Peninsula, the Shiretoko Cape (middle abundance of deer and bear) and the Rusha area (high abundance of deer and bear). Then, we investigated how differences in deer density affect food habit of brown bears, by use of scat analysis, DNA barcoding analysis, and stable isotope analysis. Scat analysis suggested that bears in the Rusha area prey on newborn fawns in June more frequently. However, DNA barcoding analysis indicated that bears in the Rusha area have less access to grass plants (e.g., Apiaceae) that bears prefer, and feed on young leaves of woody plant as an alternative. This suggested that brown bears in the Rusha area may have adopted to vegetation that has been damaged by deer, by changing their foraging ecology.

Free Research Field

野生動物学

Academic Significance and Societal Importance of the Research Achievements

エゾシカは北海道において30年間で急激に生息数を増加させ、その採食行動により森林・草原植生に深刻な悪影響を及ぼしているが、その影響がヒグマという他種にも及ぶことが本研究に初めて明らかになった。本研究結果は、ヒグマとシカの間に「食う／食われる」という単純な関係にとどまらない種間関係が存在していることを示すものであり、今後の野生動物の保護管理の在り方を考える上で重要な学術的／社会的意義を有する。