Bear diets and human-bear conflicts: Insights from isotopic ecology

Bears, Ursidae, are considered omnivores, except for giant pandas Ailuropoda melanoleuca and polar bears Ursus maritimus. However, omnivory includes a wide range of dietary variation and trophic positions, making bear dietary ecology unclear. We inferred bear trophic positions from δ¹⁵N (‰) values and examined their correlation with diets reported in the literature, including frequency of human–bear conflicts (livestock predation and crop damage incidents). Overall, 15N signatures were consistent with diet estimates. Bear species with higher ¹⁵N signatures differed more from each other, including cases of large regional intraspecific variance, than bear species with lower ¹⁵N signatures. Bear trophic position and frequency of reports of human–bear conflicts were uncorrelated, suggesting that livestock predation by bears is an opportunistic behaviour rather than a response to food availability dynamics.