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.