The relative abundance of crop and natural food influences crop consumption by brown bears

Many mammalian species now inhabit anthropogenic landscapes, and human–wildlife conflicts, particularly pertaining to crop damage, have become a significant issue. To develop more effective measures to limit crop damage caused by wildlife, it is crucial to identify how natural and anthropogenic food availability affect crop use by wildlife in the context of their feeding strategies. However, many previous studies have focused only on one side of the spectrum: either the availability of natural foods or that of crops. In contrast, this study examines how the availability of both acorns and crops affects the use of dent corn Zea mays by brown bears Ursus arctos in northern Hokkaido, Japan. Canonical correspondence analysis revealed that the availability of Quercus crispula mast, as well as seasonal factors, influenced use of the seven principal food categories by brown bears (dent corn, Q. crispula , Actinidia arguta , sika deer Cervus nippon , fish, Vitis coignetiae , and Sorbus commixta ). Higher berry availability was also associated with lower crop use by brown bears. Dent corn consumption persisted for longer periods during years with poor availability of Q. crispula mast, and bears continued to use the dent corn even after harvest. Dent corn use by brown bears decreased when the availability of natural food was high. Conversely, brown bears exploited crops at higher rates when crop availability was high. Our results suggest that the availability of both natural Q. crispula mast and dent corn determines the patterns of crop consumption by brown bears.