Abstract
During the autumn and early winter of 2004, mass sightings of the Asiatic black bear, Ursus thibetanus, were recorded near human residences from northern to western Honshu. These mass sightings were caused by the failure of acorn crops, which serve as an important food source for bear over-wintering. We analyzed hairs from 95 bear individuals collected during a project implemented by the Environmental Ministry of Japan in 2004. Twenty of these specimens (two bears from Korea and 18 from Japan) were analyzed at successive 3-mm intervals, from the root to the tip of the hairs. Samples from Korea exhibited typical patterns of δ^<13>C and δ^<15>N: δ^<15>N values were high at the tip of hairs, increased in middle sections, and then decreased toward the root. These patterns were strongly associated with ecological observations that bears consume young leaves in the spring, catch insects during the summer, and then primarily consume acorns during the autumn. In contrast, patterns of δ^<13>C and δ^<15>N in Japan exhibited geographical variation: in some areas of western Japan, values of δ^<15>N rapidly increased at the root. The analysis of the hair roots of 95 bears indicated that individuals from the northern and central Alps, Northern Kinki, and western Chugoku had higher δ^<13>C values, suggesting a diet of C_4 foods, such as corns and related food residues. Some individuals from the Chugoku and Kii areas exhibited higher values of δ^<15>N. However, δ^<15>N values exhibited geographical variation; thus, sampling and δ^<13>C and δ^<15>N analyses of successive portions of bear hair are necessary for more thorough nutritional diagnoses.
