Nutritional condition and dietary profile of Japanese black bear (Ursus thibetanus japonicus) killed in western Japan in autumn 2004

Abstract

The nutritional conditions and dietary profiles of Japanese black bears that intruded into residential areas in Hiroshima, western Japan, in autumn 2004 were estimated. Nutritional conditions were evaluated using a morphometric index, the body-condition index (BCI) deduced for the American black bear, which has similar morphology and physiology to the Japanese black bear. The BCI had a wide range, from –3.0 to 3.5, indicating a wide range of nutritional conditions of the bears. There were no significant effects of age class, sex, or month of capture on the BCI. Dietary profiles were estimated by measuring the carbon and nitrogen stable isotope ratios (δ¹³C, δ¹⁵N) of bear hairs, which archive information on dietary changes during the growth of the hair. These values indicated wide-ranging diets that included C₃ plants, animal matter, and anthropogenic food, and identified marked individual differences in dietary profiles. Individuals with a high BCI tended to consume high-δ¹⁵N food such as animal matter and acorns. Because the proportion of individuals that acquired the high-δ¹⁵N food was small, the amount and distribution of such food items might have been restricted and subject to competition among bears in Hiroshima in autumn 2004.