Demographic Parameters of Asian Black Bears in Central Japan

Currently, fundamental demographic data for wild Asian black bears (Ursus thibetanus) in Japan are lacking. As a first step toward science-based management, we must improve our understanding of life history characteristics such as reproduction and mortality. This study aimed to quantify the demographic parameters of Asian black bears in central Japan. (1) By measuring the cementum annuli width of the teeth of females, age at first reproduction was estimated to be 5.44 ± 0.22 (mean ± SE) years and reproductive interval 2.38 ± 0.48 years. (2) By counting placental scars in uteri sampled from recovered bear carcasses, we estimated litter size to be 1.58 ± 0.09 cubs and minimum age at primiparity to be two years. (3) We clarified the annual rates of natural mortality (0.108, 95% CI: 0.064–0.174) and human-caused mortality (0.005, 95% CI: 0.002–0.021) by using capture–recapture records for subadult and adult bears. We used observation data from the first six months after birth to estimate cub mortality rate (0.235, 95% CI: 0.080–0.465). Further research will allow us to identify which endogenous and exogenous factors affect demographic parameters and to use these parameters to estimate population dynamics as a next step.