Factors Affecting Pre-Denning Activity in Asian Black Bears

Hibernation (denning) is an important aspect of the life history of Asian black bears (Ursus thibetanus), and denning chronology can be influenced by biotic and abiotic factors. We investigated activity patterns during the pre-denning period of Asian black bears using statistical process control in combination with activity sensors to quantitatively identify a marked reduction in activity from 2006 to 2017 in the Ashio–Nikko Mountains, Japan. Pre-denning activities were detected in 29 of 35 cases (83%), with an average duration of 2.7 ± 1.7 days, which is one to three days shorter than the duration for brown bears (U. arctos). The effect of bear's age, sex, and the abundance of hard mast on the duration of pre-denning were not significant.