Abstract
Careful management is necessary for two bear species, the brown bear (Ursus arctos) and the Asiatic black bear (U. thibetanus), as game animals in Japan. We reviewed the population size estimations and population trends of these bears for their management planning and implementation. Several methods, such as questionnaires on status, harvest statistics, demographic indicator analysis, direct count, capture-mark-recapture, camera trap, field sign and hair trapping, have been applied for estimating population sizes of the bears. The bear harvest can be more influenced by environmental fluctuations such as mast production and management policies than actual population fluctuation. Snow cover and other field conditions may influence the direct count method. The field sign method can be used for population trend studies, but not for absolute population estimation. Six prefectural governments of 17 which have made bear management plans for specific wildlife management system have applied the hair trap method, which has been developed in recent years, for the census of the Asiatic black bears. The entire estimated population of the Asiatic black bear based on local government reports was 13,169 to 20,864, including the process of extrapolation to the entire range in Japan. A study on the reliability of estimated population size methods is requested through further monitoring of the bears by central and local governments.
