Evaluation of sardine bait stations to monitor Asiatic black bear populations in Nagano Prefecture, central Japan

抄録

Regular monitoring of bear (Ursus spp.) populations is important to ensure that conservation policies are appropriate. Although population estimates may be less ambiguous than population trend estimates, they are more difficult and expensive to obtain. Bait station surveys are commonly used in North America to monitor bear population trends. We tested sardine bait stations as a monitoring tool for Asiatic black bear (U. thibetanus) populations in Nagano Prefecture, central Japan, in summer and fall 1999 and in spring 2000. We established 341 sardine bait stations in five study areas. Eighteen (X = 5.45%; range = 0-10.8%) bait stations were visited by bears and 21 (X = 6.36%; range = 0-17.8%) were visited by non-target animals, and 11 were discarded due to data collection concerns. In the only area we tested during three seasons (Northern Japanese Alps), we obtained the highest (8.3%) visitation rates in summer, the lowest (4.5%) in spring, and intermediate rates (5.6%) in fall. These visitation rates are too low to be a reliable indicator of bear abundance.