Abstract
In Okinawa-jima Island, we have monitored the population trend of Orii's flying fox Pteropus dasymallus inopinatus for a long time since 2000, and we found a tendency of increasing of observed number of bats. We monthly counted foraging bats in two sites (urban and forested area) using road census methods from September 2001 to August 2009 and from April to March 2004 and 2008, respectively. Threefold increase was found in both areas during 8 and 4 years, and it was found in every season. These results suggest that the bat's population in Okinawa-jima Island is growing, not a spatial heterogeneity in bat's habitat use. The raise of annual growth rate coincided with the decreasing number of typhoons. It seems that the bat population size depends on the frequency of disturbance of typhoons. We should take account of the spreading of agricultural damages and the extinction of this subspecies resulting from unstable fluctuation of populations under the global warming.
