Tottori University of Environmental Studies, Japan
Abstract: Many reports on wildlife-vehicle collisions (WVC) in Japan indicate that the period of wildlife home range expansion coincides with the period of high WVC. However, since many of these reports are records prepared by road managers, the lack of information on the characteristics of the animals affected as well as the low accuracy of identification is problematic. This study aims to obtain accurate information by directly measuring the carcasses resulting from WVC and to examine possible hypotheses on the causes of roadkill based on previous studies on roadkill using the information from the measured carcasses. Based on previous studies, ecological characteristics such as breeding season and behavior patterns are considered to be factors in the occurrence of WVC, since the period of increase in WVC coincides with the period of expansion of the activity zone, such as the breeding and dispersal seasons. We hypothesized that if these ecological characteristics were factors in the occurrence of WVC, WVC would have a variation in the number of roadkill due to differences in the action zone and life history of the sexes. To verify our hypothesis, we directly observed 390 animal carcasses collected during road maintenance operations on roads in eastern Tottori Prefecture between May 17, 2021 and October 28, 2022, to confirm sex and size ratios. The following results were obtained. (1) For Japanese badgers (Meles anakuma), the number of WVC involving male badgers exceeded that of females from May to July, during the dispersal season of sub-adults and during the estrous season, when male adults are at their maximum activity range. The number of WVC decreased during the season of hibernation (from November to March). (2) For Japanese raccoon dog (Nyctereutes procyonides viverrinus), the number of WVC of both sub-adults and adults increased during the period of independence of sub-adults and the period when adults expand their activity range for feeding in preparation for winter. (3) For Japanese marten (Martes melampus melampus), the number of WVC was higher for males, which have a larger home range of activity, than for females throughout the year. These results support the hypothesis that species ecological and life history characteristics are a factor in the occurrence of WVC.
