Forest road use by medium-sized mammals in winter snow environments in a hilly area

Forest roads are networks for forest management and operations closely associated with mammal habitats. Some mammals often select forest roads for movement and foraging; however, the use during winter with snow cover is unknown. This study clarified forest road use by medium-sized mammals in winter snow environments in a hilly area. We set camera traps on forest roads and interior forest sites during winter in a snowy region of northeastern Japan in 2021 and 2022. We calculated the road-use index of four medium-sized mammals, and analyzed relationships between the occurrence frequency and snow conditions and slope angle in each species. Red foxes ( Vulpes vulpes Linnaeus, 1758) and raccoon dogs ( Nyctereutes procyonoides (Gray, 1834)) significantly occurred at the gentle slope sites regardless of year, and these species walked along the forest road. Japanese martens ( Martes melampus (Wagner, 1840)) tended to walk along forest roads with a gentle slope only in 2022. Although Japanese hares ( Lepus brachyurus Temminck, 1844) significantly occurred at the gentle slope sites, they showed no tendency to walk along forest roads. No significant differences were detected in sinking depth in the analyses of each species. Our results show that forest roads with a gentle slope, a low movement cost, created by modifying landforms can alter the behavior of some mammals, even in snowy environments.