Den site selection and utilization by the red fox in Hokkaido, Japan

Den site selection and den use by the red fox, Vulpes vulpes, were studied on the Nemuro Peninsula, eastern Hokkaido, Japan. Certain physical variables of 144 fox den sites were compared with those of 236 randomly selected control locations. The red foxes on the Nemuro Peninsula clearly preferred to den on slopes in woodlands near open spaces and streams. The seasonal pattern of den utilization was studied from June 1986 to May 1987. Red foxes used dens mainly during the period from January to June. Since this period coincides with the gestation, parturition and cub rearing periods of the red fox, it was confirmed that the red fox's den was fundamentally a breeding site. Almost all dens were observed each spring from 1986 to 1996 to establish whether they were used for breeding or not, and it was found that the number of fox families was stable during this decade.