Influence of the density of a sika deer population on activity, habitat use, and group size

The influence of population density of sika deer (Cervus nippon) on their a ctivity, habitat use, and habitat-related group size was studied in the are a of Japan's Tanzawa Mountains in early winter. The percentage of active si ka deer was higher in January 1994 (a low-density period) than in January 1 995 (a high-density period). The pattern of habitat use differed between pe riods. During the high-density period, deer increased their relative use of lower quality habitats. A possible mechanism and implications of this are discussed. Changes in population density had a positive effect on group siz e in sika deer, though the variation among habitat types supported the hypo thesis that food biomass is an important determinant of group size.