EN
Seasonal changes in the population size and habitat use of sika deer Cervus nippoti Temminek. 183S in the high Tanzawa Mountains were studied. Deer exhibited seasonal movements different than those usually observed in the mountains. Because dwarf bamboo, their main winter food, recently occurs only in the high Tanzawa Mts, deer concentrated at the high altitude in late autumn and moved down in winter, after the reduction of bamboo biomass. The most utilized habitat types were forest clearings due to the highest food biomass available. Closed woodland was selected mostly in autumn and winter when deer often fed on fallen leaves and tree bark. Open woodland without bamboo in the understory was highly avoided. Sika deer population in the Tanzawa Mts should be kept at the stable level, which would enable recovery of vegetation. Because recent shrinking in bamboo distribution occurs mostly due to deer grazing pressure in winter, it was suggested to manage habitats in the low mountains in the way to make them attractive to deer also during winter. Supplemental feeding in the low mountains should be also considered.