North-South variations in sika deer ecology as a forest-dwelling cervid

Abstract

Sika deer on the Japanese Archipelago inhabit a variety of habitats with different climatic conditions. I review the significance of this north-south variation for the ecology of sika deer. Because of warm and humid summers, plant growth is vigorous in Japan, resulting in a prevalence of forests. The keen hearing and agility of sika deer and their dependence on forest plants as foods suggest that the sika deer is a cervid adapted to forest environments. The northern deciduous forests are characterized by marked seasonal changes in temperature and consequent plant growth. They are densely covered with Sasa species (dwarf bamboos). The abundant Sasa species are evergreen and are particularly important foods for overwintering sika deer. Snow hinders deer locomotion and reduces food availability. Seasonal events such as rut and parturition are synchronized within short periods. Larger body size and greater fat deposits are advantageous to overwintering. The sika deer show seasonal elevational movements depending on snow. In contrast, southern evergreen forests are often dark, and shrubs and forbs in the understories are less abundant and often unpalatable. The southern sika deer are browsers and eat fruits and seeds in autumn and winter. They are sedentary and live in small groups. The sika deer demonstrates how an ungulate can change its ecology in different environmental conditions.