Vigilance levels of sika deer in nonhunting areas with moderate human activity

During predator–prey coexistence, prey species have developed anti-predator behavior to reduce predation risk. In terrestrial ecosystems, humans are the major predators of wild cervids (Cervidae, Cetartiodactyla, Mammalia) in regions where large carnivores have gone extinct due to anthropogenic persecution. Typical anti-predator behavior exhibited by wild cervids includes increasing nocturnality and vigilance. We investigated diel activity and vigilance in sika deer (Cervus nippon) in nonhunting areas using camera-trapping techniques, to determine whether human visitation (i.e., nonlethal effects) increases their nocturnality and vigilance. We established two study sites––inside (low risk) and outside (high risk) of a wildlife reserve at University of Tokyo Chichibu Forest, Saitama, Japan. We hypothesized that in sika deer, nocturnality and vigilance would increase at high-risk site (outside of the reserve), due to the high rate of human visitation. However, vigilance level and diel activity between the two study sites were not different. In female deer, vigilance increased in winter regardless of the site studied. Our findings suggest that hunting activities (e.g., drive hunting with dogs) outside of the studied areas triggered anti-predator behaviors, such as increased vigilance, in sika deer, although our studied sites were not designated as hunting area. Further studies need to elucidate what types of human activities and intensity levels trigger anti-predator behaviors by wild ungulates.