Balancing risk: the influence of human disturbance and predators on roe deer activity patterns

Animal activity patterns are influenced by endogenous and exogenous factors, with human disturbance and predator presence playing a key role in fearful prey. This study explored diel activity patterns of the roe deer (Capreolus capreolus) across different study areas with varying levels of human disturbance and predator presence, specifically wolves (Canis lupus), located in northwestern Italy. We conducted seasonal camera-trapping sampling sessions for 2 years (2020-2022); we deployed 502 camera traps for a cumulative sampling period of 6,709.5 trapping days, and we collected 2,749 roe deer events. Roe deer exhibited generally bimodal diel activity patterns with peaks at dawn and dusk across all study areas, reflecting their crepuscular behavior. The consistency of the patterns can be attributed to biological constraints, such as mating and foraging needs, as observed during spring across all study areas, or to the absence of variations in perceived risks, as observed where human disturbance remains constant throughout the year. Interestingly, significant local and seasonal variations were also observed. Nocturnal activity varied seasonally and was influenced by landscape composition and predator presence, with lower nocturnal activity in modified landscapes during summer and autumn, likely due to favorable daytime conditions, and lower nocturnal activity in areas with stable wolf presence, particularly in winter, suggesting an antipredator response. Our results indicated that roe deer adapt their activity patterns to mitigate risks, demonstrating behavioral plasticity in response to the environment. This behavioral adaptability may be a key trait that facilitates the expansion of the species into highly anthropized landscapes, allowing roe deer to thrive in increasingly urbanized environments.