Temporal Responses to Warming: Do Wild Herbivores Trade Off Heat, Predators, and Humans?

Area of Science:

• Ecology and behavioral science
• Wildlife conservation and management
• Climate change impacts on animal behavior

Background:

• Environmental changes, including warming and human disturbance, alter mammal activity patterns.
• Increased nocturnality may occur despite predator risks to cope with thermal stress.
• Understanding the combined effects of multiple stressors is crucial for predicting population consequences.

Purpose of the Study:

• To investigate the influence of ambient temperature, predators, and human presence on deer activity.
• To assess temporal responses, including daily activity levels and nocturnality, in roe deer and fallow deer.
• To disentangle the relative roles of different environmental stressors on wildlife behavior.

Main Methods:

• Intensive camera trapping across Mediterranean protected areas (∼12,400 trapping days; 196 sites).
• Evaluation of daily activity patterns and nocturnality in roe deer (Capreolus capreolus) and fallow deer (Dama dama).
• Statistical analysis of environmental factors (temperature, predator visitation, human presence) on temporal activity.

Main Results:

• Both deer species reduced daily activity with warmer temperatures, likely for thermoregulation.
• Roe deer exhibited increased nocturnality with warming, while fallow deer showed only a weak response to wolf presence.
• Human visitation rate did not significantly affect activity levels or nocturnality in these protected areas.

Conclusions:

• Species-specific behavioral adjustments to environmental change are evident, with varying responses to heat and predation.
• Fallow deer may balance heat avoidance with predator avoidance, while roe deer prioritize thermoregulation.
• Anticipated climate warming may lead to differential population viability consequences for these herbivore species.