The Importance of Individual Body Condition in Mammalian Behavioural Responses to Disturbance

ABSTRACT Introduction Behavioural responses are widely used to assess disturbance impacts on mammals, yet body condition has received less attention. Energy state influences how mammals balance foraging against safety, making body condition—a reflection of energy reserves—a critical but overlooked factor in disturbance responses. We propose that mammals follow predictable, state‐dependent strategies when responding to disturbance. Methods We reviewed theoretical frameworks for how body condition shapes behavioural responses to danger. Then, we examine how energetic demands vary by life‐history, draw on predator–prey studies showing body condition influences risk acceptance, and finally, review the limited studies directly examining body condition effects on disturbance responses. Results We identified three theoretical frameworks—asset‐protection, needs‐based, and ability‐based strategies—that predict how body condition influences behavioural responses to disturbance. Energy demands differ by sex, age, reproductive status, and life‐history strategy, creating variation in how individuals balance foraging needs and safety when energetically challenged. Predator–prey studies reveal a consistent pattern: poor‐condition individuals adopt needs‐based strategies (increased foraging, reduced vigilance) while good‐condition individuals follow asset‐protection strategies (heightened vigilance, greater reactivity). Although fewer studies examine body condition in anthropogenic disturbance contexts, they show the same relationship, suggesting these principles extend to human‐wildlife interactions. Discussion As climate change intensifies nutritional stress, understanding body condition's role in disturbance responses becomes increasingly critical. More individuals may exhibit reduced responses not from habituation, a common management assumption, but from heightened foraging needs. Behavioural studies must incorporate body condition to avoid misinterpreting impacts and develop effective management strategies.