Temperament and state-dependent behaviours in large herbivores

Behavioural consistency and plasticity can both benefit fitness. Repeatability in behaviour within a specific context, termed temperament or trait-like behavioural responses, fosters adaptive responses to stimuli. Behavioural plasticity, on the other hand, enables state-like responses, aligning behaviour with internal and external conditions. The nutritional state of an organism significantly impacts behaviours and may interact with temperament. However, the specific contributions of trait- and state-like responses to stimuli remain poorly understood. Using a long-term data set on mule deer, Odocoileus hemionus , elk, Cervus canadensis , and bighorn sheep, Ovis canadensis , we assessed the interplay of temperament and nutritional state in behavioural responses during handling. We measured the repeatability of kick rates across multiple capture events over time, investigating its association with temperament, nutritional condition, age and capture frequency. Bighorn sheep and mule deer exhibited high repeatability in kicks during capture, while elk did not. State-dependent factors, such as body fat, minimally influenced kick rates during capture. In bighorn sheep and mule deer, trait-like responses were likely related to temperament, whereas elk demonstrated neither state- nor trait-like behavioural responses. Trait-like responses in these species may reflect adaptations to specific ecological niches and site-specific evolutionary pressures. Our findings advance our understanding of these mechanisms, shedding light on the complex interplay between temperament, nutritional state and behaviour. Nevertheless, our results highlight the need for caution when predicting or extrapolating behavioural responses to stressors across closely related species. • We assessed behavioural responses of mule deer, elk and bighorn sheep during capture. • We measured behavioural repeatability in relation to temperament, condition and age. • Bighorn sheep and mule deer showed high repeatability in behaviour but elk did not. • Responses may reflect niche adaptation and site-specific selection pressure. • Caution should be used when predicting closely related species' stress responses.