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Group coordination and the synchronization of activities are essential to maintain group cohesion during collective movements. Collective decisions arising from this synchronization are influenced by both ecological and sociodemographic factors. The spatial heterogeneity and temporal predictability of resources not only affect fission–fusion dynamics and patterns of movement, but also influence leadership processes. However, herd movements may also be affected by the propensity of certain individuals to initiate movements through individual characteristics such as sex and dominance. In this study, we examined how members of a European bison herd living in fission–fusion dynamics decide to move, and how they synchronize their nonforaging movements. Adult females appeared to initiate the majority of movements, while juveniles rarely did so. The number of followers for a collective movement was directly influenced by the sex and age of the initiator. Other factors also influenced the number of followers, such as the orientation and dispersion state of the herd. The initiator was more likely to be followed if it went in the direction indicated by the majority of individuals, suggesting a voting process. Subgroups of individuals joined movements using a mimetic process, confirming the fission–fusion dynamics of this species. The results of this study put a new slant on our understanding of the ecology and sociality of the European bison. In view of recent conservation studies suggesting that human–wildlife conflict could be avoided by controlling animal groups and particularly their leaders, our study could be an effective tool in the management of this species after reintroduction.

Coping styles represent alternative response patterns in reaction to a stressor. The coping style model provides a set of predictions about correlations between behavioural and neurophysiological reactions to a stressful situation. According to this model, high levels of activity should be correlated with high levels of aggressiveness at the behavioural level, and to high sympathetic reactivity, low parasympathetic reactivity (higher heart rate levels) and low hypothalamus–pituitary–adrenocortical (HPA) axis reactivity (low production of glucocorticoids in response to a stressor). More recent versions of the model, however, are challenging this view and consider the possibility of independent axes of coping style and stress reactivity. The coping style model has mainly been tested on artificially selected or inbred lines in laboratory settings. Such a situation restricts its generalization to a larger number of species and there is a need for studies testing it in the wild under more natural situations. Here, we test the predictions of the coping style model in a wild alpine marmot, Marmota marmota, population. We show that several behavioural (i.e. exploration in an open field, impulsivity and docility) and neurophysiological traits (i.e. heart rate, breathing rate and cortisol production) assumed to represent individual differences in coping style were significantly repeatable over 2–3 years. Not all the correlations between traits predicted by the coping style model were found in marmots, which supports the more recent two-axes model. Furthermore, most correlations were observed at the between-individual level, and the within-individual correlations (i.e. phenotypic plasticity) were weaker. Overall, our results support the prediction of the coping style model, but highlight the fact that the association between traits found in artificial conditions may be weaker in a more natural setting.