We addressed decision‐making processes in the collective movements of two groups of Przewalski horses (Equus ferus przewalskii) living in a semi free‐ranging population. We investigated whether different patterns of group movement are related to certain ecological contexts (habitat use and group activity) and analysed the possible decision‐making processes involved. We found two distinct patterns; ‘single‐bout’ and ‘multiple‐bout’ movements occurred in both study groups. The movements were defined by the occurrence of collective stops between bouts and differed by their duration, distance covered and ecological context. For both movements, we found that a preliminary period involving several horses occurred before departure. In single‐bout movements, all group members rapidly joined the first moving horse, independently of the preliminary period. In multiple‐bout movements, however, the joining process was longer; in particular when the number of decision‐makers and their pre‐departure behaviour before departure increased. Multiple‐bout movements were more often used by horses to switch habitats and activities. This observation demonstrates that the horses need more time to resolve motivational conflicts before these departures. We conclude that decision‐making in Przewalski horses is based on a shared consensus process driven by ecological determinants.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms 1 Exploring aggression regulation in managed groups of horses Equus caballusAbstract. Horses are highly social animals that have evolved to live in social groups.However, in modern husbandry systems, single housing prevails where horses experience social isolation, a challenge-to-welfare factor. One major reason for this single housing is the owners' concerns that horses may injure each other during aggressive encounters. However, in natural conditions, serious injuries due to aggressive encounters are rare. What could therefore explain the claimed risks of group living for domestic horses? Basing our questioning on the current knowledge of the social life of horses in natural conditions, we review different practices that may lead to higher levels of aggression in horses and propose practical solutions.Observations of natural and feral horses mostly indicate a predominance of low frequencies and mild forms of aggression, based on subtle communication signals and ritualized displays and made possible by group stability (i.e. stable composition), dominance hierarchy and learning of appropriate social skills by young horses. Obviously, adults play a major role here in canalizing undesirable behaviours, and social experience during development, associated with a diversity of social partners, seems to be a prerequisite for the young horse to become socially skilled.Given the natural propensity of horses to have a regulation of aggression in groups, the tendency to display more aggression in groups of domestic horses under some management practices seems clearly related to the conditions offered. We therefore review the managing practices that could trigger aggressiveness in horses. Non social practices (space, resource availability) and social practices (group size, stability of membership, composition and opportunities for social experiences during development) in groups of domestic horses are discussed here.2 Finally, we propose simple practical solutions leading to more peaceful interactions in groups of domestic horses, based on the knowledge of horses' natural social life which therefore should be enhanced (e.g. ensuring roughage availability, favouring group stability,, introducing socially experienced adults in groups of young horses;…). The state of the art indicates that many questions still need to be answered. Given the importance of the associated welfare issues and the consequences on the use of horses, further research is required, which could benefit horses… and humans.

International audienceAlthough nonhuman primates' gestural communication is often considered to be a likely precursor of human language, the intentional properties in this communicative system have not yet been entirely elucidated. In particular, little is known about the intentional nature of monkeys' gestural signalling and related social understanding. We investigated whether olive baboons can (1) adjust their requesting gestures to the visual attention of the experimenter with special emphasis on the state of the eyes (open versus closed), and (2) flexibly tailor visual and auditory-based gestures to elaborate their communication as a function of whether or not the experimenter can see them. Using a food-requesting paradigm, we found monkeys able to favour either visual or auditory-based requesting gestures to match the experimenter's visual attention. Crucially, when the human was not visually attending, they silenced visual gestures to some extent but performed more attention-getting gestures. This is, to our knowledge, the first report of monkeys elaborating attention-getting signals to compensate for communication breakdown. Gestural communication was also supported by gaze alternation between the experimenter's face and the food, especially when the human was visually attending. These findings offer evidence that olive baboons understand the state of the eyes in others' visual attention and use requesting gestures intentionally. They emphasize that Old World monkeys shift to acoustic communication when the recipient is not visually attending. In contrast to that of human infants and great apes, this acoustic communication is purely gestural, not vocal