Group size elicits specific physiological response in herbivores.

With increasing group size, individuals commonly spend less time standing head-up (scanning) and more time feeding. In small groups, a higher predation risk is likely to increase stress, which will be reflected by behavioural and endocrine responses. However, without any predator cues, we ask how the predation risk is actually processed by animals as group size decreases.

How group size affects vigilance dynamics and time allocation patterns: the key role of imitation and tempo.

In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation ('group size effect'). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior.

Personality and collective decision-making in foraging herbivores.

The mechanisms by which group-living animals collectively exploit resources, and the role of individuals in group decisions, are central issues for understanding animal distribution patterns. We investigated the extent to which boldness and shyness affect the distribution of social herbivores across vegetation patches, using sheep as a model species. Using an experimental and a theoretical approach, we show that collective choices emerge through the nonlinear dynamics of interactions between individuals, at both short and long distances.

Moving together: Incidental leaders and naïve followers.

Elucidating whether common general mechanisms govern collective movements in a wide range of species is a central issue in the study of social behaviour. In this paper, we describe a new experimental paradigm for studying the dynamic of collective movements. Some sheep (Ovis aries) were first trained to move towards a coloured panel, in response to a sound cue.

Sexual dimorphism, activity budget and synchrony in groups of sheep.

The activity budget hypothesis has been proposed to explain the social segregation commonly observed in ungulate populations. This hypothesis suggests that differences in body size--i.e.

An experimental study of social attraction and spacing between the sexes in sheep.

Most ungulates are gregarious species and outside the mating season are typically observed in single-sex groups. However little is known about the mechanisms underlying social segregation between sexes. We investigated the effect of conspecific attraction on individual spacing between unrestrained merino sheep Ovis aries and confined conspecifics.