Individual gregariousness predicts behavioural synchronization in a foraging herbivore, the sheep (Ovis aries).

Diversity of animal personalities has been proposed to arise from differences in social attraction, and to enhance behavioural flexibility of a population. The present study evaluated gregariousness as a personality trait in 14 ewes kept on pasture. Gregariousness was defined based on the frequency of having a close neighbour (<3m). Highly gregarious (HG) and less gregarious (LG) animals were separated into two groups (n=7) which were reintegrated after 18 days. During direct field observations, behaviour was recorded individually every 15 min. Each session lasted 2.5h (08.30-11.00 h or 14.30-17.00 h, respectively). Behavioural synchronization was highest when the group consisted only of HG individuals (κHG=0.69, κLG=0.31; t=5.29; p<0.001), indicating that gregariousness predicted behavioural synchronization in sheep. Though sheep are generally recognized as a highly gregarious species, HG and LG individuals could be differentiated clearly and consistently. Research on animal personality might help explain social influences on behavioural synchronization.