Doing what your neighbour does: neighbour proximity, familiarity and postural alignment increase behavioural mimicry

Nonconscious behavioural mimicry, acting similarly to one's social partner, is thought to be a core component of group cohesion and coordination. However, the mechanisms contributing to this phenomenon are poorly understood. Understanding why behaviour is mimicked in some contexts but not in others is an important step in developing hypotheses about how and why some behaviours spread between social partners. Here we examine mimicry of routine vigilance during grazing episodes in a population of free-ranging bighorn sheep, Ovis canadensis, rams. Results indicate that vigilance bouts are more likely to be mimicked when neighbouring rams are in closer proximity, more familiar with one another and posturally aligned. Additionally, older rams are more likely than young rams to mimic the vigilance bouts of others, and mimicry occurs more often when the initiating ram is lower ranking than the mimicking ram. We interpret these findings within the framework of biases in attentiveness to particular individuals as a possible mechanism leading to the occurrence of behavioural mimicry.