Who are the bosses? Group influence on the behavior of voles following owl attack

• Social status in voles is reflected in body mass (greater mass = higher social rank).
• After owl attack, voles display the mid-level activity of the high-ranking members.
• Many low-mass voles seem to follow the behavior of the high-mass voles.
• High-mass voles lead and stabilize the group, reducing its divergence under threat.
• Behavior may propagate faster in hierarchical compared to non-hierarchical groups.

Individual members of a group must conform to the group norms, as they may otherwise become isolated from the group or the group may split. On the other hand, social groups usually comprise various social ranks and display a differential division of labor and consequently different behaviors. The present study was aimed at examining how the above factors are manifested in social voles that had experienced owl attack. Here, we reconfirm the findings of past studies: that grouped voles converge to display similar behavior after owl attack. In addition, we found that high-mass voles were more active in the open sectors of the experimental set-ups both before and after the owl attack, whereas low-mass voles dichotomized to those that increased and those that decreased their activity in the open following owl attack. Taking body mass as a proxy for social rank, it is suggested that as a consequence of their larger size and of their experience and physical strength, high-mass voles both presented an exemplary model for the low-mass voles and, accordingly, assumed leadership and stabilized their group's behavior. We also suggest a hypothetical model for the propagation of behavior in hierarchical groups.