The anxious vole: the impact of group and gender on collective behavior under life-threat

Social animals behave collectively in order to maintain a cohesive group. This collective behavior is often led by a few individuals of specific gender, social rank, or spatial physical location in the group (i.e., perimeter or front). We examined how individual social voles (Microtus socialis) in same-gender compared with mixed-gender groups respond to an owl attack. We found that anxiety level, as measured by the time that each individual spent in less-sheltered sectors (open arms of elevated plus-maze and center of open arena), was affected by both the social context and the gender of the tested individuals. While both female and male voles generally reduced their activity in the open following owl attack, males in mixed-gender groups were exceptional in dichotomizing into those that spent a short period and those that spent a long period in the open arms of the plus-maze. Based on the similar responses of the same-gender groups, we suggest that anxiety is contagious, and based on the lower anxiety level of the mixed-gender groups, we suggest that natural groups that comprise both males and females are better able to cope with life-threat compared with same-gender groups. Finally, we suggest that the differential responses of males in the mixed-gender groups were due to a few males that displayed a low level of anxiety. These males were probably individuals of high social rank, and their response reflects their natural protective role, as previously described in social voles.