Social dominance and cluster formation in Chaerephon pumilus (Molossidae)

The sequestering of resources by dominant individuals is commonly observed in group-living mammals. Most bats are gregarious, yet we do not know what impact social dominance may have on the way they share roosts, a common lim iting resource for many species. We videotaped a captive group of 10 little free-tailed bats (Chaerephon pumilus) to examine the relationship between social rank and ability to become part of clusters during roosting. Overall , bats of higher social rank were more successful in joining clusters. When the sexes were analyzed independently, males successfully joined clusters more often against lower ranked individuals, whereas females did not. Contr ary to predictions, the most dominant male did not exclude subordinate male s from joining clusters containing females. The nature of female relationsh ips is unclear, however they probably do not exert dominance over one anoth er while roosting because of the metabolic benefits of clustering.