Social structure, emergence behaviour and roost switching in female little brown bats (Myotis lucifugus)

Abstract

The evolution of sociality involves trade-offs between benefits (e.g. protection from predation, information transfer) and costs (e.g. transfer of disease, competition). This study investigated the potentially social behaviour of little brown bats (Myotis lucifugus) at two maternity colonies in Newfoundland using passively integrated transponders. Emergence order on the busiest days of the season was examined at different roosts for patterns in the order in which bats emerged . Emergence order was significantly concordant, but bats formed only weak associations that lasted 30-80 days, based on proximity in emergence time. There was variation in day roost use by bats, with the number of switches in day roosts ranging from 0 to 37 per season. Night visits to roosts were greater for reproductive bats, especially during the lactation period. I hypothesized that bats that visited more roosts during the night would be more social, but there was no support for this, and there was no observed difference in social measures between reproductive classes. These finding suggest that female little brown bats maintain weak associations throughout a season, and reproductive status influences their night behaviour, specifically roost visitation frequency.