Does sociality increase survivorship in bats

Abstract

Bats are highly gregarious mammals, and many species within the taxa exhibit social behaviour. Several hypotheses on the costs and benefits of sociality amongst bats have been investigated, including social thermoregulation, predator avoidance, and pathogen transfer. From other taxa, we know that the probability of survival may vary with an individual’s gregariousness. Thus, we examined if individual sociality explains the individual’s probability of annual survival in female little brown myotis (Myotis lucifugus). By implanting bats with passive integrated transponders and monitoring several roost boxes with readers, we monitored co-roosting frequency among little brown myotis in a maternity group. We employed social network analysis to quantify sociality with the network metrics strength and betweenness centrality. We found that adult female bats with a higher strength and thus more associates had a lower probability of survival to the next year. However, we found no significant change in the probability of survival based on their betweenness centrality, or how influential the individuals were in linking different subgroups together. There was no evidence that sociality amongst juveniles had a significant effect on the probability of survival. This suggests that there might be other drivers of sociality, such as roost limitation or fitness benefit of maternal sociality on juvenile survivorship. With white-nose syndrome drastically changing group sizes among North American bats, research into understanding the potential impacts of sociality on survivorship is of significant conservation importance.