Roost fidelity partially explains maternity roosting association patterns in Myotis lucifugus

Abstract

Resources that draw individuals to a specific location may result in the formation of groups and development of individual social preferences. Simultaneously considering both ecological and social factors can therefore reveal underlying mechanisms of group formation and organization. Females of some temperate bat species roost in groups during the spring and summer months within which they give birth to and nurse their pups. Females switch roosts frequently, but the factors that influence roost switching remain poorly understood. To characterize the structure of a bat maternity group and gather evidence for the role of social preference in shaping this structure, we used roost co-occurrence data from little brown myotis, Myotis lucifugus , implanted with passive integrated transponder tags and roost boxes monitored with passive readers in Salmonier Nature Park, Newfoundland, Canada. By developing informed null models, we more directly investigate hypotheses that may explain why bats roost together. Although our results suggest that association patterns of maternity groups can largely be explained by similar interindividual patterns in bats' roosting frequencies within a given roost box (roost fidelity), other factors are likely to contribute to the observed structure. We thus provide support for the potential influence of roost and social preferences in shaping maternity group structure. • Female bats frequently switch roosts, changing who they roost with each day. • Some bats did not roost together at frequencies expected by chance. • Other bats occasionally roosted together more than expected by chance. • Social preferences may be important in influencing roosting decisions.