Group behaviour is widespread among animal taxa and can be driven by passive and/or active mechanisms. In the former, animals aggregate due to the presence of a common resource while in the latter, individuals intentionally seek out conspecifics or even favoured social associates. The heterogenous distribution of resources common across many ecosystems can make it difficult to tease apart the relative roles of passive and active mechanisms in the organization of animal groups. Given the heterogenous distribution of suitable roosts and a dependency on conspecifics for thermoregulation, both passive and active mechanisms may influence the organization of summer maternity groups of temperate bats such as the little brown myotis (Myotis lucifugus). In this study, we assess whether roost-use decisions are driven exclusively by fidelity to roosts, or if social preferences may also influence an individual’s decisions. To investigate this, we construct network models of roosting associations among bats in Salmonier Nature Park, Newfoundland, Canada. We construct null models that hold constant the proportion of times an individual uses a roost to approximate networks driven by only passive mechanisms. Evidence of network structure not explained by roost fidelity would suggest active mechanisms such as social preferences also impact individual roost-use decisions and thus the organization of bat maternity groups. As k-selected, long-lived animals, evidence of social complexity comparable to that of cetaceans, primates, and pachyderms would indicate intelligence as another characteristic of bats not expected by their small body size.