The role of vocalizations in agonistic interactions during competition for roosts in a solitary bat

Inter- and intraspecific competition for resources is common among individuals which share ecological niches. To avoid physical confrontations, individuals can use various types of signals to demonstrate their dominance, including vocalizations. Kerivoula hardwickii is a solitary bat species that lives in highly ephemeral plant structures, which are therefore a limited resource. So far, it is unknown if individuals of K. hardwickii use vocalizations during competitive encounters for roosts, and if the intention of these vocalizations can be deduced by potential rivals. We hypothesized that the calls emitted during roost competition contain information that influences the ability of an individual to defend its roost. We conducted roost competition experiments in a flight cage, where there was an individual roost owner and an intruder who would attempt to evict the owner from the roost. All the vocalizations emitted during these encounters were recorded and analyzed to determine which acoustic parameters, if any, had an influence on the successful defense of the roost. We found that the calls emitted by males can influence their ability to defend the roost, and that entropy is the parameter that most strongly explains a successful defense. High entropy suggests that encounters between individuals of K. hardwickii escalate to high levels of aggressiveness and explain whether calls influence an individuals capacity to defend a roost. We suggest that bat vocalizations contain important information about individual characteristics, which in turn help bats make decisions during resource competition.