Social vocalizations indicate behavioural type in bats.

Vocalizations play a crucial role in the social systems of many animals and may inadvertently reveal behavioural characteristics of the sender. Bats, the second largest mammalian order, rely extensively on vocalizations owing to their nocturnal lifestyle and complex social systems, making them ideal for studying links between vocalizations and consistent behavioural traits. In this study, we developed a new testing regime to investigate whether consistent individual vocalization differences in nectarivorous bats are associated with specific behavioural types. We exposed 60 wild, male bats to novel and risky stressors and assessed their behavioural and vocal responses. Proactive, exploratory and bold bats were more likely to produce social calls, and among the vocalizing bats, more agitated bats produced higher numbers of social calls. We thus show that bat vocalization behaviour can be indicative of a certain behavioural type, potentially allowing conspecifics to assess personalities from a distance, which in turn could impact subsequent social interactions, group dynamics and reproductive success. Our results, in combination with previous findings in birds, suggest that advertent or inadvertent long-distance broadcasting of personality may be widespread, thus opening up new exciting questions about the links between vocalizations and sociality.