Audio-vocal feedback in bats and new roles for echolocation calls in social communication

An important aspect of auditory scene analysis is the specialized neurocircuitry required for vocal production. in a dynamic acoustic environment. Although often taken for granted, enhanced audio-vocal feedback is relatively uncommon in animals and yet an important precursor to vocal learning. We argue that vocal complexity in bats is an exaptation of the highly specialized audio-vocal feedback system that has evolved for echolocation. First, we explore how audio-vocal feedback enhances echolocation. Second, we review how echolocation pulses serve social functions by providing information to receivers (like gender, identity, or food availability). Third, using our research on molossid bats (family Molossidae), we explore whether vocal plasticity in sonar has contributed to an expanded role for sonar pulses in social communication. In at least three molossids, roosting bats rapidly sing in response to echolocation pulses of flying conspecifics. However, more importantly, we show that in multiple species, echolocation is produced in purely social contexts. Roosting bats embed pulses and feeding buzzes into their courtship songs that are not acoustically distinct than when foraging. Finally, some molossids not only sing in roosts, but also in flight—that is, they echolocate and sing simultaneously. These findings indicate that echolocation plays even more of a role in social communication than commonly believed and that the production of echolocation and social communication is tightly coupled and coordinated at a high level.