Perception of social vocalizations in bats

Abstract

Although bats are well known for their highly specialized echolocation systems, the majority of produce social vocalizations whose form, function, and complexity vary widely across taxa. Here we review and compare two types of social vocalizations bats produce and perceive: infant isolation calls and complex songs. Infant isolation calls are simple (2 notes), innate vocalizations produced by the majority of mammals with little specialization in bats. Research has shown that auditory sensitivity co-evolved with isolation call frequencies across bats and bats can discriminate among individuals using isolation calls. In contrast to isolation calls, Tadarida brasiliensis songs are much more complex (100’s of notes), hierarchically structured and highly variable across renditions. Playbacks revealed that bats rapidly perceive echolocation from passing conspecifics and sing in response. This occurs only in response to echolocation, even though “echolocation” calls are embedded within complex song phrases. Thus, bats can rapidly discriminate between “echolocation alone” and “song with echolocation embedded” signals. We further share some evidence of differences in the syntax of songs produced in response to songs from familiar and unfamiliar bats. These studies and new discoveries of bats’ songs will no doubt have a large impact on our understanding of vocal perception and cognition.