Social and vocal behavior in adult greater tube-nosed bats (Murina leucogaster)

Many studies have revealed the significant influence of the social nature and ecological niche of a species on the design and complexity of their communication sounds. The knowledge of communication sounds and particularly of the flexibility in their use among mammals, however, remains patchy. Being highly vocal and social, bats are well suited for investigating vocal plasticity as well as vocal diversity. Thus, the overall aim of this study was to test the presence of structural overlap between calls used in social communication and echolocation pulses emitted during foraging in greater tube-nosed bats (Murina leucogaster). Acoustic analysis and spectrotemporal decomposition of calls revealed a rich communication repertoire comprising 12 simple syllables and 5 composites with harmonics in the ultrasonic range. Simultaneous recording of vocal and social behavior in the same species yielded a strong correspondence between distinct behaviors and specific call types in support of Morton's motivation-structure hypothesis. Spectrographic analysis of call types also revealed the presence of modified components of echolocation pulses embedded within social calls. Altogether, the data suggest that bats can parse complex sounds into structurally simpler components that are recombined within behaviorally meaningful and multifunctional contexts.