Bats are altricial, gregarious, and highly vocal animals. As such, they are compelling animal models for bioacoustic analyses of language-related traits. Insight into the vocal development of bats can provide a more comprehensive understanding of animal communication. We report the phenomenon of syllable merging in Hipposideros larvatus by analyzing changes to their isolation calls during ontogeny. Our findings indicate that composites in adult social calls originate from isolation calls. As pups developed, the interval between simple syllables gradually shortened, and different types of simple syllables combined into composites that were used for social communication. To our knowledge, this is the first study to report this phenomenon in constant frequency-frequency modulated (CF-FM) bats, and it might be a unique feature of isolation call development in H. larvatus.
Bats, isolation calls, syllable merging, vocal ontogeny