Do bats' social vocalizations conform to Zipf's law and the Menzerath-Altmann law?

The study of vocal communication in non-human animals can uncover the roots of human languages. Recent studies of language have focused on two linguistic laws: Zipf's law and the Menzerath-Altmann law. However, whether bats' social vocalizations follow these linguistic laws, especially Menzerath's law, has largely been unexplored. Here, we used Asian particolored bats, , to examine whether aggressive vocalizations conform to Zipf's and Menzerath's laws. Aggressive vocalizations of adhere to Zipf's law, with the most frequent syllables being the shortest in duration. There was a negative association between the syllable number within a call and the average syllable duration, in agreement with Menzerath's law. A decrease in the proportion of some long syllables and a decrease in the duration of several syllable types in long-duration calls explain the occurrence of this law. Our results indicate that a general compression principle organizes aspects of bat vocal communication systems.