動物学：エジプトルーセットオオコウモリの鳴き声に含まれる多彩な情報

Vocalizations by Egyptian fruit bats contain information about who the call is addressed to, according to a study published in Scientific Reports this week. In an analysis of almost 15,000 vocalizations, the authors found that the calls contain information including the identity of the caller as well as its context.

Bats are social mammals that often roost in large colonies, and commonly engage in social interactions. They rely heavily on vocalizations for social communication, yet little is known about the function and informational content of these calls.

Yossi Yovel and colleagues recorded the vocalizations of 22 Egyptian fruit bats over the course of 75 days. From this, the authors assembled a dataset of approximately 15,000 vocalizations, which represented the full vocal repertoire the bats used during the experiment. By analysing this dataset, the authors suggest that the vocalizations contained information about the identity of the emitter and of the bat being addressed by the call. While most of this species’ vocalizations are emitted during aggressive encounters, by analysing the spectral composition of the calls, the authors were able to distinguish their specific aggressive context (such as squabbling over food, sleeping spots or other resources). Although animal calls are often grouped into one category in acoustic studies due to the difficulty of cataloguing them, the authors suggest that delving into these calls could be beneficial.