Acoustic Repertoire of the Philippine Tarsier (<i>Tarsius syrichta fraterculus</i>) and Individual Variation of Long-Distance Calls

Abstract

We present the spectrographic description of the vocal repertoire of the Philippine tarsier ( Tarsius syrichta fraterculus ), a solitary living nocturnal primate for which a very limited information about acoustic communication exists to date. The majority of vocalizations were performed around sunset and, less frequently, at sunrise. We identified eight call types. Five calls recorded during communication between adults included three long-distance calls—loud call, smack-whistle, and whistle—then a soft locust-like chirp and a bird-like trill. Two other calls—cheep and twitter—were recorded during mother-infant communication. One distress call was emitted by adults during handling. All calls were performed in the 9752 Hz to more than 22 kHz frequency range. This study provides the first evidence of individual variation in the long-distance calls performed by tarsiers. Moreover, our study provides a basis for future comparison within as well as between tarsier species taxonomy. Bioacoustic methods can be used in monitoring of these cryptic species and determining their distribution range. Thus, bioacoustic studies can help to improve conservation strategies of different population/species.