The Vocal Repertoire of the Northern Giant Mouse Lemur (Mirza zaza) in Captivity

Abstract

Detailed knowledge of a species’ vocal repertoire is an essential component for the interpretation of its social interactions and behavior. In the case of cryptic nocturnal primates, vocalizations are also a valuable tool for species identification, and possibly to discriminate between the sexes and/or group memberships during noninvasive field identification, monitoring, and conservation efforts. Here we describe the vocal repertoire of the northern giant mouse lemur, Mirza zaza, a small nocturnal primate endemic to northwest Madagascar, and analyze the repertoire to identify vocalizations for field identification and monitoring. We recorded vocalizations of a captive population of 40 M. zaza individuals at the Duke Lemur Center, USA, with detailed observations of call-associated behaviors of eight individuals in two groups. Based on their acoustic structure, we identified 10 different call types, which were correctly classified (92.8%) by a discriminant function analysis. The described adult call types occurred in the context of advertisement, alarm, affiliative behavior, agonistic behavior, and locomotion. Nine of these call types were already present in infants. To aid call classification, we used the acoustic structure of calls to construct a set of call classification rules for M. zaza. Among the loud vocalizations that were candidates for acoustic monitoring we document significant sex differences in the acoustic structure of trill calls of M. zaza, and significant differences between two groups in their loud whistle calls. The vocal repertoire described here will not only form the basis for future comparative and phylogenetic studies of lemur vocalizations; it will also enable rapid identification of this species for noninvasive acoustic surveys in their natural habitat to assess and monitor population densities and establish range boundaries, thus aiding conservation efforts for this threatened lemur species.