Note Repertoire and Age-sex Differences in the Vocalizations of Sapajus libidinosus

AbstractDocumenting the size and variety of a species’ vocal and note repertoires is fundamental for a better understanding of the diversity, function, and importance of primate calls. Sapajus libidinosus is widely known for its cognitive complexity, including tool use, and is therefore expected to present a large and complex acoustic repertoire. We describe the acoustic communication of S. libidinosus and test for differences in vocal parameters between contexts, sexes, and developmental stages. We also present the species’ note repertoire and its acoustic parameters. We recorded and extracted spectral and temporal parameters of 265 calls, with the sender’s sex and developmental stage, and the context of call emission. We identified 16 calls composed of eight different notes, with four calls presenting a combination of different notes. Juveniles presented calls with higher frequency and shorter duration than adults. Males presented calls with higher frequency and longer duration than females. These differences in acoustic proprieties may relate to traits, such as body size, and social roles. The use of the same note in different calls could represent an important evolutionary strategy in primates, allowing the creation of multiple calls without mechanical or neurological constraints. This understanding of note use, and its apparent combinatorial patterns, provides the foundation for future investigations of whether the underlying patterns indicate syntactic rules and whether they convey complex semantic information.DOI: 10.1007/s10764-025-00513-2