The vocal repertoire of the bearded capuchin (Cebidae: Sapajus libidinosus): implications for understanding the complexity of neotropical primate communication

Vocal communication is an essential aspect of primate social behaviour. The bearded capuchin Sapajus libidinosus is endemic to Brazil and some studies have described specific vocalisation types for this species; however, there is still no complete description of its vocal repertoire. Thus, this study aimed to describe the vocal repertoire of a group of S. libidinosus living in the Parque Nacional de Brasília (PNB), a protected area in the Cerrado area of Central Brazil. We carried out focal samplings and recording of vocalisations of members of a S. libidinosus troop in different behavioural contexts. The call analyses revealed 25 different types of vocalisations, and each call presented significant structural variation. We grouped these vocalisations according to the context of the emission or acoustic structure into the following categories: contact calls (contact note, infant babbling, trill, teeth- and lip-smacking, and sirena); foraging calls (chihui, grgr, and patinado); whistle series (WS; food-associated WS, long-distance WS, and inter-group encounter WS); aggressive calls (aggressive contact note, ascending rapid staccato, cough cough, and pip); calls in response to aggression (scream, squeal, and pulsed scream), sexual display calls (chuck and raspy oestrous call), and stress-related calls (alarm call/ bark, hiccup, hip, double hip, and wah wah). S. libidinosus presented a very rich vocal repertoire, revealing a pattern consistent with the repertoire of other capuchin monkey species. This is the first comprehensive description of the S. libidinosus vocal repertoire and highlights the complexity of neotropical primate communication. Vocal communication is an essential aspect of primate social behaviour. The bearded capuchin Sapajus libidinosus is endemic to Brazil and some studies have described specific vocalisation types for this species; however, there is still no complete description of its vocal repertoire. Thus, this study aimed to describe the vocal repertoire of a group of S. libidinosus living in the Parque Nacional de Brasília (PNB), a protected area in the Cerrado area of Central Brazil. We carried out focal samplings and recording of vocalisations of members of a S. libidinosus troop in different behavioural contexts. The call analyses revealed 25 different types of vocalisations, and each call presented significant structural variation. We grouped these vocalisations according to the context of the emission or acoustic structure into the following categories: contact calls (contact note, infant babbling, trill, teeth- and lip-smacking, and sirena); foraging calls (chihui, grgr, and patinado); whistle series (WS; food-associated WS, long-distance WS, and inter-group encounter WS); aggressive calls (aggressive contact note, ascending rapid staccato, cough cough, and pip); calls in response to aggression (scream, squeal, and pulsed scream), sexual display calls (chuck and raspy oestrous call), and stress-related calls (alarm call/ bark, hiccup, hip, double hip, and wah wah). S. libidinosus presented a very rich vocal repertoire, revealing a pattern consistent with the repertoire of other capuchin monkey species. This is the first comprehensive description of the S. libidinosus vocal repertoire and highlights the complexity of neotropical primate communication.