The vocal repertoire of golden-faced sakis, Pithecia chrysocephala, and the relationship between context and call structure

Vocalizations are a vital form of communication. Call structure and use may change depending on emotional arousal, behavioral context, sex, or social complexity. Pithecia chrysocephala (golden-faced sakis) are a little-studied Neotropical species. We aimed to determine the vocal repertoire of P. chrysocephala and the influence of context on call structure. We collected data June–August 2018 in an urban secondary forest fragment in Manaus, Amazonian Brazil. We took continuous vocal recordings in 10-min blocks with 5-min breaks during daily follows of two groups. We recorded scan samples of group behavior at the start and end of blocks and used ad libitum behavioral recording during blocks. We collected 70 h of data and analyzed 1500 calls. Lowest frequencies ranged 690.1–5879 Hz in adults/subadults and 5393.6–9497.8Hz in the only juvenile sampled. We identified eight calls, three of which were juvenile specific. We found that, while repertoire size was similar to that of other New World monkeys of similar group size and structure, it also resembled those with larger group sizes and different social structures. The durations of Chuck calls were shorter for feeding contexts compared to hostile, but frequencies were higher than predicted if call structure reflects motivation. This finding may be due to the higher arousal involved in hostile situations, or because P. chrysocephala use Chuck calls in appeasement, similar to behavior seen in other primates. Call structures did not differ between sexes, potentially linked to the limited size dimorphism in this species. Our findings provide a foundation for further investigation of Pithecia vocal behavior and phylogeny, as well as applications for both captive welfare (stress relief) and field research (playbacks for surveys)