Vocal repertoire of wild Andean night monkeys (Aotus lemurinus) in an Andean forest in Colombia

Vocal communication is particularly important for nocturnal species as well as those living in dense forests, where visual abilities can be somewhat constrained. The Andean night monkey (Aotus lemurinus) is a nocturnal American primate living in mountain forests in the Northern Andes with scant information on its behavior and ecology. The main goal of this study is to describe the vocal repertoire of a group of wild Andean night monkeys and compare it with earlier bioacoustics studies on the only nocturnal platyrrhines. We recorded the vocal behavior of a group of night monkeys living in the eastern Andes of Colombia between August and December 2019. Based on an auditory and a visual inspection of the vocal records, and through a quantitative analysis of the acoustic parameters of the vocalizations, we were able to identify five different calls emitted by the Andean night monkey. Four of these calls are stereotyped while the fifth vocalization (Squeak) is more variable, having different forms. Additionally, one call (Acetate) was found to be unique to this species. The result of this study contributes to the scant information on the ecology and behavior of the Andean night monkey and sets baseline information on the vocal behavior of night monkeys that may be used in future studies on communication of these and other nocturnal primates.