Gestural sequences in wild spider monkeys (Ateles geoffroyi)

To date, research on gestural communication in species other than great apes has been quite limited, especially in their natural habitat. In this study, we aimed to explore the use of gestural sequences in an understudied neotropical primate species, Geoffroy’s spider monkeys ( Ateles geoffroyi ). To this aim, we conducted behavioural observations via focal sampling on a wild group consisting of 54 individuals and collected 709 gestures, including 125 sequences and 182 gestures that were not part of a sequence. Most sequences included 2-4 gestures and were produced in the play context. Sequences often continued even after triggering the recipient’s response and were mostly produced by males and younger individuals, toward younger recipients. Only three sequences (i.e., embrace-pectoral sniff, push-present climb, grab-grab pull) occurred more than twice and were not mere repetitions of the same gesture type. Our results suggest that sequences are common in the gestural communication of spider monkeys and that they are likely the result of increased emotional arousal, rather than an attempt to convey novel meaning.