Responses to Scent Marks in a Wild Group of Leontocebus Weddelli: Insights for Sexual Communication

Olfaction is a key sensory modality in primate sexual communication; yet, studies examining scent marking behavior and its sex-biased expression remain relatively rare. Furthermore, even fewer have examined the responses elicited by these markings. In this study, we investigated the response behaviors to scent marking in wild tamarins. We hypothesized that scent serves a sexual communication function to facilitate mate attraction and/or mate guarding, and predicted differences in the number and type of responses by males and females. We further predicted increased response rates at the periphery of the home range, where reproductive competition with neighboring groups may be higher. We focused on a group of wild saddleback tamarins (Leontocebus weddelli) and recorded investigatory and overmarking responses to each observed scent marking event, together with the GPS location where the scent was deposited. We found that scent marks of the single breeding female received the highest number of responses, consistent with a role of olfaction in mate attraction. Additionally, most overmarks were performed by primary breeding males in response to female scent marks, suggesting that odor may play a role in mate guarding, potentially mediating male-male competition. However, location within the home range was not associated with the likelihood of responses. Overall, olfactory communication within the social group occurred primarily between the breeding female and the breeding males, with males responding to her scent marks through both investigation and overmarking. Our results provide new data on scent-based communication and putative reproductive dynamics among group members.