How do individual behaviors based on visual and auditory cues facilitate spatiotemporal coordination in collective movement of patas monkeys (Erythrocebus patas)?

Collective movement requires individuals to coordinate their behaviors across time and space. Recent advances in GPS tracking have enabled the recording of whole-group movements and estimation of group cohesion. However, integrating individual behavior with group-level dynamics remains a developing approach. In this study, we combined GPS tracking with behavioral observations to examine visual monitoring and calling related to collective movement in a group of wild patas monkeys ( Erythrocebus patas ), with a focus on sex-specific patterns. Females engaged in visual monitoring when fewer juveniles were nearby, followed by increased juvenile proximity, suggesting a role in maintaining spatial cohesion with juveniles. In contrast, the male monitored visually when out of temporal synchrony with females, and his monitoring increased velocity differences at the future time. This implies that the male may be engaging in monitoring primarily as a form of vigilance against predators or conspecific groups, possibly contributing to the protection of females as potential mating partners, rather than to maintain temporal synchrony with them. Interestingly, female contact calls were associated with increased others’ velocity, particularly under conditions where the caller and others were previously moving at similar velocity. This suggests that females may produce calls with the goal of accelerating the movement of other individuals, consistent with intentional communication. Over all, our findings suggest that visual monitoring and calling function in context-dependent ways and highlight the importance of integrating movement dynamics, intentional communication and behavioral context to better understand the mechanisms of collective coordination in group-living animals.