Megan Joyce

Student Speaker | Étudiant.e
Research has shown that nonhuman primates are capable of making intentional, directional movement choices in order to solve spatial navigation problems in foraging. Here, we investigated the influence of various social (rank and conspecific competition), nonsocial (age and sex), and environmental (interspecies competition from deer) variables on route decision-making in solitary foraging trials. We conducted a multi-destination foraging experiment with 6 feeding platforms in a (4m x 8m) Z-array, recording 155 successful solitary trials by 30 identifiable individuals from a group of ~400 free-ranging Japanese macaques inhabiting forests around the Awajishima Monkey Center. Results from movement trials suggested that the macaques were able to: (1) select optimal routes (23.9% of the trials), and (2) use heuristics similar to primates in other studies (Nearest Neighbour rule 19.4%, Convex Hull 4.5%) (e.g. their movements were non-random). Our results also suggest that contextual factors led to variation in Japanese macaque route decision-making. For example, the animals used what we termed a sweep strategy (27.1% of trials), which allowed the individual to maintain vigilance on conspecifics (reducing the risk of competitors acquiring isolated food pieces), while also minimizing travel distance. We argue that this strategy was a response to the island’s topography and high intragroup competition. Our research on individual variation in route choice contributes to a better overall understanding of group-level movements and the processes underlying foraging decisions.