How urban living and social centrality are linked to personality in a synanthropic primate (Macaca fascicularis)

Human activities threaten wildlife by altering habitats and exposing animals to unpredictable urban environments. Emerging research suggests that personality may play a key role in coping with urban challenges. In this study, we investigated how habitat and network sociality are linked to personality in long-tailed macaques (Macaca fascicularis), a synanthropic primate species, in Bali (Indonesia). Behaviors among individuals are known to vary with social positions and environmental pressures. Therefore, we predicted that certain personality traits would be associated with more central positions and that some would be more prominent in urban versus forest environments. Using 466.55 hours of focal observations on spontaneous behaviors, we gathered behaviors into several personality dimensions using PCAs. We first compared two personality traits – Assertiveness (received submission and display) and Dominance (received grooming) – between two groups inhabiting contrasting environments: 11 individuals in a protected forest and 51 in an urban habitat. We then assessed how social centrality correlated with personality traits, including additional dimensions: Anxiety (emitted submission, activity and object handling) and Assertiveness Towards Humans (interactions with humans). We found that individuals’ scores on neither Assertiveness nor Dominance differed between the habitats. Conversely, our results showed that social centrality strongly predicted some personality traits. More central females displayed lower Anxiety scores, whereas central males showed higher Anxiety. Peripheral individuals were less assertive with conspecifics but more assertive towards humans. While further group-level comparisons are needed, these preliminary results offer valuable insights into how social dynamics mediate behavioral responses – a crucial mechanism for coping with anthropogenic pressures.