Impact of anthropogenic factors on affiliative behaviors among bonnet macaques

Abstract

Objectives In primates, allogrooming and other affiliative behaviors confer many benefits and may be influenced by many socioecological factors. Of these, the impact of anthropogenic factors remain relatively understudied. Here we ask whether interactions with humans decreased macaques' affiliative behaviors by imposing time‐constraints, or increased these behaviors on account of more free‐/available‐time due to macaques' consumption of high‐energy human foods. Materials and methods In Southern India, we collected data on human–macaque and macaque–macaque interactions using focal‐animal sampling on two groups of semi‐urban bonnet macaques for 11 months. For each macaque within each climatic season, we calculated frequencies of human–macaque interactions, rates of monitoring human activity and foraging on anthropogenic food, dominance ranks, grooming duration, number of unique grooming partners, and frequencies of other affiliative interactions. Results We found strong evidence for time‐constraints on grooming. Macaques that monitored humans more groomed for shorter durations and groomed fewer partners, independent of their group membership, sex, dominance rank, and season. However, monitoring humans had no impact on other affiliative interactions. We found no evidence for the free‐time hypothesis: foraging on anthropogenic food was unrelated to grooming and other affiliation. Discussion Our results are consistent with recent findings on other urban‐dwelling species/populations. Macaques in such environments may be especially reliant on other forms of affiliation that are of short duration (e.g., coalitionary support, lip‐smacking) and unaffected by time‐constraints. We stress on the importance of evaluating human impact on inter‐individual differences in primate/wildlife behavior for conservation efforts.

Impact of individual demographic and social factors on human–wildlife interactions: a comparative study of three macaque species

“…spend less time engaging in social interactions, may also be forced to stay in the periphery, which may increase the time available to engage in more complex interactions with humans. This argument is supported by our detection of a weak but positive correlation between spatial position centrality and grooming social network centrality (Pearson's R: n = 319, r = 0.11, p = 0.05), and by our previous work that revealed an inverse effect of anthropogenic factors leading to a decrease in individuals' time spent grooming [42][43][44] .…”

“…Two were observed at a large Hindu temple frequented by tourists, and the other two in a recreational park on the outskirts of the city (for more details on the study site see 34 ). From July 2017 until May 2018, we studied two groups of bonnet macaques in the Thenmala Dam and Ecotourism Recreational Area (8.90 N, 77.10 E) located at the outskirts of the small town of Thenmala within the state of Kerala in Southern India (for more details on this study site see 44 ). More details related to the group sizes and compositions for all ten groups may be found in 34 .…”

“…For each focal individual macaque, we calculated various aspects of their interactions with humans. Specifically, we calculated (i) frequency of human-macaque (HM) interactions [42][43][44] , and (ii) the diversity of HM interactions defined as the number of unique behaviors shown by the focal towards humans relative to the total number of unique behaviors by all focal animals across the entire observation 65 . Thus, a focal animal that primarily showed aggression towards humans would have a lower diversity score than an animal in its same group that avoided humans, engaged in begging humans for food, and showed aggression towards humans.…”

“…In group-living animals, aspects of an individuals' social environment may also influence, or be influenced by, their behavior in anthropogenic landscapes. Studies in a variety of taxa have revealed how anthropogenic factors may influence animal social behavior, by, for example, increasing rates of within-group aggression (e.g., cichlid fish, Neolamprologus pulcher 38 ; Cuban rock iguanas, Cyclura nubila 39 ; bonnet macaques, M. radiata 40 ) and stresscoping affiliative interactions (e.g., Barbary macaques 41 ), and decreasing social grooming (e.g., rhesus macaques 42 ; long-tailed macaques 43 ; bonnet macaques 44 ), and connectedness of their social networks (e.g., spotted hyenas, Crocuta crocuta 45 ; bottlenose dolphins, Tursiops aduncus 46 ; moor macaques, M. maura 11 ). In comparison, little research has investigated the inverse effect, namely how the social characteristics of individual wild animals influence human-wildlife interactions 11 .…”

“…From a social perspective, we expected that dominance rank would be positively correlated to the above aspects of human-macaque interactions, since high-ranking individuals would also be more prone to accessing and monopolizing anthropogenic food resources 34 . Given our previous findings that social grooming among these urban macaques was subject to time-constraints imposed by their interactions with humans [42][43][44] , we expected that spatial position and social network connectedness would negatively impact the aforementioned aspects of human-macaque interactions. In particular, eigenvector centrality, through its evaluation of individuals' direct and secondary network connectedness, is an apt measure to determine whether social connectedness leads to a decrease in aspects of human-macaque interactions on account of animals' spending more time socializing (as we predict here), versus to an increase in such interactions on account of individuals with greater social connectedness or ties of support being more prone to taking risks (alternative hypothesis).…”