Intergroup variation in robbing and bartering by long-tailed macaques at Uluwatu Temple (Bali, Indonesia)

Abstract

Robbing and bartering (RB) is a behavioral practice anecdotally reported in free-ranging commensal macaques. It usually occurs in two steps: after taking inedible objects (e.g., glasses) from humans, the macaques appear to use them as tokens, returning them to humans in exchange for food. While extensively studied in captivity, our research is the first to investigate the object/food exchange between humans and primates in a natural setting. During a 4-month study in 2010, we used both focal and event sampling to record 201 RB events in a population of long-tailed macaques (Macaca fascicularis), including four neighboring groups ranging freely around Uluwatu Temple, Bali (Indonesia). In each group, we documented the RB frequency, prevalence and outcome, and tested the underpinning anthropogenic and demographic determinants. In line with the environmental opportunity hypothesis, we found a positive qualitative relation at the group level between time spent in tourist zones and RB frequency or prevalence. For two of the four groups, RB events were significantly more frequent when humans were more present in the environment. We also found qualitative partial support for the male-biased sex ratio hypothesis [i.e., RB was more frequent and prevalent in groups with higher ratios of (sub)adult males], whereas the group density hypothesis was not supported. This preliminary study showed that RB is a spontaneous, customary (in some groups), and enduring population-specific practice characterized by intergroup variation in Balinese macaques. As such, RB is a candidate for a new behavioral tradition in this species.

Interactions with humans impose time constraints on urban-dwelling rhesus macaques (Macaca mulatta)

“…That is, people can pose either a real or potential threat to the macaques and therefore cause the animals to frequently avoid humans (Chauhan & Pirta, 2010a, b;Priston & McLennan, 2013). Alternatively, macaques are frequently provisioned by people and some macaques beg for food, investigate people's belongings or steal objects in order to barter the stolen item for food Brotcorne et al, 2017;. To determine the nature of the relationship between rates of interaction with humans and monitoring of human activity, as two potentially interdependent sources of time constraints, we first tested whether macaques' monitoring time was affected by total rates of human-macaque interactions as well as by four specific types of interactions: (1) human-to-macaque aggression, (2) macaques avoiding people in a non-aggressive context (e.g., a person walking by or approaching the macaque), (3) humans providing food to the macaques and (4) macaques initiating non-aggressive interactions with people (prediction 1a), We then assessed whether total rates of human-macaque interactions and the four above-mentioned specific types of human-macaque interactions significantly reduced macaques' resting (prediction 1b) and grooming time (prediction 1c).…”

The lemur baseline: how lemurs compare to monkeys and apes in the Primate Cognition Test Battery

“…In the causality scale , lemurs performed as well as both monkey species, but all monkeys and lemurs were outperformed by chimpanzees, who excelled in the tool use task. Even natural tool users, such as orangutans and long-tailed macaques ( Brotcorne et al, 2017 ; Van Schaik, Fox & Fechtman, 2003 ), hardly solved this task ( Schmitt, Pankau & Fischer, 2012 ). It required the ability to use a stick to rake a food reward into reach, which might have been too challenging for species exhibiting either a medium (baboons, macaques) or low (lemurs) level of precision grip ( Torigoe, 1985 ).…”

“…In the social learning scale neither lemurs, nor baboons or long-tailed macaques solved the task. However, long-tailed macaques exhibit cultural variation in stone handling techniques in the wild, indicating that they are able to learn socially ( Brotcorne et al, 2017 ). The ability to learn socially has also been reported in ring-tailed and ruffed lemurs (e.g., Kappeler, 1987 ; Kendal et al, 2010 ; O’Mara & Hickey, 2012 ; Stoinski, Drayton & Price, 2011 ), but remains unstudied in mouse lemurs.…”

The Escalating Effects of Wildlife Tourism on Human–Wildlife Conflict

“…Despite these negative impacts, some scholars regard human–macaque interactions in tourism as opportunities that have stimulated the evolution of macaques [ 18 ]. Evidence for this point of view is the robbing and bartering behavior developed by long-tailed macaques at Uluwatu Temple, Indonesia [ 60 ]. The macaques have learned to steal inedible objects such as glasses and hats from tourists and barter the objects for food with the staff.…”