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Primates. 2017 Oct;58(4):505-516. doi: 10.1007/s10329-017-0611-1. Epub 2017 May 17.

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

Author information

1
Behavioural Biology Unit, University of Liège, 22 Quai Van Beneden, 4020, Liège, Belgium. fbrotcorne@gmail.com.
2
Department of Psychology, University of Lethbridge, Lethbridge, AB T1K3M4, Canada. fbrotcorne@gmail.com.
3
Conservation Biology Unit, Royal Belgian Institute of Natural Sciences, Brussels, 1000, Belgium. fbrotcorne@gmail.com.
4
Behavioural Biology Unit, University of Liège, 22 Quai Van Beneden, 4020, Liège, Belgium.
5
Department of Psychology, University of Lethbridge, Lethbridge, AB T1K3M4, Canada.
6
Department of Anthropology, University of Notre Dame, Notre Dame, 46556, IN, USA.
7
Primate Research Center, Universitas Udayana, Denpasar, 80361, Bali, Indonesia.
8
Conservation Biology Unit, Royal Belgian Institute of Natural Sciences, Brussels, 1000, Belgium.

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.

KEYWORDS:

Anthropogenic influences; Balinese macaques; Cultural behavior; Demographic correlates; Token exchange

PMID:
28516338
DOI:
10.1007/s10329-017-0611-1
[Indexed for MEDLINE]

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