Social influence on the expression of robbing and bartering behaviours in Balinese long-tailed macaques

Authors:
Publisher website
Google Scholar
Abstract
Animals use social information, available from conspecifics, to learn and express novel and adaptive behaviours. Amongst social learning mechanisms, response facilitation occurs when observing a demonstrator performing a behaviour temporarily increases the probability that the observer will perform the same behaviour shortly after. We studied “robbing and bartering” (RB), two behaviours routinely displayed by free-ranging long-tailed macaques (Macaca fascicularis) at Uluwatu Temple, Bali, Indonesia. When robbing, a monkey steals an inedible object from a visitor and may use this object as a token by exchanging it for food with the temple staff (bartering). We tested whether the expression of RB-related behaviours could be explained by response facilitation and was influenced by model-based biases (i.e. dominance rank, age, experience and success of the demonstrator). We compared video-recorded focal samples of 44 witness individuals (WF) immediately after they observed an RB-related event performed by group members, and matched-control focal samples (MCF) of the same focal subjects, located at similar distance from former demonstrators (N = 43 subjects), but in the absence of any RB-related demonstrations. We found that the synchronized expression of robbing and bartering could be explained by response facilitation. Both behaviours occurred significantly more often during WF than during MCF. Following a contagion-like effect, the rate of robbing behaviour displayed by the witness increased with the cumulative rate of robbing behaviour performed by demonstrators, but this effect was not found for the bartering behaviour. The expression of RB was not influenced by model-based biases. Our results support the cultural nature of the RB practice in the Uluwatu macaques.
Funding Information
  • Natural Sciences and Engineering Research Council of Canada (2015-06034)
  • Alberta Gambling Research Institute, University of Alberta (G00003422)
  • University of Lethbridge Research Fund (G00002931)
  • Office of the Dean of Arts and Science at the University of Lethbridge
  • Leopold III Fund for the Exploration and Conservation of Nature (FL/JVG/vrn/1567)
  • Belgian Federation of Graduated Women

This publication has 65 references indexed in Scilit: