Macaques conceal food from alpha males by inhibiting interest in it, refraining from approaching it or looking at it

Factors influencing deceptive behaviours in Tonkean macaques (Macaca tonkeana). Charlotte Canteloup et al. https://doi.org/10.1163/1568539X-00003443

Abstract: The complex social environments of primates create opportunities for engaging in tactical deception, especially for subordinate individuals. We analysed the behaviour of subordinate Tonkean macaques with dominant conspecifics in an experimental food competition context. The subordinate macaque could see two pieces of food in a test area, but only one piece was visible to the dominant. Both individuals were released into the test area at the same time or with the subordinate given a short head start on the dominant. Here, based on video analysis of the subordinates’ behaviours, we describe and classify functionally deceptive behaviours displayed by subordinates, and report factors that influenced these behaviours. Subordinates used several types of tactical deception, including concealment and distraction, especially when paired with competitors of much higher social rank, and they obtained the hidden food more frequently when they used a combination of tactics rather than only one.

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The most frequently used tactic was concealment by inhibiting interest in object, either by refraining from approaching the food, or ‘freezing’ (see Video 1 in the online edition of this journal, which can be accessed via http://booksandjournals.brillonline.com/content/journals/1568539x), sometimes avoiding looking at the food. In this kind of concealment, subordinates acted as if they were unaware of the presence of food, for example by not entering the test area, or entering and then stopping or sitting down. The most parsimonious interpretation of this tactic is that the subordinate was simply inhibited by the dominant’s presence and/or gaze (behaviour reading hypothesis; e.g., Povinelli & Vonk, 2003), rather than actively refraining from approaching despite knowing that the dominant was unaware of the food (mindreading hypothesis; e.g., Call & Tomasello, 2008). It is conceivable that most cases of simple concealment by inhibiting interest reflect simple behavioural inhibition induced by the presence of a dominant competitor.

Concealment by inhibiting interest was used on its own or combined with other tactics such as concealment by hiding. In concealment by hiding, subordinates behaved so as not to be seen by the dominant. For example, they refrained from immediately entering the test area, or headed for the hidden food when the dominant’s back was turned (see Video 2 in the online edition of this journal, which can be accessed via http://booksandjournals. brillonline.com/content/journals/1568539x) or after the dominant left the test area. Similar behaviour has been described in the context of sneaky matings in long-tailed macaques (Macaca fascicularis: Overduin-de Vries et al., 2015), and geladas (Theropithecus gelada: le Roux et al., 2013), done out of view of the alpha male. We previously reported that subordinate Tonkean macaques moved preferentially for hidden food when released simultaneously or slightly before the dominant, and proposed that they are capable of visual perspective-taking (Canteloup et al., 2016). In this context, concealment by hiding could reflect an active attempt by subordinates to be out of view of the dominant. However, we cannot exclude the lower-level explanation that subordinates merely reacted to the dominant’s gaze, without perspective-taking (Canteloup et al., 2016).