Behaviour 2019
A true monkey wrench? Multipurpose tool use and manufacture by wild bonnet macaques Macaca radiata
Arijit Pal1, Kakoli Mukhopadhyay2, Jean-Baptiste Leca1,3, Anindya Sinha1,2,4,5. 1Animal Behaviour and Cognition Programme, National Institute of Advanced Studies, Bangalore, Karnataka, India; 2Dhole’s Den Research Foundation, Bandipur National Park, Kaniyanapura Village, Karnataka, India; 3Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada; 4Centre for Neuroscience, Indian Institute of Science, Bangalore, Karnataka, India

Our long-term studies on wild bonnet macaques in southern India provide evidence of five adult individuals¾one male and four females¾from three distinct populations manipulatively using sticks as tools in several non-foraging contexts. The females displayed vaginal grooming while the male independently performed urethral grooming, wound inspection and dental grooming. In all these instances, the actor achieved a certain goal by systematically controlling a tool to mediate a desired change in another object, a part of its own body. The macaques often manipulated these naturally available objects and modified their physical properties, providing clear evidence of tool manufacture. The adult male occasionally carried the tool in his mouth to reuse it later, unique evidence of a non-ape primate planning for the future. The ability of these macaques to modify and use different tools to achieve similar ends arguably constitutes intelligent object manipulation, possibly mediated by a perception of causality. Such examples of tool use and manufacture in contexts other than foraging should prompt us to develop novel experimental paradigms of object manipulation by captive nonhuman primates.