Use of Tools by Wild Macaque Monkeys in Singapore

Abstract

ALL known reports of tool use in wild and captive primates have been listed in two reviews1,2. Whereas agonistic tool using has been reported in many species of primates, observations of non-agonistic tool use by wild primates are surprisingly rare. Of the eleven reports of such tool use cited by Kortlandt and Kooij2, six involved apes, and of the others concerning monkeys, only one instance of the cleaning of food with leaves or other material is mentioned. A squirrel monkey swept the food over the ground with a stick, to dislodge ants. There are very few known reports of such treatment of food before eating. Crook (personal communication) has observed the cleaning of prickly pear (Opuntia) fruit by Doguera baboons, Papio doguera, in Ethiopia. The fruits are often rolled to and fro on patches of dry earth—evidently to remove the spines. Vevers and Weiner3 discussed the use of a heavy bone by a captive Capuchin to crack nuts. Kawamura4 has described the “sub-culture propagation” of potato washing in a troop of Japanese macaques, Macaca fuscata.