An Alternative to Woodchip as a Foraging Substrate for Tufted Capuchin Monkeys (Cebus Apella)

M.C. Riviello(a) and A. Misiti(b)
(a)Polo Biologico Integrato, C.N.R., Rome; (b)Istituto di Medicina Sperimentale, C.N.R., Rome, Italy 

To day we have a variety of techniques for environmental enrichment used in captivity to enhance the psychological health of monkeys. Many of those concern feeding strategies (Bayne et al., 1992; Reinhardt, 1993; Murchison, 1992). These techniques involve the distribution of food during the day in such a way as to make it harder to find in order to increase the feeding time.Generally, they can be applied easily in every laboratory. Nevertheless, sometimes, we have to make some changes to the original idea if we do not want to renounce it. 
We want to report own experience on the use, application and consequent modification of the woodchip. This technique of environmental enrichment consists of covering the floor to a depth of 4 cm with woodchip into which some kind of foods are mixed (Chamove and Anderson, 1982). 
Our laboratory, a short time after the introduction of woodchip, became infested with domestic mice (Mus musculus). Not wishing to give up, we decided to adequate the original idea changing woodchip with "argilla espansa". In Italy, the "argilla espansa" (expanded clay) is a material that is used in gardening to improve the permeability of the soil. It is made of little rocks, light and porous, of different size from 0.5 to 1 cm. and it could be comparable with lava rock. 
The result was excellent. it provided an ideal substrate in which the primates could search for food and mice were no longer attracted to the laboratory. Moreover the "argilla espansa" is light and therefore easily handled by the monkeys, it is porous and dries in a short time, it does not produce dust. Therefore it can be a good substitute for woodchip. We wish to encourage the use of "argilla espansa" as a substitute for woodchip in laboratories in which it is not possible to use it. In particular, with our example we want to encourage those who work with captive monkeys not to abandon the idea of an environmental device only because it could seem inapplicable in own laboratory. We believe that we must look for alternative ways of implementation of principles whose benefits have been proven.


This article originally appeared in Primate Report 42: 24 (1995).
Reprinted with permission of the Editor.