Wisconsin Regional Primate Research Center
Author describes simple wood and plastic perches that have been tested successfully with several hundred rhesus monkeys and forty stumptailed monkeys of both sexes and various ages over the past three years at Wisconsin Regional Primate Center.
It is often argued that enriching the barren cages of nonhuman primates in laboratories cannot be afforded by the biomedical community. Admittedly, it would probably be too expensive for most institutions to provide several hundred caged primates with televisions, radios, electrical manipulanda, or food puzzles in an attempt to distract them and hence reduce their boredom. From the human point of view, such expensive gadgets may be attractive. From the monkey's point of view, however, environmental enrichment need not be fancy, but it should provide species-adequate stimulation for the expression of species-typical behavior patterns. A simple wooden (deciduous tree -branch) or plastic (PVC) perch is such an enrichment object. A perch costs little but provides an optimal cage enrichment for several reasons:
1. A perch provides the opportunity for species-typical behavior, i.e. sitting in an elevated position.
2. Sitting in an elevated position may increase a monkey's feeling of security by providing it a better visual control over the environment outside the cage.
3. A perch opens up a new cage dimension for the animal and thus increases its usable cage space (Figure 1)..
4. A perch does not lose its attractiveness for the caged animal over time. Rhesus monkeys that were exposed to PVC pipes or oak branches for one year continued to spend about 1/4 of their time sitting or walking on them (Reinhardt, 1989, Reinhardt, 1990).
5. A perch is particularly attractive for animals during the daily cleaning of their cages because they offer a dry, comfortable place to sit while the floors of their cages are sprayed with water (Figure 2).
6. A perch can be easily installed (Reinhardt, 1987; Reinhardt and Pape, 1991).
A perch for macaques should be round and have a diameter of 4-8 cm to facilitate comfortable sitting. It should be installed at such a height that an adult animal not only can sit on it but also freely move under it.
Wooden and plastic perches have been tested successfully by several hundred rhesus monkeys (Macaca mulatta) and 40 stumptailed monkeys (Macaca arctoides) of both sexes and various ages over the last 3 years at the Wisconsin Regional Primate Research Center. Perches have proven an inexpensive, simple, yet effective environmental enrichment for these species.
Figure 1 Installing a perch is an inexpensive way to increase the usable cage space for macaques.
Figure 2 A perch offers the monkey a dry, comfortable place for sitting
and for checking the environment outside the cage.
1. Reinhardt, V. (1987). Improved installation method for branches as cage enrichment. Laboratory Primate Newsletter. 26(3). p. 1.
2. Reinhardt, V. (1989). Evaluation of the long-term effectiveness of two environmental enrichment objects for singly caged rhesus macaques. Lab Animal. 18(6). pp 31-33.
3. Reinhardt, V. (1990). Comparing the effectiveness of PVC perches versus wooden perches as environmental enrichment objects for singly caged rhesus monkeys. Laboratory Primate Newsletter. 29(l). pp. 1-2.
4. Reinhardt, V. and Pape, R. (1991). An Alternative method for primate perch installation. Lab Animal. 20(8). pp. 47-48.
This article originally appeared in Humane Innovations and Alternatives in Animal Experimentation 4, 134-135 (1990). Reprinted with permission of the Editor.