Evaluation of the preference to and behavioral effects of an enriched environment on male rhesus monkeys (1992)

Bayne, K., Hurst, J. K., Dexter, S. L.

Abstract

With simultaneous exposure, the single-housed subjects spent the greatest portion of the interactive time [30 minute-observation sessions] on the perch [16.8%], the second greatest amount of time spent divided approximately equally between interacting with the Kong [5.0%] and Tug-A-Toy [4.9%], and the least amount of time spent manipulating the grooming board [0.4%]. No statistically significant decline in use of (or habituation to) the enrichment devices was detected. A galvanized steel perch (Lab Products) ... was placed approximately 20 cm [emphasis added] off the floor of the cage, parallel to the side wall (p. 39).