The behavior of singly-caged, yearling rhesus monkeys is affected by the environment outside of the cage (1995)

Schapiro, S. J., Porter, L. M., Suarez, S. A. et al.

Abstract

Yearling rhesus monkeys singly caged in an outdoor building with exposure to social groups and to variable environmental conditions spent less time inactive and playing, and more time feeding, drinking, and behaving abnormally [in response to fear-inducing husbandry manipulations in social groups] than did similar monkeys singly caged in indoor rooms without access to social groups or environmental variation.