Zoos, enrichment, and the skeptical observer (1998)

Morgan, K. N., Line, S. W., Markowitz, H.

Abstract

Increasing cage size as a means by which to enrich and enhance an animal habitat may not be worth the cost, at least under conditions in which the size of the cage is the only aspect that is altered. ... Pairing animals may have mixed effects on psychological well-being: decreasing abnormal behavior and increasing prospects for prosocial interactions while at the same time contributing to the stress of captivity by increasing an individual's exposure to inescapable aggression and potential injury. ... Social pairing is associated with high health risks to monkeys. ... Mere access to simple toys had minimal effects on behavioral indicators of well-being [reducing frequency of abnormal behavior or increasing activity in single-housed animals]. ... Interactive devices appear to sustain decreases in abnormal behaviors.