Environmental enrichment of brown capuchins (Cebus apella): Behavioral and plasma and fecal cortisol measures of effectiveness (1999)

Boinski, S., Swing, S. P., Gross, T. S. et al.

Abstract

Plasma cortisol was significantly predicted by the proportions of both normal and abnormal behaviors; as the proportion of normal behavior increased, the plasma cortisol measures decreased. ... In light of our experimental findings that a variety of EE [environmental enrichment] was more efficacious than a single source, we established minimum standards for acceptable EE for singly housed brown capuchins that emphasized an abundance and diversity of physical EE: three toys per cage, two or three plastic recycled bottles, a wood block for chewing, a perch chain, daily access to a foraging device, and direct daily social interaction with animal technicians.