Environmental Enrichment in the 21st Century

Abstract

More than a quarter of a century has elapsed since the Animal Welfare Act mandated that research facilities develop and follow a plan to promote the psychological well-being of captive primates. Since passage of this law, considerable effort and resources have been directed to designing environmental enrichment strategies in an effort to improve animal welfare. These plans typically consist of environmental enrichment and socialization efforts. While environmental enhancement has undergone a great deal of improvement in the past 25 years, it should be viewed as a continual work in progress, which takes advantage of emergent and future technologies. In this review, we discuss the objectives of the environmental enhancement plan along with relevant outcome measures, as well as ongoing challenges, costs, and benefits. We then review various enrichment strategies and assess their efficacy in meeting goals and objectives. Finally, we look forward to consider what the future might hold for environmental enrichment of nonhuman primates used in research.

Keywords: animal welfare; nonhuman primate; psychological well-being; social housing.

Figure 1

(A) Examples of toys and structures for climbing, resting, and hiding for group-housed rhesus macaques (photo courtesy of the Oregon National Primate Research Center). (B) Example of a hammock for a rhesus macaque (photo courtesy of the University of Massachusetts, Amherst).

Figure 2

Caged rhesus macaque with a “porch” (photo reprinted from Gottlieb et al. 2014 [Figure 1, p 654] with permission from the Journal of the American Association of Laboratory Animal Science).

Figure 3

Cynomolgus macaques with a tunnel connecting upper- and lower-level cages (photo courtesy of the Oregon National Primate Research Center).

Figure 4

Rhesus macaque using iPad enrichment (photo courtesy of the University of Massachusetts, Amherst).