Use of space and manipulable objects in chimpanzees: individual differences in response to environmental enrichment (2003)

Smith, K., Tobery, T., Erwin, J.

Abstract

Twenty-five captive-born chimpanzees were housed in glass-walled biocontainment suites containing resting benches and climbing structures. Thirteen of these animals were individually housed; 12 were paired or grouped. ... In a separate study, five of the individually housed chimpanzees were studied more intensively. Each animal simultaneously received three blankets each. .. Only 13% of subjects slept on resting benches, and all who did so were individually housed. All socially housed individuals slept in contact with another chimpanzee. Blanket contact increased across weeks in 4 of the 5 chimpanzees, and declined in none. ... 1. Individuals differed in use of, and preferences for, environmental features. No chimpanzee habituated to any blanket type provided, suggesting that novelty is not a necessary component of enrichment. Contact with a conspecific was the most universally employed environmental option.