Pruetz, J. D. E., McGrew, W. C. 2001. What does a chimpanzee need? Using natural behavior to guide the care and management of captive populations. In: Special Topics in Primatology, volume 2. The Care and Management of Captive Chimpanzees. Brent, L. (Ed.). The American Society of Primatologists: San Antonio, TX, 16-37.

Their tendency toward natural behavior is probably little changed from their wild counterparts, despite the overwhelming influence of captivity on behavior... From a chimpanzee's point of view, it would be better to stimulate behavior characteristics of the natural environment of this species in the wild, instead of seeking to simulate the appearance or aesthetics of nature.</p>