Uprooted trees facilitate the psychological well-being of captive chimpanzees

After the introduction of uprooted trees to their environment, the behavior of 28 socially housed, laboratory chimpanzees (Pan troglodytes) was studied for five months. Subjects used the tree during 41.9% of the data points collected during the first day trees were introduced. Thereafter, the mean for tree use dropped to 3.5% and remained fairly consistent. Immature subjects used the trees significantly more than did adult subjects, as measured by the Mann‐Whitney U‐test. No sex difference was detected. The trees elicited a variety of species‐appropriate behaviors. Increasing the similarity between the behavior of captive and wild chimpanzees can be viewed as promoting the psychological well‐being of the captive animals.