Neu, K., Howell, S., Fritz, J. et al. 2000. Rigid plastic balls as environmental enrichment: A novel presentation. The Newsletter 11(2), 1-2.

At the Primate Foundation of Arizona (PFA), we provide many different types of both destructible and indestructible objects, but seldom provide rigid plastic balls. They are frequently thrown about the enclosure during displays and have damaged the cage mesh. We sought a solution to avoid this problem and still use the rigid plastic balls for environmental enrichment. PFA outdoor cages have a 23cm alley-way between them to prevent possible wounding among members of adjacent groups, especially newcomers to these groups. We placed a rigid plastic ball in this alley-way area between two groups. Both groups of animals were able to manipulate (roll) the ball up and down the alley-way through the mesh. However, the chimpanzees were unable to toss the ball about during active displays. While behavioral observation data suggest that the addition of the ball had no significant effect on behavior, ad libitum data [collected during the first 40 minutes both groups had access to the ball] suggest the ball was used by most individuals and was effective in initiating positive social interactions between adjacent cagemates.