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Digest 12

 

"Destructible Toys as Enrichment for Captive Chimpanzees"

Authors of original article: Linda Brent and Adam Stone
Originally published in Journal of Applied Animal Welfare Science
Volume I, Number 1, 1998*

The authors studied the behavior of nine chimpanzees in a biomedical laboratory with regard to eight different destructible objects placed in the chimpanzees' cages as toys: a vinyl shoe, a vinyl soda bottle, a plastic cup, a plastic block, a plastic bowling pin, a bottle brush, a 3-liter plastic bottle containing some dry corn, and a 1-foot square piece of cloth fleece. The chimpanzees, aged 4.5 to 34 years, were kept in individual 100-square-foot cages with built-in benches and perches, rigid balls, other durable toys, and color televisions. The questions were whether and to what degree destructible toys would provide enrichment to chimpanzees kept in a small, sterile, and unstimulating environment, prevented from socializing with each other-although they could see each other-and from otherwise engaging in their natural behavior and living natural chimpanzee lives in natural chimpanzee habitat.

Often, permanent, almost-indestructible toys are placed in chimpanzees' laboratory cages for environmental enrichment. Durable toys, not having to be replaced often, have been seen as minimizing costs, personnel time, sanitation, and animal-safety concerns such as that chimpanzees might ingest parts of toys they are able to break. Chimpanzees' use of permanent toys, however, tends to decrease over time. Being complex animals adapted to complex and varied environments, chimpanzees enjoy novelty so rotating durable toys has been found effective. It made sense, then, to observe the use of inexpensive, easily obtainable temporary objects.

The authors assessed the usefulness of destructible objects by comparing the chimpanzees' responses to the introduction of one destructible toy at a time with their responses to the introduction of all eight at once. Toy introductions took place in 15-minute trial periods. Observers noted frequency of contact with and degrees of damage to each toy. Behaviors with regard to the toys included biting the toy, rubbing the toy on oneself, throwing the toy, and 17 more. Each toy was removed when it was destroyed or when a chimpanzee never touched the toy in 4 trials.

One chimpanzee rarely touched any of the toys. The other eight used them a lot and destroyed them quickly. The number of uses was much higher when toys were presented one at a time than all at once. The number was higher on the first introduction than on later ones. On average, the toys lasted from 2.3 to 4.5 days, the more rigid plastic items having to be removed from the cages much sooner than the flexible cloth and vinyl ones. The chimpanzees used the eight destructible toys much more than their permanent cage toys or their televisions. The authors concluded that providing one destructible toy at a time is more effective and efficient for enrichment of chimpanzees' laboratory existences than providing many such toys at a time and that this method is worthy of laboratory workers' consideration even though costs in money and staff time must be analyzed in each situation. As long as chimpanzees and other highly intelligent animals are kept in laboratories, it is hoped that staff will work hard to minimize their boredom and depression.
 

*Available from Psychologists for the Ethical Treatment of Animals, P.O. Box 1297, Washington Grove, MD 20880-1297; 301-963-4751.

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