For monkeys at the WaNPRC, environmental enrichment is a part of daily life. This is because enrichment is widely believed to improve the psychological health of nonhuman primates. Attention to the psychological well-being of laboratory primates derives from ethical concerns for the welfare of our fellow creatures and from a need to ensure a healthy subject for research. The 1985 amendment to the 1966 Animal Welfare Act introduced the concept of psychological well-being into Federal law. It led to the U. S. Department of Agriculture's 1991 Animal Welfare Standards requiring research institutions, zoos, and other facilities with captive nonhuman primates to formulate Environmental Enhancement Plans to enrich the primates' physical environment and address their social needs. Although the USDA provides some guidelines, each institution develops its own plan. Facilities vary in the types of primates they house, and appropriate enrichment varies according to species' cognitive abilities, social organization, locomotor behavior, manipulative skills, and other characteristics. Our Environmental Enhancement Plan is tailored to the four monkey species commonly needed in research at the WaNPRC: P. cynocephalus, M. nemestrina, M. fascicularis, and M. mulatta.

The University of Washington's Environmental Enhancement Plan was developed by WaNPRC staff and the UW Attending Veterinarian. Every WaNPRC monkey participates in the Environmental Enhancement Plan, as required by Federal law. On a day-to-day basis, the Environmental Enhancement Plan is overseen by the Primate Center's Psychological Well-being Program. PWB Program staff and animal husbandry staff provide most of the enrichment to the monkeys. The remainder is given by researchers and veterinary staff.

The WaNPRC Environmental Enhancement Plan includes several types of enrichment.

Perches:
To address their arboreal nature, we provide laboratory monkeys access to a place to sit or climb above floor level. Individual cages have perches that a monkey can sit or lie upon, or use for climbing up and down. Monkeys in group compounds use climbing structures made from recycled caging and plastic barrels. Infants that must be raised in the nursery have a cloth-covered swinging device upon which they can cling and perch.

Toys:
Macaques and baboons have hands that resemble our own, and they can spend many minutes at a time manipulating their environment. To provide opportunities for manipulation, we provide monkeys with cage toys, usually tough dog toys like the Kongr and Gummar Plaque Attacker dental ball (which, because of its shape, we call the "multilobe"). Although monkeys sometimes toss the toys around, the most common activity is to bite and gnaw them. Psychological Well-being Program carefully evaluates the types of toys before widespread adoption because some are unsafe for monkeys or wear out too quickly to be cost effective. The teeth of macaques and baboons are strong and can make interesting shapes of the toys.

Four sizes of Kong toys

New and monkey-modified Plaque Attacker "multilobe"

The monkeys periodically receive other types of enrichment to manipulate, hung on the outside of their cages, such as mirrors and devices with furry material to stimulate grooming behavior.

Food Treats and Foraging Experiences:
Food treats and foraging experiences enhance the psychological well-being of laboratory monkeys in various ways. They stimulate varied taste experiences, encourage different manipulative and foraging behaviors, vary the daily routine, and provide positive social contact with the human caregiver who delivers them. They also offer a variety of food types resembling the annual diversity found in the wild, where macaques and baboons may eat more than 100 different kinds of foods during a year.

The Psychological Well-being Program takes pride in the variety of food treats and foraging items provided to the monkeys. In accordance with guidelines provided by the USDA, we distinguish between a simple food treat and a foraging experience. A food treat is any edible item providing variety from dry biscuit diet and given in a small amount. A produce food treat is a fresh fruit or vegetable treat. More than 60 different kinds have been given to the monkeys, from Apples to Zucchinis. Non-produce food treats include cereals, nuts, dried fruits, dried pasta, among others.

Social Enrichment:
In their natural habitats, baboons and macaques live in social groups. A diverse repertoire of communicative facial expressions, postures, and vocalizations attest to their social nature. In captivity, these social needs must be addressed. Laboratory monkeys are sometimes housed in breeding groups of a size resembling wild groups.

More often, laboratory monkeys are housed in smaller groups with only one breeding male, in juvenile groups, or in pairs, usually of the same sex unless pregnancies are wanted. At the WaNPRC, we have developed an alternative to group or pair-housing-the grooming-contact cage-which is compatible with many research protocols for which group-housing would not be appropriate. Monkeys are in separate cages, but widely spaced vertical bars allow them to engage in social grooming and other tactile contact. The bars prevent aggressive pursuit or one monkey monopolizing the other's food. When two sets of grooming-contact bar panels separate a male-female pair, pregnancy is prevented.

Grooming-contact cage

Longtailed macaques in grooming-contact cages

For research projects for which tactile social contact is not possible, for example those involving infectious disease studies, an exemption may be granted by the Institutional Animal Care and Use Committee. Primates also may be excluded from physical social contact by the attending veterinarian for reasons such as overly aggressive behavior, physical debilitation, or disease. In such cases, the animals' social needs are met through visual contact with others of the same species and positive interactions with knowledgeable human caregivers.

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