Saimiri play in wild, semi-wild, and captive environments

Squirrel monkey (Saimiri sciureus) play behavior was first described almost 30 years ago in studies by Frank DuMond (1968) and John Baldwin (1969, 1971). These early reports were made under the benign observation conditions of the Monkey Jungle facility near Homestead, Florida. The provisioned four acre enclosed forest, referred to in the DuMond and Baldwin papers as a ‘seminatural’ environment, was home to over 100 squirrel monkeys of all ages, as well as other primate species. The extensive descriptions of play behaviors, partner preferences, and ontogeny observed at Monkey Jungle were confirmed a few years later by Baldwin's observations of wild squirrel monkeys in Panama and Costa Rica. At the National Institutes of Health ‘animal farm’ facility at Poolesville, Maryland, I observed monkeys in indoor and outdoor enclosures and found play indistinguishable from the earlier published descriptions. Only the frequency of play, responding to environmental stressors such as food shortages, was variable. It is reassuring that play has a basic conservatism and a reliability of behavior patterns over a wide range of settings, for much of our research has come from studies of captive animals.

At about five weeks of age, infants start to reach out to each other in rudimentary play while mounted on the backs of mothers who are resting side by side. During the second month, the infants slide off their mothers' backs, and wrestle vigorously beside the mothers as they rest, or try to rest. Nervous mothers retrieve very young infants from these earliest play fights. Later, it is rare for a mother to intervene, even if the play gets noisy.