- Infants and juveniles, whose social development will be carefully monitored.
- Animals that cannot be socially housed (especially those held in environments that limit visual, auditory, tactile, or olfactory interaction with conspecifics or members of other compatible species), for which enrichment strategies will be specially tailored.
- Nonhuman primates in psychological distress, as determined by behavior or appearance.
- Nonhuman primates participating in approved animal study protocols that require restricted activity for longer than 12 hours.
B. Pair- and Group-Housed Squirrel Monkeys
Environmental enhancement for pair- and group-housed squirrel monkeys is necessary but sometimes difficult. Squirrel monkeys are vastly different from macaques in their desire to manipulate toys and to maintain an interest in novel aspects of their environment. The procedures adopted by USE consider the natural behaviors of squirrel monkeys and the special husbandry procedures that they require.
- Perches, Swings, and Cage Complexities
- Perches. Squirrel monkeys are arboreal primates and typically spend most of their time in middle-level canopy of the South American rain forest. The genus can make maximal use of three-dimensional space. USE provides each cage with multiple levels of perches, which were determined from reference to the literature and by testing to be optimal for the species. (Scientific articles on the husbandry and housing of squirrel monkeys by USE veterinarians and behavioral scientists have contributed to the well-being of this species.)
- Swings. Given the squirrel monkey's arboreal abilities, each social cage is provided with at least one swing consisting of plastic chain, looped PVC pipe, or other similar material.
- Hide or nest boxes. Direct eye contact is an aggressive encounter for squirrel monkeys (as it is for macaques and many other species). USE provides "hide boxes" in each social cage to allow a submissive animal refuge from an aggressive animal. The use of hide boxes has been shown to reduce the frequency of fight-related injuries in Saimiri (see appended abstract published by USE scientists).
- Forage for food. Squirrel monkeys are foragers that spend up to 75% of their time moving through the forest eating. To encourage foraging in indoor-outdoor social cages, food is scattered in the litter on the cage or pen floor after daily cleaning. This forces the animals to move through the cage to select their food. Squirrel monkeys do not use puzzle feeders and grooming devices, which do not simulate food presentation for this species.