Williams, L. E., Abee, C. R., Barnes, S. R. et al. 1988. Cage design and configuration for an arboreal species of primate. Laboratory Animal Science 38, 289-291.

Squirrel monkeys preferred a poly-vinyl-chloride pipe perch (rigid) over rope perches (non-rigid). For an arboreal animal, a higher perch may be perceived as safer. Additional perches decreased the propensity for development of tail ulcers associated with floor contact. With only one perch level, males were forced to spend a large percentage of their time sitting on the floor rather than the main perches [which were occupied by females]