Use of nylon balls as behavioral modifier for caged primates (1985)

Renquist, D. M., Judge, F. J.

Abstract

The [single-housed] animals play with the ball [Nylaball?] by rolling it in the cage. Adult females hold it as a surrogate infant. Stumptail macaques often chew the ball. ... The inert nature of the nylon renders it nontoxic, and any chewed particles pass through the intestinal tract.