Behavior and salivary cortisol in gorillas housed in an all male group (1998)

Bettinger, T., Kuhar, C., Sironen, A. et al.

Abstract

Group-housed male gorillas were trained to voluntarily chew on the cotton plugs then return them to the caretaker ... Further analysis of these data may provide a better understanding of how the gorillas are perceiving and adapting to their physical and social environment. ... We have much to learn about the interactions of cortisol and behavior. [Training technique is not outlined.]