Cage design attenuates display patterns of male chimpanzees

Abstract

Chimpanzee (Pan troglodytes) males are well known for their frequent displays toward viewers who approach and stand in front of their cages. If the front of the chimpanzees' cage is vertical and is constructed of bars or chain link framed by steel, the display includes “pant‐hooting,” then lunging onto the cage's front, followed by a series of vigorous attempts to shake the entire structure. The display is intimidating and can include spitting and throwing of materials. Also, displays can incur substantial damage to the cage over time. By sloping the front of the cage toward the center of the cage, the display pattern is profoundly attenuated both in frequency and form. Additionally, it serves to make the males more tranquil. No adverse effects on their health and well‐being over a 2‐year period have been noted.