PSU McNair Scholars Online Journal

Article Title

Effects of Environmental Enrichment and Natural Substrates on Increasing Species‐Specific Behavior of Captive Northern White‐Cheeked Gibbons (Nomascus leucogenys leucogenys)


Suboptimal housing conditions in zoos can cause animals to develop negative behaviors associated with excessive stress levels. Environmental enrichment and the use of natural substrates can decrease stereotypy and increase species-specific behaviors of captive animals (Gibbons et al, 1994). This study observed two pairs of gibbons (Nomascus leucogenys leucogenys) at the Oregon Zoo for 40 hours from July 5th through August 7th in order to analyze the effect that increased environmental enrichment and natural substrates had on the behavior of captive white-cheeked gibbons. One of the gibbon pairs (Phyllis and Duffy) had been housed in the new Red Ape Reserve for 10 months prior to this study. The experimental pair of gibbons (Nancy and Gunther) had access to the outdoor portion of the exhibit for two hours every morning beginning ten days prior to the start observations. The behaviors of the two pairs of gibbons were compared with the intention of determining the extent to which access to a larger, more natural environment with improved enrichment strategies promoted the species-specific behaviors of arboreality and brachiation. Activity levels were also analyzed to determine the extent to which the enrichment techniques have affected the cognitive health of the subjects. After all observation hours were completed, it was determined that within the experimental group, instances of brachiation, arboreality and activity levels increased significantly and the amount of time the subjects spent on or close to the ground decreased throughout the course of this study. It was concluded that access to natural substrates and increased environmental enrichment did increase species-specific behaviors of the captive white-cheeked gibbons at the Oregon Zoo.

Faculty Mentor: Dr. Deborah Duffield