by Jeannine Cason Rodgers, enrichment, behavior and training specialist, and Dr. Christopher Cheleuitte-Nieves, senior clinical veterinarian, the Memorial Sloan Kettering Cancer Center and Weill Cornell Medicine; and Eme Chan, student at Cornell University College of Veterinary Medicine at time of study
Nonhuman primates housed in indoor laboratory environments are generally exposed to blank walls. This environment is not ideal for species whose primary sensory modality is visual. The aim of this study, which was funded by an AWI Refinement Research Award, was to assess the potential welfare benefits of providing a passive natural audio-visual stimulus to macaques.
Four long-tailed macaques were exposed to videos depicting scenes and sounds of natural landscapes projected onto the walls of their rooms. Urine cortisol:creatinine ratio levels—an indicator of stress—were gathered weekly, and behavior was scored from video recordings before, during, and after removal of the enrichment (four weeks in each condition).
Urine cortisol:creatinine ratios trended upward during visual enrichment and fell back to baseline levels after removal of enrichment; this trend may indicate a normal response to novelty. Behavioral analyses showed a decrease in stereotypies (abnormal, repetitive behaviors), such as rocking or pacing, during the study. Specifically, there was a trend toward a decrease in stereotypies when visual enrichment was present, and a further significant decrease after its removal. Positive behaviors increased during visual enrichment and decreased with its removal; these included allogrooming, cuddling, locomoting, observing (mirror), playing, and resting.
This study has provided preliminary evidence that projection of natural audio-visual stimuli as a form of environmental enrichment holds the potential to decrease stereotypies among indoor laboratory macaques.