A note on the effect of auditory stimulation on the behaviour and welfare of zoo-housed gorillas

Abstract

Auditory stimulation has long been employed as a form of therapy for humans and animals housed in institutions. Its effect on one of our closest-living relatives, the gorilla, however, is largely unknown. This study explored the effect of auditory stimulation on the behaviour and welfare of six gorillas housed in Belfast Zoo. All animals were exposed to three conditions of auditory stimulation: a control (no auditory stimulation), an ecologically relevant condition (rainforest sounds) and an ecologically non-relevant condition (classical music). The gorillas’ behaviour was recorded in each condition using a scan-sampling technique. There was no significant effect of the auditory environment on the gorillas’ behaviour, although animals tended to show more behaviours suggestive of relaxation (i.e. resting, sitting) and fewer behaviours typically associated with stress (i.e. aggression, abnormal behaviour) during the ecologically relevant, and, in particular, the non-relevant, conditions than the control. Overall, findings suggest that certain types of auditory stimulation may hold some merit as a method of enrichment for zoo-housed gorillas, although more long-term work with a larger number of animals is needed before firm conclusions can be drawn.