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

Olfactory stimulation has been shown to influence the behaviour of a wide variety of species and is now considered a useful form of environmental enrichment for many captive animals. To date, the effect of odour introduction on the behaviour of primates has been subject to little attention. This study thus investigated the behaviour of six zoo-housed western lowland gorillas in response to five odours (no odour [control], orange, vanilla, almond, peppermint) introduced individually on cloths into the animals’ exhibit for a period of 5 days per stimulus. The gorillas’ behaviour was recorded in each condition using a scan-sampling technique. Analysis showed that the gorillas sniffed the odour-impregnated cloths slightly (although not significantly) more frequently than the control cloths. There was no significant effect of olfactory stimulation on the gorillas’ general behaviour (P > 0.05 for all behaviours). Overall, findings suggest that olfactory stimulation in the form of odour-impregnated cloths has little effect on the behaviour of captive gorillas. This raises questions over the value of olfactory stimulation as a useful method of environmental enrichment for this species. Further research using different odours, methods of olfactory presentation, and larger numbers of animals is required, however, before firm conclusions regarding the value of olfactory stimulation for the great apes can be reached.