Environmental enrichment means making additions to a captive enclosure or husbandry regime, typically with a view to improving it; these additions could include new substrates (e.g. natural flooring), items (e.g. ‘toys’ or novel objects), shelters, scatter feeding, and opportunities to perform natural behaviour. To people interested in improving animal welfare, a good enrichment is one that reduces signs of stress or unwanted activities like stereotypic behaviour, and also that the animal itself values (i.e. the animal finds the enrichment rewarding to interact with). In my presentation, I will illustrate why enrichment is important, and what additional (perhaps unexpected) benefits it might have for zoo animals.
First I will discuss what captivity ‘means’ to a wild animal. Captive animals often live longer than their counterparts in the wild, because they are protected from predation, treated when they have diseases or are injured, and never experience drought or starvation. However, captivity brings with it many potential sources of stress: these include the enforced proximity of cagemates, and in badly designed zoos, the enforced proximity of natural predators; close contact with humans (which animals may perceive as predators); and the impossibility of performing natural behaviours like burrowing, hunting or flying which may be ‘behavioural needs’ (activities that are intrinsically rewarding to perform). Whether the positive aspects of captivity outweigh the negative aspects will vary according to the zoo, the type of enclosure, and the species itself. The impact of captivity also varies according to whether the animal was imported from the wild, and instead born and raised in a zoo enclosure.
When conditions are inappropriate, what do we see? Stereotypic behaviours are performed by tens of thousands, possibly even hundreds of thousands, of zoo animals around the world. These repetitive actions include pacing, head-swaying, or even repeated regurgitation-and-reingestion, and they resemble the abnormal activities of humans with psychological problems like autism or schizophrenia. These, and other negative effects of captivity (for example, poor breeding success, high infant death rates, and sometimes poor rates of adult survival) are both ethical problems because they indicate potential animal suffering, and also practical, management problems that interfere with the goals and ideals of good zoos. I will show how environmental enrichment in zoos can help reduce, or even abolish, these problems. I will give specific examples of successes and failures, as well as an overview of how well they typically work.
Finally, using scientific studies on research animals (e.g. laboratory rats, mice and zebra finches) I will then illustrate some other, additional benefits of environmental enrichment which we should also expect to see in captive wild animals. These include: better abilities to cope with stressors outside the home cage (e.g. being handled or transported); better resistance to some illnesses; making it easier for human carers to detect disease in its early stages; better brain function and improved cognitive abilities; and even greater attractiveness as potential mates to animals of the opposite sex. All these benefits are exciting areas for future investigation in the zoo world, and emphasize yet again how crucial it is to utilize successful environmental enrichment.