ENVIRONMENTAL ENRICHMENT - INCREASING THE BIOLOGICAL RELEVANCE OF CAPTIVE ENVIRONMENTS

Environmental enrichment is a vague concept referring to improvements to captive animal environments. Some authors have applied the term to an environmental treatment itself, without any concrete evidence that the treatment represented an improvement for the animals. Others have used the term when the main beneficiaries may have been people rather than their captive animals. The criteria used to assess enrichment hav e also varied according to animal use (e.g. laboratory, farm or zoo an imals). In this paper, environmental enrichment is defined as an impro vement in the biological functioning of captive animals resulting from modifications to their environment. Evidence of improved biological f unctioning could include increased lifetime reproductive success, incr eased inclusive fitness or a correlate of these such as improved healt h. However, specifying an appropriate endpoint is problematic, especia lly for domestic animals. Potential methods of achieving enrichment th at require further investigation include presenting food in ways that stimulate foraging behaviour and dividing enclosures into different fu nctional areas. The quality of the external environment within the ani mals' sensory range also deserves greater attention. A common shortcom ing of attempts at environmental enrichment is the provision of toys, music or other stimuli having little functional relevance to the anima ls. Failure to consider the effects of developmental factors and previ ous experience can also produce poor results. Environmental enrichment is constrained by financial costs and time demands on caretakers, and providing live prey to enrich the environment of predators raises eth ical concerns. Future research on environmental enrichment would benef it from improved knowledge of the functions of behaviour performed in captivity and more rigorous experimental design.