Claxton, A. M. 2011. The potential of the human-animal relationship as an environmental enrichment for the welfare of zoo-housed animals. Applied Animal Behaviour Science 133(1), 1-10.

Environmental enrichment strategies are used to improve both the physiological and psychological welfare of captive animals, which can be achieved by increasing the expression of natural behaviour and decreasing abnormal behaviours. Examples of successful environmental enrichment include the improvement of enclosure design, and the provision of feeding devices, novel objects, appropriate social groupings and other sensory stimuli. However, a key factor contributing to how a captive animal interacts with its environment is its relationship with humans. Firstly, this paper focuses upon the extent to which an animal's fear of humans may affect its overall behaviour, and the consequences of the subsequent human–animal relationship (HAR). Widely studied in farmed animals, the majority of data collected in the area of the HAR in exotic species largely focuses on primates and it is therefore also considered that further investigation is required to understand the impact of the HAR, particularly on the behaviour and welfare of a broader range of zoo-housed species – whose routine involves daily contact with both familiar and unfamiliar people. Research concerning the HAR is put into context of the field of environmental enrichment by discussing evidence which suggests that human contact meets some of the criteria that traditional methods of environmental enrichment aim to satisfy. A model has been developed to test the HAR in the zoo environment and, in doing so, predictions can be reliably made about how animals may react to humans. Here, the model has been further adapted to include predictions about the extent to which the HAR may affect an animal's daily behaviour budget and its reactions to other aspects of the zoo environment. It is also suggested that comparisons can be made directly between an animal's response to humans and to traditional enrichment methods in an attempt to determine if the HAR itself has any use as a form of environmental enrichment. Future research in this field has important implications for the management of captive zoo-housed animals through the design of appropriate husbandry procedures to improve captive animal behaviour on a species-specific basis and, in turn, for satisfying the zoo mission as a whole.