Introduction

If animals are to be kept in the best possible state for exhibition, propagation and eventual release into the wild, what are the consequences of keeping small numbers of individuals in less complex environments? Since Hediger stressed the importance of studying the reactions of animals to their confinement as early as 1934 (Meyer-Holzapfel, 1968), much research has focussed on the behaviour of vertebrates in captivity. Much is known about the conduct of captive primates and carnivores, but much less about other mammals, birds, reptiles and amphibians. The last 20 or so years have seen a substantial growth in the number of behavioural studies undertaken in zoos; some are basic research on ethology and behavioural ecology, but most are applied and designed to understand how captive environments influence behaviour (Hosey, 1997). However, interpreting the results of these studies, particularly those on the influence of the captive environment, can be difficult, because it is by no means clear what benchmark should be used for evaluating behaviours seen in captivity.