Abstract. Stereotypies are repetitive, invariant behaviour patterns with no obvious goal or function. They seem to be restricted to captive animals, mentally ill or handicapped humans, and subjects given stimulant drugs. In this respect they are abnormal, although possibly the product of normal behavioural processes. Stereotypies are often associated with past or present sub-optimal aspects of the environment, and have been used as a welfare indicator. It has been hypothesized that stereotypies have beneficial consequences which reinforce their performance, although other means, such as positive feedback, may equally explain their persistence. Empirical evidence links them with lowered awareness of external events, and reduced arousal and distress. However, as most of this evidence is correlational it remains uncertain that the stereotypies are themselves the cause of coping. Furthermore, they are heterogeneous in source of origin, proximate causation and physical characteristics, and they change over time in important respects, becoming more readily elicited by a wider range of circumstances. Therefore the properties of one stereotypy are not necessarily those of another.

This paper summarises recent findings on the causation of stereotypic behaviours and other abnormal repetitive behaviours (ARBs) in captive animals: primarily motivational frustration and/or brain dysfunction, with possible contributory roles also being played by habit-formation and 'coping' effects. We then review the extent to which ARBs occur in zoos and similar, estimating that at least 10 000 captive wild animals are affected worldwide. We argue for 'zero tolerance' of such ARBs, because stress and poor welfare raise ethical issues, while abnormal behavioural phenotypes and possibilities of impaired brain development challenge both the indirect (e.g. educational) and the direct, intrinsic conservation value of affected animals. We then consider five potential means by which ARBs may be tackled: genetic selection; pharmacological treatment; the reinforcement of alternative behaviours; punishment; and environmental enrichment. All except punishment have potentially useful roles to play, but enrichment is the preferred approach: it is most likely to tackle the problems underlying stereotypic behaviours, and thence to improve both welfare and behaviour with few unwanted side-effects. Nevertheless, in zoos, environmental enrichment to date has only had partial success, with no study managing to abolish ARBs in all its subjects-suggesting either that the enrichments currently being used are never quite optimal, or that by the time they are tackled, ARBs have become resistant to change. We suggest some ways in which the effectiveness of enrichments may be enhanced; propose that certain properties of ARBs may usefully help evaluate their likely 'treatability'; and emphasise that if improving welfare is more important than just reducing ARB, then additional measures are needed in order to first, reliably identify those individuals most at risk from poor welfare, and then, to fully evaluate the welfare impact of enrichments. This paper also emphasises, with examples, the enormous potential value of zoo-derived data for helping understand

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Understanding a species' behaviour in natural conditions can give insights into its development, responses and welfare in captivity. Here, we review research and pest control literatures on the free-living house mouse (Mus musculus), analysing its sensory world, developmental processes and behaviour to suggest how laboratory environments might affect mouse welfare, normalcy, test design, and behaviour. Mouse development from foetus to weaning is influenced by prenatal stress and nutrient levels, and post-natal litter size and other factors affecting maternal care, all with lasting effects on adult bodyweight, aggression, activity levels, stress responsiveness and masculinisation. These influences may well be important in the laboratory, for example unwittingly differing between facilities leading to site-differences in phenotype. Murine senses are dominated by olfactory, auditory and tactile cues. Their hearing extends into the ultrasonic, and vision, from mid-range wavelengths to the ultraviolet. In mouse facilities, behaviour and welfare may therefore also be affected by sensory stimuli unnoticed by humans. The physical and social environment and behaviour of wild mice differ greatly from those of laboratory mice. Dispersal age varies with resource-levels and social cues, and mice often either live alone or in family groups. Mice occupy territories/ranges measuring a few square meters to several square kilometers, and which allow running, climbing, and burrowing. Mice are often active during dawn/dusk, and spend their time patrolling their territories, investigating neighbours' odour cues, foraging, finding mates and rearing litters. The potential impact of these many differences and restrictions on laboratory mouse development, normalcy and welfare has only begun to be explored.

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