Stereotypies and suffering.

Stereotypies often develop in environments that independent evidence shows cause poor welfare. Thus the development od stereotypies indicates that well-being has probably been poor, with the animal motivated to show a behaviour pattern that it could not perform normally or to completion. The continued performance of stereotypies may also indicate current suffering. However, an individual or population's degree of stereotypy does not necessarily correspond to the degree to which its well-being or welfare is impaired. This would require individual differences in stereotypy level to be the product of motivational differences and nothing else. In fact, they are also likely to be influenced by an animal's tendency to respond to the eliciting aspects of its environment with active behaviour rather than in a more inactive way. Stereotypy levels are also likely to be influenced by the general propensity of the individual to develop inflexible behavioural routines. Furthermore, as a stereotypy develops and becomes more habit-like it may be performed in circumstances where well-being is not at stake. Thus when comparing animals, lower levels of stereotypy do not necessarily reflect better well-being. General rules about the levels of stereotypy that are deemed "acceptable" from a welfare point of view are of limited use in reducing animal suffering unless they take take these factors into account. There is a great need for more research into the developmental processes responsible for stereotypies.