Abnormal repetitive route-tracing in captive Carnivora: is natural foraging niche a risk factor?

In zoological collections, species from the diverse order Carnivora are charismatic and popular. Some of these species typically fare well in captivity, living long, healthy lives, breeding readily, and showing few or no behavioural problems. However, others do not adjust as well, with signs of compromised welfare such as poor reproduction, and abnormal repetitive route-tracing (e.g. pacing) being prevalent. One long-standing hypothesis is that restricting hunting behaviour compromises carnivore well-being. Support for this hypothesis includes that route-tracing is usually at its most intense immediately prior to feeding; that route-tracing is more prevalent in Carnivora than other mammalian orders; and that previous work suggested that species with long chase distances in the wild spend the most time route-tracing in captivity. Using phylogenetic comparative methods this study further explores relationships between foraging niche and carnivore welfare. We updated an extensive database of abnormal behaviours and infant mortality rates in captive Carnivora, to now include data on route-tracing (the most common abnormal behaviour in these animals) and other repetitive behaviours (e.g. repetitive oral behaviours like bar-biting) in 2,337 individuals from 57 species held in zoos worldwide. Next, we investigated the predictive power of various aspects of foraging niche on captive welfare, including: species-typical foraging methods and hunting style, mode of locomotion, top speeds attained and gaits used during chase, among others. Our findings are important at two levels. By understanding the evolutionary basis of species variation in captive carnivore welfare, the welfare of thousands of individuals may be improved. For example, practical recommendations can be made to tailor enrichment and husbandry design to better support performance of highly motivated behaviour. In addition, there are long-term fundamental gains to be made from this study, as findings should be integrated into zoological collection planning and management: all highly topical issues.