Route-tracing in captive Carnivora: is natural foraging niche a risk factor?

Many species from the order Carnivora are charismatic, so popular in zoos. Some of these species fare well in captivity, living long, healthy lives, breeding readily, with few or no behavioural problems. However, others do not adjust as well, with signs of compromised welfare such as elevated infant mortality rates, and prevalent repetitive behaviours such as route-tracing. One long-standing hypothesis for welfare problems in Carnivorans is that it reflects restriction of hunting behaviour. Support for this hypothesis includes that route-tracing is usually most intense immediately prior to feeding; compared with other mammalian orders, more prevalent in mainly carnivorous Carnivora; and that Carnivorans with long chase distances in the wild may spend the most time route-tracing in captivity. Using phylogenetic comparative methods (PGLS) our study further explores relationships between the diverse foraging niches occupied by these species, and their typical welfare. We analysed data on route-tracing and other abnormal repetitive behaviours from ~2,300 individuals across 56 Carnivora species. As a second welfare indicator, we also analysed infant mortality (IM) rates from ~24,500 births in these species in zoos. Next, we investigated the predictive power of aspects of foraging niche on captive welfare: dietary classification, reliance on hunting, hunting strategy, prey selectivity and chase distance. No aspect of foraging niche significantly predicted captive welfare. For instance, species with primarily meat-based diets, and thus reliant on hunting, did not route-trace more or have higher IM than omnivorous or herbivorous species (dietary classification: PGLS F2, 24=0.69, P=0.51, λ=0.98; F2,51=0.05, P=0.95, λ=0); and within predatory species, chase distance no longer predicted route-tracing (PGLS F1, 6=0.16, P=0.71, λ=0). These results therefore indicate that other aspects of carnivore biology have more influence on their welfare in captivity. Implications of the current study’s findings for captive carnivore welfare, will be discussed.