The cranial morphology of large captive versus wild felids (918.11)

Most captive members of the genus Panthera are fed a nutritionally supplemented diet consisting almost entirely of ground meat. While the Association of Zoos and Aquariums discusses (but comes short of recommending) the supplementation of this diet with more complete carcass elements, the fact remains that large captive felids are fed diets that require substantially less masticatory effort than those of their wild counterparts. The osteological effects of this dietary difference have not been fully evaluated. We compared 3D geometric morphometric landmarks on a population of captive and wild lions and tigers. Though the first principal component (21.3% of the variation) separates the two species, the second principal component is driven not by the sex differences in these highly dimorphic species, but rather by their captivity status. In fact, captivity status drives nearly twice as much of the morphological variation as sexual dimorphism (15.6% vs. 8.0% for PC1 vs. PC2). If a causal relationship can be seen between mechanical diet and morphology, curators and nutritionists who oversee the diets of captive carnivores should consider modifying these diets to account for not only nutritional but also mechanical value as well.