Body mass and skull measurements in four jaguar populations and observations on their prey base

Abstract

Body mass and nine skull measurements of two floodplain (Pantanal and Llanos) and two forest (Amazon and Central America) jaguar (Panthera onca) populations, were analyzed to compare them, relate their morphometric dimensions to preybase and latitude, and examine the relationship with their subspecies status. Analyzing data from males and females separately, jaguar at all sites differed significantly for most variables studied, with the exception of rostral breadth, maxillary teeth row length, and pterygoid fossa breadth for both sexes, and postorbital breadth for females, which were either not or only weakly significant. Individuals from the floodplain populations were consistently larger in almost all parameters than the samples from the forest sites. The difference is independent of the subspecific status. Comparisons among the biomass values of prey taken at each site were also consistently higher for floodplain populations. Jaguar skull size and body mass seem to be more related to biomass of prey taken than to latitudinal location. The differences found in these four populations and the high number of Central American subspecies suggest that a revision of subspecies validity is needed. The reduction in the subspecies number is not only important from a taxonomic point of view but also from an ecological and conservationist one. The increase of our understanding of the phylogenetic heritage and morphological and ecological variation within the species is a priority for conservation.