Sample-size effects on diet analysis from scats of jaguars and pumas

The Neotropics support more species of terrestrial vertebrate than any of the other seven biogeographic realms, including ~1,300 mammals and ~2,600 reptiles (Ash et al. 2005, Loyola et al. 2009). These provide a rich base of potential prey for large neotropical predators. Single rainforest locations have yielded as many as 24 different taxa in the diet of the jaguar, Panthera onca Linnaeus 1758, and 20 in the diet of puma, Puma concolor Linnaeus 1771 (Garla et al. 2001, Leite and Galvão 2002, Moreno 2006). Published diets deduced from the scats of top predators rarely acknowledge the taxonomic richness of potential prey in the area when evaluating whether the sample size can adequately represent the true dietary richness and breadth. Diet studies consequently risk underestimating plasticity in feeding ecology, and wildlife managers may fail to distinguish predator species that have the potential to adapt to diminishing prey diversity from those that do not. Jaguars and pumas co-exist in increasingly fragmented and human-dominated landscapes where they must compete with humans not only for habitat but also for prey (Foster et al. in press, Leite and Galvão 2002). Understanding dietary flexibility of such large felids will allow us to better predict the impact of changes in prey availability on their long-term persistence, and on patterns of co-existence (Foster et al. in press). Here we investigate the influence of scat sample size on: (1) the number of taxa detected in jaguar and puma diets, using data from 25 published studies; and (2) the precision of estimates of the relative occurrence of common prey species in jaguar and puma diets, by sub-sampling from our own large datasets of genotyped scats (Foster et al. in press). Relative occurrence is defined as {number of prey items belonging to species X}/{total number of prey items} x 100. Species are considered common at ?5% occurrence in the diet