Potential determinants of the abundance of woolly monkeys in neotropical forests

Abstract

The most important proxy of species extinction is rarity, which is usually associated with low population abundance. Woolly monkeys are severely threat- ened and few studies have compared the abundance of woolly monkeys across the Neotropics. In this study, I analyze the abundance of woolly monkeys (Lagothrix spp.) and I postulate the most likely ecological factors determining the variation in their biomass. I compiled information from ca. 50 Neotropical sites, including estimâtes of fruit production, climatic parameters, plant composition, and information on primate assemblages. I used simple regression models at three scales: Neotropics, within their geographic range, and where they occur. At the largest spatial scale, several variables that are known to vary with latitude were highly associated with the abundance of woolly monkeys (e.g., rainfall, number of dry months, and plant species richness). However, their explanatory power decreased at smaller scales, suggesting strong biogeographic effects determining their distribution. Overall, I found that the most important variables explaining the abundance of woolly monkeys across scales were fruit production and the abundance of some key resources (i.e., Inga spp.). As fruit production seems to be associated with high soil fertility near the Andean mountains, this region should be a priority for the conservation of this species.