Geophagy in Wild Yellow-Tailed Woolly Monkeys (Lagothrix flavicauda) Is Brief and Rare

Abstract

Many primates intentionally consume earth. This geophagy has probable health benefits, such as mineral supplementation or gastrointestinal tract protection, and is likely to be an important behavior for a species’ ecology, health, diet, and conservation. We investigated geophagy in the Critically Endangered yellow-tailed woolly monkey (Lagothrix flavicauda). We collected observational data and camera trap records over 2 years at La Esperanza study site, northern Peru. Geophagy was rare, with 67 events recorded during the study. All age/sex classes engaged in geophagy, but adult males spent significantly less time consuming earth in situ than adult females did. Geophagy occurred predominantly during the dry season and was a solitary behavior. The forest floor is presumably a high-risk environment for these predominantly arboreal primates and our study animals employed various strategies to minimize predation risk. These included using a single route to access and leave geophagy sites, displaying increased vigilance behaviors before and during geophagy events, and minimizing the time spent on the forest floor (mean: 15 ± SD 9 s). They also maximized the benefits of being on the forest floor by removing earth to consume ex situ. These findings provide the first steps in the systemic approach required to understand the role geophagy plays in our study species, whose almost exclusive arboreality, coupled with the increased predation risk associated with terrestriality, suggests that geophagy confers an important benefit.