Feeding Ecology of Colombian wooly Monkeys

Primates have behavioural, social and morphological strategies that allow them to maximize the intake of nutrients from the resources they eat. Colombian woolly monkeys (Lagothrix lagotricha lugens), one of the largest Americas primate species, feed mainly on fruits, yet it is not well understood why they also eat a high percentage of arthropods instead of eating leaves like closely related Atelid species. In an 11 month study, we investigated the foraging strategies of this endemic monkey and assessed how resource availability affects dietary selection. Using behavioural, phenological, arthropod sampling and metabarcoding methods, we recorded foraging time, forest productivity and arthropod availability in the forest, as well as consumed. Scat samples and capturing canopy substrates (i.e. moss, bromeliads, aerial insects) were sufficient for assigning arthropod taxonomy. The most important resource in the diet were fruits (54%), followed by arthropods (28%). Resource availability predicted feeding time for arthropods but not for fruits. Further, there is a positive relationship between the feeding time of fruits and arthropods, perhaps eating both resources during the same periods might work as an optimal strategy to maximize nutrient intake. Woolly monkeys preferred and avoided some fruit and arthropod items available in their home range, choosing a wide variety of arthropods, being geometrid moths (Lepidoptera) the most important and consistent insect over time. We found no differences in the type of arthropods adults and juveniles eat, but adults invested more time foraging for this resource especially in moss. Although Colombian woolly monkeys are generalist foragers, we were able to show that they do not select their food items randomly or opportunistically.