Primate nutritional ecology: The role of food selection, energy intake, and nutrient balancing in Mexican black howler monkey (Alouatta pigra) foraging strategies

Studying primate nutritional ecology is critical for addressing questions related to individual and group-based decision making, feeding ecology, life history, and reproductive success. However, understanding food selection is a complex task, and it requires integrating information on physiology, behavior, and the ecological and social environments in which the animals live. In this dissertation, I examined the nutritional ecology of Mexican black howler monkeys (Alouatta pigra), an endangered nonhuman primate species characterized by a high intraspecific variability in time spent feeding on leaves, fruits, flowers, and other items (such as bark and stems) across seasons and study sites. Howler monkeys are considered the most folivorous New World primates, with leaves accounting for up to 100 % of feeding time during certain months. Given assumptions regarding the challenges faced by foragers exploiting difficult to digest or high fiber foods that also may contain plant secondary compounds, howlers are considered energy-limited. While howler monkeys do consume a leaf-heavy diet during certain seasons of the year, and possess certain anatomical and physiological traits such as a capacious colon where fermentation occurs, a relatively long food transit time for their body mass, and molars with high shearin