All animals, including humans, are selective about the food they eat, (i.e., they chose particular items for food from a suite of resources that are potentially available to them). Much is unknown about the cues and criteria that animals use to choose adequate diets. This is especially true among plant-eating primates with simple stomachs (e.g. howler monkeys), who must choose a diet that is not only adequate in energy, but that also has an adequate mix of nutrients and low levels of toxins and indigestible carbohydrates. Wild howlers eat from the leaves of particular trees but ignore those of other trees of the same species. This study aims to identify the factors that govern such intra-specific food choices. It is an initial step toward understanding factors that govern choices across many food species. Trees of the same species that are used and ignored will be compared for: 1) chemistry (nutrients, structural carbohydrates, and toxins), 2) location, shape and structure, 3) productivity, 4) abundance, and 6) danger of predation. An understanding of the criteria these primates use to choose adequate diets will contribute to a greater understanding of their ecological needs and of their complex behavioral adaptations to a forest environment.
