Abstract
In an Upper Sonoran Grassland Community, three species of Pogonomyrmex ants coexist. Due to the similarity in their diets and the apparent limitation of food, coexistence is aided by the differential utilization of the available food, according to size and type. Interspecific differences in morphology, physiology and microhabitat nesting sites facilitate this division. Differences in morphology enable the foragers to handle and collect seeds of different size and, consequently, type. Differences in desiccation resistance enable the foragers to be active at different times and, consequently, incorporate different amounts of insect material into their diets. Differences in microhabitat nest sites offers the foragers different proportions of the desired food resource.