Dr. Fuller’s research efforts focused on identifying factors affecting variation in mammal density and distribution. Whether a species is recognized as endangered, a nuisance, or harvestable, knowledge of its natural history and population ecology is essential in order to predict or responsibly manage population change. In order to better understand the mechanisms of this change, Dr. Fuller and his students captured, marked, and monitored a variety of carnivores, ungulates, and smaller herbivores to document their movements, habitat use, food habits, survival, reproduction, social behavior, and density, then synthesize results from their own and other studies. They surveyed populations through direct and indirect means (e.g., scats, tracks, calls, cameras) to assessed distribution and relative abundance, and also collaborated with colleagues to investigate roles of disease, genetics, nutrition, morphology, and human activities in population regulation and species conservation.