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Aspects of the population biology and community ecology of three sympatric species of snakes (Coluber constrictor, Masticophis taeniatus, and Pituophis melanoleucus) using communal dens in a Great Basin cold desert shrub habitat were studied in northern Utah between 1969 and 1973. Food habits analysis and telemetric tracking of snakes in the field allowed quantification of the food and place dimensions of the ecological niche of each species. We also report on thermal preferences, temporal overlap at hibernacula, annual body weight changes, and survivorship of these species. Species abundance distributions and species diversity in 10 North American snake communities are surveyed. The species were separated strongly by food habits. Major prey taken were insects (Coluber), lizards (Masticophis), and mammals (Pituophis). Coluber had the narrowest food niche, Pituophis was intermediate, and Masticophis had the broadest niche. In summer, Masticophis had the broadest place niche and differed from Coluber and Pituophis, which were underground most often. All three paired species comparisons showed the average overall niche overlap values were 0.79 (place) and 0.19 (food). The trophic dimension is more important in resource partitioning than is the spatial dimension for snakes in this community. Complementarity between these two niche dimensions exists. Snakes, as a group, had lower mean activity temperatures than lizards at our study locality. Thermal preferences underground (26-27 C) were very similar among the snakes. Pituophis had a lower mean activity temperature (28 C) than Coluber and Masticophis (31-32 C …