Impacts of ecological competition are reduced when organisms play different roles in their environment. More individuals can survive on varied but finite sets of resources when organisms eat different kinds of prey, live in different places, or are active at different times. Species within an assemblage of small fossorial snakes have ecologies that vary mostly by diet. Different species eat very different things. Species live in different habitats on sand ridges, but the differences are less dramatic than in diet. Disparity in resource use typically varies the most according to species, so that individuals of the same species are more similar to each other than they are to individuals of other species. However, variation exists in resource use within species over time and space. Wide variation exists in dietary resource use in four well-sampled species of comb-eared skinks. However, where species occur at the same study site there are clear distinctions in resource use between species despite the wide variation in diets observed between individuals of the same species. Additionally, strict ecological distances in diet between species are maintained during five censuses that were conducted over a 16-year period. These results illustrate the basic ecological principals of fundamental and realized niches. Here, individuals ate many different food items and species have the potential to overlap in diet but that overlap is reduced because of realized ecological boundaries between species within a single place and time, which result in decreased competition for resources. / text