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Exotic wildlife can have negative direct and indirect impacts on communities of native wildlife.� Exotic species may directly compete with native wildlife for resources or indirectly alter structure and quality of habitat for native species.� These direct and indirect effects would be most apparent in areas of high community overlap or use where the potential for interspecific interactions is greatest.� In arid regions, water is limiting and locations with water are likely areas of communal aggregation that may become flash points for interspecific interactions.� Our objective was to determine if exotic horses negatively influenced the community of native wildlife. �More specifically, we compared species richness and diversity of wildlife communities at water sources with and without feral horses (Equus caballus) in the Great Basin Desert, Utah.� We predicted that exotic horses would negatively influence species richness and diversity of native communities that access limiting sources of water. �We used infrared-triggered cameras to detect mammalian and avian species at 32 water sources. �We obtained 67,458 photographs of mammals (comprised of 16 species) and 34,038 photographs of birds (comprised of 60 species). �Species richness and diversity were greater�nearly double�at water sources where horses were absent than at water sources where horses were present.� There were no differences among water sources in landscape juxtaposition or surrounding habitats beyond the very local scale suggesting the differences are likely due to the presence of feral horses.� Water sources and the immediate surroundings that were used by horses were typically degraded and denuded of natural vegetation (due to trampling).� Our results indicate that exotic horses may exclude native species from access to a limited resource.