The continued fragmentation of natural environments across the continent has raised concern about the ability of sensitive species and ecological communities to persist into the future. To explore the patterns and processes of fragmentation in an arid setting, the vertebrate species present on habitat fragments of various sizes were analyzed in the Sonoran Desert. Species densities, vegetation parameters, and landscape variables were recorded. Strong vegetation changes were correlated with fragment age. Vegetation changes on the fragments included increased grass cover with decreased shrub cover. These changes in vegetation parameters corresponded closely with decreases in abundance of several species that were commonly found on control sites.