At first glance, the shortgrass steppe seems to offer little in the way of habitat for mammals. The expansive rolling plains, with little topographic relief or vegetative cover, provide minimal protection from predators or the harsh weather typical of the region. The short stature of the dominant native grasses prevents the development of any significant litter layer, and although snowfall can often be significant, too little accumulates to form the subnivean habitats that support small mammal populations in forests and more productive grasslands in winter. As a consequence, ecologists have typically considered the vertebrate fauna of the shortgrass steppe to be depauperate compared with other Great Plains grasslands, a hardy collection of generalists living in sparse populations. Although this characterization may generally be accurate, it has led mammalian ecologists to overlook the fauna of the shortgrass steppe in favor of that of other grasslands. It is precisely these circumstances, however, that suggest that a long-term approach may be necessary to understand the dynamics of mammal populations here. Relatively few such studies have been completed to date, but we can use the comparative and experimental results that are available to begin to determine what factors might be important. Here we review research on mammals in the shortgrass steppe, with the goal of identifying the general patterns and processes that contribute to them. Our review is roughly divided into four parts. We begin by describing the mammal communities and their broad habitat associations in shortgrass steppe environments. We then review the history of mammal research in the region to synthesize what these studies (many unpublished) have taught us about the most important determinants of the distribution and abundance of native species. Studies of mammal\ populations in the northern shortgrass steppe have spanned nearly 40 years, and we next describe some major patterns that have emerged from studies during this period. Much of this past research focused on the role of mammals in the structure and function of shortgrass steppe ecosystems, and we revisit this issue in some detail, with special emphasis on the important and sometimes controversial role of prairie dogs and other burrowing rodents. Finally, we end by considering how humans, and especially agriculture and its related activities, affect the diversity, abundance, and persistence of resident mammal populations.
Rodent Communities in Active and Inactive Colonies of Black-Tailed Prairie Dogs in Shortgrass Steppe
