Documenting relationships between small mammals, ground-nesting passerine birds, and grazing systems on private rangelands in the Nebraska sandhills

Introduction Biologists lack a great deal of information about wildlife in the Nebraska Sandhills, especially on private rangelands. For example, there is little knowledge about the small mammals of the area and their role in the ecosystem in which they live. Because only three percent of Nebraska is public land (Schneider et. al 2005), private land management is, by default, critical to the biodiversity of grasslands in Nebraska. Thus research on private property in the state can be very useful to planning. The Nebraska Sandhills are geographically unique and biologically diverse. The region is the largest grass-stabilized sand dune area in the Western Hemisphere, stretching 265 miles and covering approximately 19,300 square miles (Bleed and Flowerday 1989). The rolling sand dunes were formed by blowing sand and are currently stabilized by grass. These dunes typically have dry uplands and wet inter-dunal lowlands. Biodiversity is also high in the Sandhills. Terrestrial vertebrates include 55 species of mammals (Freeman 1989b), 27 species of amphibians and reptiles (Freeman 1989a), and 137 species of birds (Labedz 1989). There is also a diverse plant community of approximately 720 species (Kaul 1989). A small mammal community can have several effects on the ecological community of an area. For example, small mammals can serve as a prey species for first-level carnivores (Greenwood 1982) while also acting as nest predators of ground-nesting passerine birds (Maxson and Oring 1978; Pietz and Granfors 2000). Their place in the food web makes small mammals an important component of the Sandhills ecosystem. There were two objectives for this study. The first was to inventory the small mammal community in eastern Cherry County, located near the center of the Sandhills region of the state. The second objective was to document any relationships between small mammals, ground-nesting passerines and their nests, and vegetation composition of sampled pastures. Methods Field Methods I conducted this small mammal study on six private ranches in the Nebraska Sandhills, in eastern Cherry County (Figure 1). I sampled small mammals on three grazing systems in conjunction with a grassland songbird study (S. Finkbeiner, UNL, unpublished data). There were two replicate pastures assigned within each grazing treatment (long-, medium-, and short-duration grazing, Table 1). Long-duration pastures were grazed continuously throughout the grazing season. Medium-duration pastures were managed to rotate grazing pressure through five or more paddocks in each pasture. Short-duration pastures contained an average of 40 paddocks, of which grazing pressure …