The Influence of Grazing Systems on Bird Species Richness and Density in the Nebraska Sandhills

Abstract

Grazing is the de facto method of habitat management used in much of the Nebraska Sandhills. Ranchers use a variety of grazing systems, and our goal was to evaluate the effects of systems on grassland birds. We estimated the species richness and density of grassland birds for three grazing systems used on private ranches: long, medium, and short duration grazing systems. We observed sixty species, and the grazing system with pastures utilizing long duration grazing periods had the highest estimates of species richness as well as the most heterogeneous habitat structure. Differences in species richness among systems were most pronounced in years of limited precipitation. Together, grasshopper sparrows (Ammodramus savannarum), western meadowlarks (Sturnella neglecta), and brown-headed cowbirds (Molothrus ater) accounted for 72% of our observations. We used a model comparison approach to determine the effects of habitat on the densities of six species. Densities of grasshopper sparrows and mourning doves showed effects of the grazing system. More species had higher densities in short duration, rotational systems than other grazing systems. However, species of grassland birds showed responses to a variety of cover types and habitat structures depending on life history needs. Regardless of the grazing system used, managers can use grazing and other tools such as prescribed burning to maintain habitat heterogeneity to support diverse bird communities.