Get reliable science

Trend analysis from the North American Breeding Bird Survey indicates that the Sprague's Pipit (Anthus spragueii) is experiencing a severe population decline (4.1% annually). This drastic population decline has led to the listing of the Sprague's Pipit as a candidate species under the Endangered Species Act in 2010. The Little Missouri National Grasslands in North Dakota are listed as an important breeding area for the Sprague's Pipit and other sensitive grassland birds. With a major reduction in fire frequency in this region, livestock grazing has increasingly played a larger role in the structuring of grassland communities. The timing and intensity of grazing by livestock influence vegetation structure, composition, primary productivity, and ultimately Sprague's Pipit occurrence and abundance. Our objectives were to evaluate effects of livestock grazing on vegetation structure and composition, grassland bird density, and grassland bird diversity and community composition. Sixty study sites (i.e., legal quarter-sections) were selected using random stratified sampling. Sites were surveyed twice during the summer of 2014 using a modified transect survey to evaluate grassland bird presence and abundance. To capture the vegetation structure at the time of the bird surveys, we also collected data on vegetation structure (e.g., VORs, maximum vegetation height, and litter depth) and biomass at each study site on or near the day of each bird survey. Sprague's Pipits also have been found to closely associate with native vegetation throughout their breeding range. To test this we sampled site plant communities using modified Whittaker plots to detect species richness and diversity as well as using ocular estimation to determine percent cover. Preliminary results show that livestock grazing does influence vegetation structure, thus affecting grassland breeding bird density and community composition. Our data also suggest that vegetation structure, and not composition, influences the occurrence of Sprague's Pipits.