Welcome to the American Ornithological Society 2018 Annual Conference. We are pleased to have you join us at the lovely Hilton El Conquistador Resort in Tucson, AZ.
Grassland birds have declined more precipitously than most other guilds of birds in North America since the 1970s. Rangelands managed primarily for cattle production support most of the limited grassland bird habitat that remains, but grazing impacts on grassland birds are not well described for species breeding in shortgrass prairie. In 2013, we initiated a grazing experiment at the Central Plains Experimental Range (CPER) in northeastern Colorado's shortgrass steppe to examine the effects of grazing on a variety of ecosystem services. Specifically, our objective was to evaluate how season-long grazing compared to adaptive rotational grazing, in the context of habitat and weather characteristics, affected breeding songbird abundance. We collected point count data (2013–2017) and used Bayesian N-mixture models to assess how grazing treatment, topography, soils, vegetation and weather affect the abundance of McCown's longspur, grasshopper sparrow and lark bunting. From some of our results, McCown's longspurs remained restricted to higher elevation sites with fine-textured soils on the CPER, even though portions of the CPER were grazed heavily to increase available habitat for this species. Grasshopper sparrows responded positively to a lack of grazing (rest) across the site and were more abundant in areas with taller vegetation and saline soils. In contrast, lark bunting abundance was significantly lower in areas with saline soils, and their abundance appeared driven by precipitation conditions rather than grazing treatment. These species-specific responses illustrate how teasing apart the influence of grazing practices and abiotic/biotic environmental conditions is critical to effective conservation for grassland birds.
