Jones, Holly P.
M.S. (Master of Science)
Department of Biological Sciences
Grazing from native herbivores such as bison (Bison bison), in combination with prescribed fire, are applied to tallgrass prairies by managers to recreate important disturbance patterns in this ecosystem. Bird communities may be indirectly impacted by these disturbances through their direct impact on plants that provides critical breeding habitat for grassland birds. The objectives of this research are to determine the impacts that bison and prescribed fire have on grassland breeding birds in two tallgrass prairie preserves, Kankakee Sands and Nachusa Grasslands. Birds, vegetation structure, and bison activity were surveyed systematically at these two preserves in 2020 and 2021. Prescribed fire histories were derived from management records at both preserves. We used multivariate analyses to examine the differences in bird community composition between categorical disturbance types, survey year, and preserve location. Additionally, bird richness and focal grassland obligate species abundances were analyzed using generalized linear mixed models to determine the impact of disturbance, management, and vegetation variables. Though there was considerable overlap in bird community composition,categorical disturbance type impacted composition more than survey year or preserve location. Bird species richness was highest within management units that were unburned, regardless of bison presence, in comparison to burned units without bison. Vegetation structure had the largest impact on grassland obligate bird abundances, with grazing and fire disturbances having larger impacts than restoration planting age and spatiotemporal factors. We found that pyric herbivory impacted two grassland obligate species, Dickcissels (Spiza Americana) and Henslow’s Sparrows (Centronyx henslowii), that showed varying abundances when bison and fire interacted. These results highlight the importance of applying varying levels of grazing and fire disturbance in order to provide variable vegetation structure to accommodate the life history preferences of different grassland bird species.
Del Valle, Antonio, "Grassland Bird Responses to Bison and Prescribed Fire Disturbances at Nachusa Grasslands and Kankakee Sands" (2022). Graduate Research Theses & Dissertations. 6972.
Northern Illinois University
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