Effects of Cattle Grazing on Grassland Bird Assemblages in South Texas Grasslands

Abstract

Many assemblages of birds have declined globally in the past several decades, with grassland bird species experiencing the most substantial declines. One of the leading hypotheses that explains this decline is the conversion of native grasslands to agriculture and ranching landscapes. Using point count data from 2015 to 2019, my goal was to perform a before-after-control-impact (BACI) assessment to determine the response of local grassland bird assemblages to various grazing regimes in south Texas. Continuous grazing treatments appeared to foster grassland bird richness, though Brown-headed Cowbird, Dickcissel, Grasshopper Sparrow, Northern Bobwhite, and Scissor-tailed Flycatcher densities were not impacted by grazing treatment. Eastern Meadowlark densities were impacted by grazing treatment, with a rotational moderate regime supporting the highest density. Both moderately and highly stocked rotational regimes may be beneficial for Eastern Meadowlarks, though lower cattle densities appeared to be most favorable. I recommend that ranchers in Texas implement rotational grazing systems as opposed to continuous systems in an effort to support Eastern Meadowlark density and foster grassland bird conservation.