Date of Award
Master of Science
Wildlife and Fisheries Science
Patrick D. Keyser
Rober D. Applegate, David A. Buehler, Bruce A Ralston
Grassland birds have declined more than any other guild of birds in North America, largely due to loss and degradation of native grasslands. The Conservation Reserve Program (CRP) has restored some native warm-season grasses (NWSG), but grassland birds continued to decline (-1.1% annually) partly due to the limited acreage converted (1% of southeastern US). Using NWSG in production settings provides profit incentive to landowners while reducing dependency on government programs. Studies examining these production practices and their effect on grassland birds east of the Great Plains are limited. During 2009 – 2010, I surveyed 102 NWSG fields in Kentucky and Tennessee being used for production purposes (control, biofuel, seed, hay, and pasture treatments) to assess bird use and vegetation characteristics. Landscape cover around each field (250, 500, and 1000 m) was digitized from aerial photography. Using analysis of variance (ANOVA), I compared bird (relative abundance, species diversity, and species richness) and vegetation (average height, litter depth, vertical cover, litter cover, and vegetation cover) metrics across the five treatments. Relative abundance for all species, species diversity, and species richness were all greater for seed production fields (P <0.05); other treatments did not differ. Field sparrows (Spizella pusilla) were less abundant (P <0.05) in biofuel than control, hay and graze treatments, whereas eastern meadowlarks (Sturnella magna) and dickcissels (Spiza americana) were more abundant in seed fields. Average vegetation height, vertical cover, percent litter, percent forbs and percent woody plants differed (P <0.05) among treatments. Using Program Mark, I modeled occupancy for field sparrow, red-winged blackbird (Agelaius phoeniceus), eastern meadowlark, and northern bobwhite (Colinus virginianus) using vegetation and landscape cover as covariates. Treatment was influential in field sparrow and eastern meadowlark models, but not those for red-winged blackbird and northern bobwhite. Occupancy for field sparrow and northern bobwhite were affected by woody cover (+), for red-winged blackbird by vegetation height (-), and for eastern meadowlark by litter depth (+) or percent NWSG (+). All four species were negatively affected by forest within 250-m. Use of NWSG in production could increase the amount of available habitat and thus, help conservation efforts for grassland birds.
West, Andrew Steven, "Avian Response to Production Stands of Native Warm-Season Grasses in the Mid-South. " Master's Thesis, University of Tennessee, 2011.