| This dissertation contains four chapters. In Chapter I, I compared songbird communities among 9-year old burned, 22-year old herbicide treated (with 2-4,D), and untreated sites. The most pronounced differences in songbird species composition, richness, and relative abundance were between sites with the most shrubs (untreated sites) and areas with the fewest shrubs (burns). Songbird diversity (H{dollar}spprime{dollar}) did not reflect these community differences, but species richness and relative abundance were lower in treated sites and species composition changed between untreated and treated sites to favor ground-nesting species.; In Chapter II I compared songbird species occupance among habitat patch types and patch sizes, and species distance to edges. Sixty-seven percent of the songbird species (n = 9) selected the tallest sagebrush stands. However, small remnant shrub patches ({dollar}<{dollar}1 ha) had fewer shrub-nesting species than 2-ha remnant or 4-ha unfragmented patches. An interior species, the green-tailed towhee, was absent from small remnant patches and an edge species, the savannah sparrow, only occurred in remnant patches where burns and tall shrubs were juxtaposed.; In Chapter III I examined seasonal occurrences of sage grouse in untreated, burned, and herbicide treated habitats to determine the impacts of these pre-existing treatments. Nest success was associated with 41% shrub cover and the two nests found in the herbicide treated area with 15% shrub cover were not successful. In winter, sage grouse moved about 7 km south of their summer range to steeper south facing slopes where taller shrubs were exposed above the snow. The concentration of prescribed burns and herbicide applications on similar sagebrush stands on a south facing slope reduced potential winter habitat within the summer range.; Chapter IV contains a summary of my results and management recommendations. |
