Thesis (M.S.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Sept. 15, 2009). Thesis advisor: David A. Buehler. Vita. Includes bibliographical references.

For several decades, grassland bird populations have been facing consistent declines throughout North America with population declines >1.5% per year in the past 40 years in the eastern United States. If this current rate persists, the populations will be reduced to half their current size in less than 50 years. Multiple causes have been proposed to explain the decline of grassland birds, but loss of available habitat and declining habitat quality are recognized as key elements in the decline of this guild. The Champlain Valley has the potential to be an important area for the conservation of grassland birds due to large acreage of grassland habitat; however, management practices are not always compatible with grassland bird habitat requirements. Therefore, there is a need to focus conservation efforts in areas that will have the greatest probability of maintaining populations of grassland birds. This project was designed to identify priority areas for implementing conservation programs for grassland birds in the Champlain Valley of Vermont. Using ArcGis, I created detailed layers that included landscape level factors (forest, grassland, development and roads) and patch level factors (size, management and conservation) important in grassland bird habitat selection. Integrating the GIS dataset into a multicriteria decision analysis framework, I produced maps in which grassland patches were ranked on the basis of their quality for grassland birds. The Analytic Hierarchy Process was the decision rule used to identify priority conservation areas. The use of a hierarchical structure distributed the relative weights of different factors deemed important by grassland bird experts, allowing a greater number of criteria to be included while keeping the methodology manageable. These procedures resulted in a series of habitat quality maps that federal, state, and non-governmental land managers will be able to use as a baseline to focus conservation efforts on areas that will have the greatest probability of maintaining viable populations of grassland birds. The maps emphasize the protection of grassland patches larger than 5-10 ha that are 2 km away from roads with high traffic, and the selection of blocks of > 50 ha of protected or bird-friendly grassland habitat. The Analytic Hierarchy Process is a flexible method that can be applied to conservation decisions across a variety of ecosystems and species.

Thesis (Ph. D.)--University of California, Davis, 2005. / "June 2005"--Leaf 1. Degree granted in Ecology. Includes bibliographical references. Also available via the World Wide Web. (Restricted to UC campuses)

Thesis (M.S.)--Pennsylvania State University, 2008. / Mode of access: World Wide Web.

I investigated the relative effects of grassland cover and fragmentation per se, and the relative influence of landscape and local habitat characteristics on grasslands songbirds in the moist mixed-grass prairies of Manitoba. In 2013, 361 avian point counts were conducted across 47, 2.4-km radii landscapes in the southwest part of the province. I used an information-theoretic approach to rank and select models describing effects of landscape and local-scale habitat variables on grassland songbird abundance and occurrence. Overall, my results indicate that grassland amount, fragmentation and quality, and matrix composition had relatively small and variable effects on grassland songbird abundance and occurrence, but that abundance of obligate species when pooled showed a strong negative response to grassland fragmentation. While fragmentation through edge effects may contribute to obligate species declines, my results suggest that these factors alone are unlikely to explain ongoing declines of grassland birds in southwestern Manitoba. / October 2016

Master of Science / Division of Biology / David A. Haukos / Sericea lespedeza (Lespedeza cuneata) is an invasive forb that reduces native grass and forb abundance in tall-grass prairie by up to 92%. Controlling invasions is difficult because traditional land management tools used in the Flint Hills, broad spectrum herbicides, spring prescribed fire, and cattle grazing, are ineffective against sericea. Recent research has demonstrated, however, that mid- and late summer prescribed fire and spring fire with early season grazing by steers followed by late season grazing by sheep are effective at reducing sericea whole plant mass, number of seeds produced, and seed mass. Field results were from two separate experiments conducted in tall-grass prairie study sites in the Flint Hills. On a Geary County, Kansas, study site, the utility of 1) spring fire (control), 2) mid-summer fire, and 3) late summer fire on sericea control were compared. On a Woodson County, Kansas, study site, the utility of 1) spring fire with early season steer grazing followed by rest (control) and 2) spring fire with early season steer grazing and late season sheep grazing on sericea control were compared. At the same study sites, I measured responses by the native wildlife community to use of summer fire and sheep grazing, relative to their controls, to manage sericea lespedeza. Specifically, my objectives were to compare grassland songbird density, grassland songbird nest survival, and grassland butterfly species composition and density among treatments at both study sites. I also related patterns in the vegetation community of each treatment for each study site to respective patterns in grassland bird and butterfly communities. Within study sites, density, nest density, and nest success of grassland bird communities responded similarly to treatments and controls, with the exception that densities of Grasshopper Sparrows (Ammodramus savanarrum) were 3.4- and 2.2-fold greater in mid- and late summer fire plots than spring fire plots, respectively, in the Geary County study site. Species compositions of butterfly communities were similar across treatments within experiments, but grassland specialist species comprised only 8.6 and 1.2% of all butterfly observations in the Geary County and Woodson County experiments, respectively. Grassland specialist butterfly species may benefit from summer fire, as their nectar sources were more abundant in Summer Fire plots than Spring Fire plots. Overall, within each experiment, grassland bird and butterfly communities were similar across treatments, suggesting that treatments did not negatively affect grassland songbird and butterfly communities. I additionally demonstrated that Dickcissel (Spiza americana) nest sites contain a lower proportion of sericea than random points, the first evidence that the invasion is detrimental to grassland songbird species. Lacking control, the continued sericea invasion will out compete cumulatively more forb plants resulting in declining quality of grassland bird nesting habitat on the landscape. Controlling sericea lespedeza invasions will allow native forb species to increase in abundance and improve the condition of grasslands for native wildlife and livestock producers. Therefore, I advocate use of summer fire or spring fire with a combination of cattle and sheep grazing to control sericea lespedeza with the long-term goal of tall-grass prairie restoration.

There has been a critical decline in grassland bird populations due to habitat fragmentation and deterioration, and suppression of natural fires. Alteration of the disturbance cycle may lead to changes in vegetation structure and thus habitat suitability for breeding grassland birds. Management practices at the Mississippi Sandhill Crane National Wildlife Refuge, including the use of prescribed fire, are in need of evaluation. My study asked what frequency of prescribed burns is necessary to support breeding grassland birds and whether vegetation structure varies among burn units. In this study, bird abundance and species richness did not differ significantly among burn units and vegetation cover-type was not a strong predictor of these factors either. There was evidence of site utilization by breeding grassland birds immediately following a burn, which suggests that the bird community is able to recovery quickly post-fire and these units may serve as viable habitat for breeding grassland birds.

Padre Island National Seashore provides important habitat for wintering grassland birds, which are declining throughout their breeding range, yet oil and gas development is widespread in the park. My objective was to evaluate the effects of resource extraction on the park's grassland birds and make management recommendations based on my findings. In January-March 2007 and 2008, I surveyed 5 active, 4 abandoned, and 4 road sites to investigate the relationship between distance from disturbance (well pads, access roads) and bird abundance. I also compared abundance among the 3 site types. At each site I recorded bird numbers and species in 10-m distance bands along all transects (4 transects/well, 2 transects/road), each extending 300 m from the road or pad. At road sites bird abundance was positively correlated with increased distance from road edge, but I found no linear relationship at active or abandoned well sites. However, mean bird abundance in the first (0-30-m) distance interval of active well transects was less than half that at the second interval, and was the lowest value for all active intervals except the ninth. First-interval abundance at active wells was lower than abundance at any abandoned well interval. Road transects likewise showed low abundance in the initial interval, although unlike at active wells abundance increased steadily with distance from the center of disturbance. This trend of lower overall numbers at the first interval of active well transects was driven largely by 1 species, the meadowlark. A combination of high noise levels near active well pads (up to 80 dB) and lack of tall vegetation (on average 30% lower than the 60-90-m interval) from which to sing may have contributed to low numbers of meadowlarks, which were the only birds to sing regularly during my study period. While most birds appear to be minimally affected by resource extraction at Padre Island, to ensure minimal impacts on sensitive species I recommend: 1) reducing noise at active sites, 2) limiting disturbance to vegetation near pads and roads, 3) maintaining existing perch sites, 4) restoring all vegetation to its pre-extraction condition, 5) limiting road construction.

North American grasslands and grassland birds have declined drastically due to habitat degradation by fire suppression (i.e., woody encroachment), fragmentation, and conversion to croplands. A better understanding is needed of the relationships among disturbance regimes (e.g., fire), resultant vegetation changes, and grassland bird communities to effectively manage remaining grasslands and grassland birds. I assessed the relationship between post-fire succession, and mean relative abundance and nesting ecology of breeding grassland birds (i.e., nest-site selection and nest success) in mesquite-dominated rangeland of the Texas Rolling Plains, where prescribed fire is used as a tool to manage shrub encroachment. Brush cover, grass cover, and visual obstruction generally increased with post-fire succession, and bare ground decreased with post-fire succession. Species richness, grasshopper sparrows (Ammodramus savannarum), Cassin’s sparrows (Aimophila cassinii), and dickcissels (Spiza americana) responded positively to post-fire succession, and lark sparrows (Chondestes grammacus) responded negatively to post-fire succession.; abundance of these avian groups was low on the control sites. During 2004–2005, 90 grassland bird nests were monitored. I found conflicting results for vegetation parameters important to nest site selection and probability of nest success. For all species except lark sparrows, nest-site location was positively associated with visual obstruction and with grass or forb cover. However, the probability of nest success increased with lower visual obstruction, bare ground cover, or grass cover. Grassland bird abundance, nest-site location, and nest success had differing associations with vegetation variables. These results suggest that to effectively manage remaining grasslands for sustainable breeding grassland bird populations, managers should engage in practices that keep habitat in multiple vegetative successional stages.

Area sensitivity of North American grassland birds is a significant conservation concern; yet, its causes are not known. I used point count data from 20 tall-grass prairie patches in Southern Manitoba to assess the relative importance of patch size, edge proximity, and landscape composition on the densities and species richness of grassland songbirds. The degree to which the landscape surrounding point count plots was open, as opposed to forested or urban, had a positive effect on species richness and the densities of most focal species, and was more important than patch size, edge proximity, or habitat amount. These results suggest that landscape openness, not patch size (with which it is usually correlated) drives area sensitivity. Small grassland patches embedded in open landscapes are less susceptible to area sensitivity and may be of high conservation value for grassland birds. / February 2017