Thesis (Ph. D., Environmental Science)--University of Idaho, May 2007. / Major professor: J. Michael Scott. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Common Ravens (Corvus corax L.) have been implicated as significant predators on the eggs of waterfowl and shorebirds on Malheur National Wildlife Refuge. Malheur Refuge, located in southeastern Oregon on the northern edge of the Great Basin, is one of the largest waterfowl refuges in the United States and is an important breeding area for waterfowl. In order to provide fundamental information on which a sound raven management plan could be based, research was conducted from 1975-1977 on aspects of population density, brood phenology, nesting success, seasonal use of the study area, roosting behavior, and food habits of ravens on and near the refuge. Nesting density was determined to be one pair per approximately 25 km2 . Most nests occurred in rimrocks, but trees and abandoned human structures were also used. Investigation of 87 nests revealed that the incubation period was 21 + 1 days. Incubation began with the laying of the first egg; hatching was asynchronous. Nesting period was 41 + 3 days. An original method of age-classing ravens is described. A total of 266 ravens was marked with patagial tags. Observation of marked individuals as far as 480 km from the study area suggests considerable mobility in the population. Population numbers vary seasonally, peaking in the winter. The Harney Basin is the location of an exceptionally large winter roost for ravens. Analysis of food remains, collected from 34 nests, indicates that ravens have varied diets and that there are significant differences in the diets of ravens nesting in different habitats. A correlation exists between the proportion of the diet that is avian material and the proximity of the raven nest to waterfowl production areas. Based on these findings, suggestions are offered for a management plan for Common Ravens on Malheur National Wildlife Refuge.

Lepidium latifolium L. (perennial pepperweed, LEPLA) is an exotic invader throughout western North America. At Malheur National Wildlife Refuge (MNWR) in southeast Oregon, it has invaded about 10% of meadow habitats that are important for wildlife. This study's objective was to determine the most effective and least environmentally harmful treatment to control this weed and restore native vegetation using integrated pest management techniques. During summer 1995, nine 0.24-ha plots in three meadows infested with L. latifolium at MNWR were randomly assigned to a treatment with metsulfuron methyl herbicide, chlorsulfuron herbicide, disking, burning, herbicide (metsulfuron methyl or chlorsulfuron) then disking, herbicide (metsulfuron methyl or chlorsulfuron) then burning, or untreated. Changes in L. latifolium ramet densities and basal cover of vegetation, litter, and bare soil were evaluated in 1996 and 1997. Sheep grazing was evaluated as a treatment for reduction in flower production along roadsides and levees during summer 1997. Revegetation treatments of seeding, transplanting or natural (untreated) revegetation were attempted at plots treated with chlorsulfuron, disking, chlorsulfuron then disking, and at untreated plots from October 1996 through September 1997. Chlorsulfuron was the most effective control treatment with greater than 97% reduction in L. latifolium ramet densities two years after treatment. Metsulfuron methyl was an effective control (greater than 93% reduction) for one year. Disking was ineffective. Burning was ineffective at the one site where sufficient fine fuels existed to carry fire. Herbicide treatments were associated with increased grass and reduced forb cover. Disking was associated with reduced grass and litter cover. Disking combined with either herbicide treatment was associated with reductions in all plant cover (49 to 100%), increased bare ground, and invasion by other weedy species such as Cirsium arvense (L.) Scop. (Canada thistle, CIRAR) and Bromus tectorum L. (cheatgrass, BROTE). Ungrazed L. latifolium averaged 4513 flowers per ramet. Sheep grazing reduced L. latifolium flower production by at least 98%. Revegetation treatments were unnecessary in sites treated with chlorsulfuron and were ineffective at all treatment sites. / Graduation date: 2000

A vegetation monitoring program was initiated at Big Oaks National Wildlife Refuge (Big Oaks NWR) to help understand the effects of fire management on critical wildlife habitat. The objectives of this study were to produce a baseline description of plant community structure and composition and to describe the landscape-level impacts of fire management within the refuge. These grassland communities are important for managing rare grassland wildlife species, especially Henslow's sparrows. Permanent plots were established in three managed grassland communities. Information on plant community species composition and structure was collected during 2000-2001. Andropogon viginiana and Solidago juncea were the dominant plant species in the permanent plots. Rhus copallinum and Liquidamber styraciflua were the dominant woody species. Changes in landscape structure were determined using aerial photographs and a geographic information system (GIS). Vegetation data layers were created for 1995 and 1998 with vegetation patches classified using the National Vegetation Classification System (NVCS). Field data was collected during 2000 and 2001 to validate the data layers. Changes in composition and structure of nine vegetation classes were compared between burned and unburned areas. Percent cover of grassland area increased while sparse woodland and shrubland decreased during the study period. The amount of total patches and total edge declined in the burn areas. Mean grassland patch size increased while the number of grassland patches and grassland edge decreased in the burn areas. Therefore, the grassland areas within the burn units were more homogeneous in 1998. The results of this study were related to Henslow's sparrow population estimates in the fire management units.

Several invasive woody plants grow in forest fragments at Muscatatuck National Wildlife Refuge in Seymour, Indiana. The objective of this study was to determine what woody species were growing in two upland forests and to assess the level of dominance that invasive species had in these areas. The variables of depth into the forest and directional aspect were also considered. Thirty-two belt transects were sampled and 54 woody species were found, including six invasive species: Ailanthus altissima (tree-ofheaven), Berberis thunbergii (Japanese barberry), Elaeagnus umbellata (autumn olive), Lonicera japonica (Japanese honeysuckle), Lonicera maackii (amur honeysuckle), and Rosa multiflora (multiflora rose). Importance values were calculated as an indicator of relative species dominance. Detrended Correspondence Analysis and Cluster analysis suggested that the invasive species were grouped on the forest edge transects; aspect was not found to be a determinant in where invasive species grew. Correlation coefficients demonstrated a significant difference between transect depth and the following variables at both forests: woody species density per transect, invasive species dominance, Elaeagnus umbellata density per hectare, and Lonicera japonica dominance. Rosa multiflora was one of the three most dominant understory species in both forests; on the edge transect, it was one of the top two. Soil temperatures were also measured at each transect, but no consistent trends were found within the data. In light of resources available, it is suggested that land managers focus on controlling Rosa multiflora and Ailanthus altissima. / Department of Natural Resources and Environmental Management

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.

Eastern Kingbirds (Tyrannus tyrannus) breed from coast to coast in North America and build open-cup nests in trees. They have been extensively studied across most of their range and have only on occasion been documented to reuse a nest from a previous season. However, at Malheur National Wildlife Refuge (MNWR), located in southeastern Oregon, ~10 % of female Eastern Kingbirds reuse old nests of mainly American Robins (Turdus migratorius). In an attempt to address why nest reuse is so common at MNWR, I used artificial nests to evaluate two hypotheses as to why nest reuse is common in this breeding population. The first hypothesis states that Eastern Kingbirds reuse nests to save time and/or energy (TES) and the second one states nest reuse occurs because there is a shortage of suitable nest sites (NSS). I was able to reject the TES hypothesis because artificial nests provided no apparent reproductive benefits to Eastern Kingbirds, except that if a nest had failed it took less time to lay a replacement clutch after an initial failure if an artificial nest was used instead of building a new nest. A more reasonable explanation is that Eastern Kingbirds face a limited availability of suitable nest sites. With this in mind, I took vegetation measurements to address the hypothesis that Eastern Kingbirds make adaptive choices when selecting a nest site, in which case they would choose sites that increase their probability of breeding successfully. Successful nests, both natural and artificial, were placed higher in a tree and on a steeper angled nest branch than their failed counterparts. Those findings suggest that Eastern Kingbirds make adaptive choices when selecting a nest site.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xiv, 156 p. : col. ill., maps (part col.). Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Ecology and Evolution." Includes bibliographical references (p. 137-157).