Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 132-142). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 114-122). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 84-92). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 253-266). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [74]-80).

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 41-44). Also available via the World Wide Web.

The federally threatened northern spotted owl (Strix occidentalis caurina) is the focus of intensive conservation efforts that have led to much forested land being reserved as habitat for the owl and associated wildlife species throughout the Pacific Northwest of the United States. Recently, however, a relatively new threat to spotted owls has emerged in the form of an invasive competitor: the congeneric barred owl (Strix varia). As barred owls have rapidly expanded their populations into the entire range of the northern spotted owl, mounting evidence indicates that they are displacing, hybridizing with, and even killing spotted owls. The barred owl invasion into western North America has made an already complex conservation issue even more contentious, and a lack of information on the ecological relationships between the 2 species has hampered conservation efforts. During 2007–2009 I investigated spatial relationships, habitat selection, diets, survival, and reproduction of sympatric spotted owls and barred owls in western Oregon, USA. My overall objective was to determine the potential for and possible consequences of competition for space, habitat, and food between the 2 species. My study included 29 spotted owls and 28 barred owls that were radio-marked in 36 neighboring territories and monitored over a 24-month tracking period. Based on repeated surveys of both species, the number of territories occupied by pairs of barred owls in the 745 km² study area (82) greatly outnumbered those occupied by pairs of spotted owls (15). Estimates of mean size of home-ranges and core-use areas of spotted owls (1,843 ha and 305 ha, respectively) were 2–4 times larger than those of barred owls (581 ha and 188 ha, respectively). Individual spotted and barred owls in adjacent territories often had overlapping home ranges, but inter-specific space sharing was largely restricted to broader foraging areas in the home range with minimal spatial overlap among core-use areas. I used an information-theoretic approach to rank discrete choice models representing alternative hypotheses about the influence of forest conditions and interspecific interactions on species-specific patterns of nighttime habitat selection. Spotted owls spent a disproportionate amount of time foraging on steep slopes in ravines dominated by old (>120 yrs old) conifer trees. Barred owls used available forest types more evenly than spotted owls, and were most strongly associated with patches of large hardwood and conifer trees that occupied relatively flat areas along streams. Spotted and barred owls differed in the relative use of old conifer forest (higher for spotted owls) and slope conditions (steeper slopes for spotted owls). I found no evidence that the 2 species differed in their use of young, mature, and riparian-hardwood forest types, and both species avoided forest-nonforest edges. The best resource selection function for spotted owls indicated that the relative probability of a location being selected was reduced if the location was within or in close proximity to a core-use area of a barred owl. I used pellet analysis and measures of food niche overlap to examine the potential for dietary competition between spatially associated pairs of spotted owls and barred owls. I identified 1,223 prey items from 15 territories occupied by pairs of spotted owls and 4,299 prey items from 24 territories occupied by pairs of barred owls. Diets of both species were dominated by nocturnal mammals, but diets of barred owls included many terrestrial, aquatic, and diurnal prey species that were rare or absent in diets of spotted owls. Northern flying squirrels (Glaucomys sabrinus), woodrats (Neotoma fuscipes, N. cinerea), and lagomorphs (Lepus americanus, Sylvilagus bachmani) were particularly important prey for both owl species, accounting for 81% and 49% of total dietary biomass for spotted owls and barred owls, respectively. Dietary overlap between pairs of spotted and barred owls in adjacent territories ranged from 28–70% (mean = 42%) In addition to overlap in resource use, I also identified strong associations between the presence of barred owls and the behavior of spotted owls, as shown by changes in space-use, habitat selection, and reproductive output of spotted owls exposed to different levels of spatial overlap with barred owls in adjacent territories. Barred owls in my study area displayed both numeric and demographic superiority over spotted owls; the annual survival probability of radio-marked spotted owls from known-fate analyses (0.81, SE = 0.05) was lower than that of barred owls (0.92, SE = 0.04), and barred owls produced over 6 times as many young over a 3-year period as spotted owls. Survival of both species was positively associated with an increasing proportion of old (>120 yrs old) conifer forest within the home range, which suggested that availability of old forest was a potential limiting factor in the competitive relationship between the 2 species. When viewed collectively, my results support the hypothesis that interference competition with a high density of barred owls for territorial space can act to constrain the availability of critical resources required for successful recruitment and reproduction of spotted owls. My findings have broad implications for the conservation of spotted owls, as they suggest that spatial heterogeneity in survival and reproduction may arise not only because of differences among territories in the quality of forest habitat, but also because of the spatial distribution of an invasive competitor. / Graduation date: 2012 / This pdf will not be made available until April 12th, 2012.

The conflict in the Pacific Northwest between competing visions of how federal forests should be managed resulted in a political stalemate in the early 1990s. The Northwest Forest Plan (NWFP) was initiated to resolve the demands for maintaining ecosystem processes and biological diversity with the social and economic needs for timber harvest. The foundation for the plan rested with the development of ecosystem management. The intent of this research is to explore the events which led up to the adoption of the NWFP, how it was implemented by the US Forest Service and Bureau of Land Management and the subsequent reactions to and consequences of the plan. The primary research consisted of thirty-eight semi-structured interviews with individuals responsible for the development of the initial plan, those tasked with implementing the plan and current federal agency personnel from the land management agencies and regulatory agencies. With the use of thematic analysis, key meanings were captured as expressed by the interviewees. The data was analyzed using institutional theory, capturing the organizational relations within the organizational field of the land management agencies. Research findings suggest that the NWFP was unsuccessful in meeting the goal of addressing the social and economic issues as well as the goals for ecosystem management. This dissertation explores the organizational practices and cultural meanings that led to the final instantiation of the plan. It seeks to shed light on the reasons why these goals were not met and how future forest plans can move beyond the current stalemate between conservation and preservation.