Dissertations / Theses on the topic 'Spotted owl'

Ecologists suspect that owls select specific areas based on prey availability. My objective was to determine and compare distributions and abundances of Mexican spotted owl prey species' within different vegetation types in the canyons and mesas of the Manti-LaSal National Forest in Utah. I conducted live-trapping during summer and fall, 1994-95. Woodrat species (Neotoma spp.) are the Mexican spotted owls primary prey species as determined by percent biomass. Peromyscus spp. are also important in terms of frequency. Woodrats were only captured in the canyons and were primarily captured within the pinyon (Pinus spp.) - juniper (Juniperus spp.) vegetation type. The Mexican spotted owls in southeastern Utah spend >75% of their time within the canyons and forage within pinyon-juniper stands in the canyons. Maintaining the present state of pinyon-juniper stands within the canyons may benefit Mexican spotted owl populations in the Manti-LaSal National Forest.

The Forest Inventory and Analysis (FIA), the United States’ forest census, measured sixty-six Mexican spotted owl nest stands in order gain insight into the structure and composition of the nest habitat of this threatened species. I used these data, along with the greater FIA database and the Forest Vegetation Simulator to explore questions surrounding the management of Mexican spotted owl habitat, specifically how to balance the objective of sustaining and enhancing nest habitat in face of increasing forest fire size and severity in the Southwest. My research consisted of three studies. The first study quantified the structure and composition of the Mexican spotted owl nest stands and scrutinized current evaluation criteria of nest habitat. The second study estimated how much of the Southwestern landscape is at risk to high-severity crown fire and how much of the landscape is suitable Mexican spotted owl nest habitat. The third study modeled forest dynamics and silvicultural intervention in potential Mexican spotted owl nest stands. The purpose of this research is to assist in management of Southwestern forests in order to decrease fire size and severity while sustaining and enhancing current and future Mexican spotted owl nest habitat.

On the Colorado Plateau, environments occupied by Mexican spotted owls (Strix occidentalis lucida) receive intense levels of recreational activity that could adversely effect their behavior and reproductive success. Any spatial restrictions on recreational activities in these narrow canyons would likely eliminate all recreational activity within a given canyon. We assessed changes to activity budgets and nest attendance caused by hikers (Chapter 1) and examined factors that influenced flush responses of roosting owls to hikers (Chapter 2). We conclude that high levels of recreational activity in nesting habitat may be detrimental to Mexican spotted owls and recommend a 205-m radius buffer zone around occupied nests. Based on responses of roosting owls to hikers, we established response thresholds as a basis for exploring management options that will maximize protection of owls and minimize restrictions to recreationists.

<p> 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. </p><p> 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. </p><p> 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.</p><p>

I studied the habitat characteristics of Mexican Spotted Owls (Strix occidentalis lucida), a federally threatened species, in the canyonlands region of southern Utah. Vegetative and geologic features were measured within 10m wide belt plots at each current or historic nest/roost site. Based on our findings, past research, and species life history characteristics, I constructed a species distribution model (SDM) predicting Mexican Spotted Owl distribution in Utah for the Colorado Plateau region. The SDM was generated using the following inputs as important habitat variables: elevation, aspect, surface ratio, curvature, slope, geology, and vegetation. Program R was used for model development and generation. The SDM was generated using an ensemble model approach by combining three modeling techniques: random forest, logistic regression, and maximum entropy. This study combines measured habitat characteristics, with sophisticated geographic information system (GIS) tools and SDMs to provide managers with an informative and useful toolkit for Mexican Spotted Owl conservation. Chapter 2 discusses modeling techniques and SDM development. I detail how individual models were constructed using random forest, logistic regression, and maximum entropy and how these were combined into an ensemble model. Final models indicated that several vegetative and geologic characteristics were considered important habitat characteristics for predicting Mexican Spotted Owl presence within the Colorado Plateau. The SDMs produced eight distribution maps predicting Mexican Spotted Owl presence and probability of occurrence in Utah for the Colorado Plateau region. Chapter 3 explains the use of SDMs by managers and synthesizes findings of measured habitat characteristics for southern Utah. For habitat characteristics I measured a combination of vegetative and geologic features within 10m wide belts at current and historic Mexican Spotted Owl sites. Vegetative features measured included: height and species of all trees and shrubs, position of tree or shrub within plot, presence of canopy cover, and tree diameter at breast height (DBH). Geologic features measured included: geologic formation type, wall height, structure type, number of caves, and number of solution cavities. I found that canyon width and density of vegetation > 2.5 m tall were significantly correlated with Mexican Spotted Owl presence.

The Mexican spotted owl (Strix occidentalis lucida) was listed as &quot;threatened&quot; in 1993 by the U.S. Fish and Wildlife Service. In Utah, the spotted owl is associated with rocky canyons that attract high levels of human recreation. Recreation could potentially have negative effects on the owl. I investigated roost behavior, territorial occupancy rates, and reproduction in canyon habitats that differed in recreation level and habitat condition (e.g., xeric versus mesic environments). Surveys were conducted in four areas in Utah: Zion and Capitol Reef National Parks, Grand Staircase-Escalante National Monument, and the Cedar Mesa-Elk Ridge highland. In Chapter 2, I evaluated possible differences in behaviors by fledglings across different levels of recreation. Fledgling diurnal behaviors were dependent on recreation level (P &lt; 0.05). Fledglings in both recreation classes spent approximately = 50% of their time roosting, but fledglings associated with high-recreation territories spent more time in maintenance behaviors (13% vs. 4%) and less time in vigilant behaviors (29% vs. 35%) than did those in low-recreation territories. In Chapter 3, results from a top-ranked regression model indicated potential association between owl site occupancy rates and habitat type, with mesic sites showing higher occupancy than xeric sites in 2008: 0.75 (95% CI = 0.57 - 0.87) and 0.50 (95% CI = 0.27 - 0.73). Recolonization rate was 0.53 (95% CI = 0.28 - 0.76) for mesic sites and 0.10 (95% CI = 0.02 - 0.37) for xeric sites. Extinction rate was constant across years and sites (0.25; 95% CI = 0.15 - 0.39). Detection probability was 0.89 (95% CI = 0.82 - 0.94) across all three years of study. The number of fledglings per pair was greater in 2009 (0.94) than 2008 (0.25) and 2010 (0.50). My results suggest that recreation could have altered diurnal roost behavior of fledglings but was not related to occupancy and reproduction of Mexican spotted owls.

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.<br>Graduation date: 2012<br>This pdf will not be made available until April 12th, 2012.

This study describes the composition of forest landscapes surrounding northern spotted owl (Strix occidentalis caurina) nests in the central Cascade Mountains of Oregon. I compared forest composition around 126 owl nests in 70 pair territories with forest composition around 119 points drawn randomly from all terrestrial cover-types, and around 104 points drawn randomly from the old-forest (closed canopy, > 80 yrs) cover type. All nest sites and random points were drawn from U.S. Forest Service lands and were not drawn from privately owned lands or Wilderness Areas. Forest cover was classified on a Landsat Thematic Mapper image. I quantified the percentage of old-forest within 200 concentric circular plots (0.04-5.0-km radii), centered on each analyzed point, using a geographic information system. I used logistic regression to make spatially-explicit inferences. Owl nests were surrounded by more old-forest when compared to points drawn randomly from all terrestrial cover types: there was significantly (P<0.05) more old-forest around the owl nests in plots as large as 1.79 km in radius. When compared to points drawn randomly from the old-forest cover type, owl nests were surrounded by significantly (P<0.05) more old-forest in plots with 0.17-0.80-km radii. Exploratory analyses suggest that the landscape scales most pertinent to northern spotted owl nest site positioning in this study area appear to be (in descending order): the surrounding 10-15 ha (~200-m radius), the surrounding 25-30 ha (~300-m radius), the surrounding 200 ha (800-m radius), and possibly the surrounding 700 ha (1,500-m radius). This study supports the assertion that northern spotted owls are strongly associated with older forests. The results also indicate that owl nests are most associated with higher proportions of old-forest near the nest implying that the arrangement of habitat is important for nest-site selection/positioning Since spotted owls in the central Cascade Mountains of Oregon are known to have home-ranges that average 1,769 ha, it is important to recognize that these results apply to nest-site selection/positioning on the landscape and not to the amount of habitat necessary for pair persistence or successful reproduction.<br>Graduation date: 1998

A spatially explicit forest harvesting and individual-based population simulation model has been developed. This model was used to assess the response of rare or endangered forest wildlife to forest harvesting policies and conservation options. A specific focus was on the examining the efficacy of proposed management options for the northern spotted owl population in British Columbia. The forest harvest simulation component was used to construct spatial and temporal patterns of logging activities in the Fraser and Soo timber supply areas. Forest simulations were based on a forest inventory database of 25-ha resolution, and simulated harvests were subject to constraints imposed by the Forest Practices Code and wildlife conservation options. The delineation of breeding territories over this database was done using a submodel that maps likely territory areas following geographic constraints of the landscape, resulting in a "mosaic" of variously shaped territories. This allowed for aggregation of the finer scale forest-state data into simple indices of habitat quality for owls. These indices were updated on a yearly basis as the forest either aged or was harvested. The individual-based population simulator used "coarser" territory/habitat maps to simulate dispersal, location and fates of individual female owls (i.e., breeding pairs). Simulations suggest that a major limiting factor is the low survival rate of dispersing juvenile owls. The proposed management plans do not adequately address this problem and may, in fact, be detrimental to the owl population. These small conservation areas increase logging pressure on the surrounding areas. As a result, juveniles are forced to disperse from their natal habitats into marginal habitats where the risk of mortality is increased. Reduction in the annual allowable cut is more important than any proposed configuration of Spotted Owl Conservation Areas.

碩士<br>國立臺灣海洋大學<br>水產養殖學系<br>105<br>Two experiments were conducted to investigate the effects of dietary supplementation of linseed meal and replacement of fish oil by soybean oil on the growth and fatty acids composition of orange-spotted grouper, Epinephelus coioides. The effects of diets containing different levels of linseed meal (0, 3, 6, 9 and 12%) on the growth performances and body fatty acids composition of orange-spotted grouper, Epinephelus coiodes were investigated in experiment Ⅰ. Orange-spotted groupers were fed five isonitrogenous (45%), isoenergetic (335 kcal/100g) and isolipid (11%) diets for six weeks. Twelve experimental fish (initail weight was 2.40g) per tank were randomly distributed into 15 indoor glass tanks (60 L). Each treatment diet was distributed to triplicate groups. The growth performance of groupers fed diet containing 12% linseed meal was significantly higher than that of control diet and diet containing 3% linseed meal. Fish fed diets containing 6 and 9% linseed meal showed no significant difference. The muscle and liver of fatty acid profile reflected the dietary lipids. There was a notable increasing 18:3n-3 of muscle and liver with increasing dietary linseed meal, however 20:5n-3 and 22:6n-3 followed an opposite trend.The effects of replacement of fish oil by soybean oil (0, 20, 40, 60, 80 and 100%) on the growth performances and body fatty acids composition of orange-spotted grouper, Epinephelus coiodes were investigated in experiment Ⅱ. Orange-spotted groupers were fed six isonitrogenous (47%), isoenergetic (342 kcal/100g) and isolipid (10%) diets for six weeks. Twelve experimental fish(initail weight was 3.29g) per tank were randomly distributed into 18 indoor glass tanks (60 L). Each diet was distributed to triplicate groups. The growth performance of groupers fed diet with the replacement of 80% fish oil by soybean oil was significantly higher than that of control diet and diet with the replacement of 100% fish oil by soybean oil. Fish fed diets with the replacement of 20, 40 and 60% fish oil by soybean oil showed no significant difference. The muscle and liver of fatty acid profile reflected the dietary lipids. There was a notable increasing 18:2n-6 of muscle and liver with increasing the replacement of fish oil by soybean oil, however 20:5n-3 and 22:6n-3 followed an opposite trend. After experiment Ⅱ, ten experimental fish were randomly selected from each treatment tank for cold shock.The water temperature was decreased from 29℃ to 10℃ at a rate of 1℃·day-1. The results showed that the semi-lethal temperature of the grouper increased with increasing the replacement of fish oil by soybean oil. The semi-lethal temperatures were 10.00℃, 10.33℃, 11.27 ℃, 11.33℃, 11.43℃ and 12.07℃, respectively. After cold shock, there was a increasing n-3 highly unsaturated fatty acid of muscle and liver.

A comprehensive evaluation of the effects of an nC24 agricultural mineral oil (AMO) on tritrophic interactions between French bean Phaseolus vulgaris cv. Redlands Pioneer [Fabales : Fabaceae ], two spotted mite (TSM) Tetranychus urticea Koch [Acari: Tetranychidea] and the predatory mite Phytoseiulus persimilus Atheus-Henriot [Acari: Phytoseiidae] was conducted under laboratory conditions.<br>Doctor of Philosophy (PhD)

A comprehensive evaluation of the effects of an nC24 agricultural mineral oil (AMO) on tritrophic interactions between French bean Phaseolus vulgaris cv. Redlands Pioneer [Fabales : Fabaceae ], two spotted mite (TSM) Tetranychus urticea Koch [Acari: Tetranychidea] and the predatory mite Phytoseiulus persimilus Atheus-Henriot [Acari: Phytoseiidae] was conducted under laboratory conditions.