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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Home range analysis of rehabilitated and released great horned owls (Bubo virginianus) in Denton County, Texas, through radio telemetry

Johnston, Jennifer Lynn. Atkinson, Samuel F., January 2007 (has links)
Thesis (M.S.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.

The ecology and conservation of Mackinder's eagle owls (Bubo capensis mackinderi) in central Kenya in relation to agricultural land-use and cultural attitudes /

Ogada, Darcy L. January 2007 (has links)
Thesis (Ph.D. (Zoology & Entomology)) - Rhodes University, 2008.

Land cover at northern spotted owl nest and non-nest sites, east-central Coast Ranges, Oregon /

Perkins, John P. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references (leaves 71-76). Also available on the World Wide Web.

Module-based classification of OWL ontologies

Matentzoglu, Nicolas Alexander January 2016 (has links)
Classification is a core reasoning service provided by most OWL reasoners. Classification in general is hard - up to 2NExptime for SROIQ(D), the Description Logic which is underpinning the Web Ontology Language (OWL). While it has been shown that classification is practical for a wide range of inputs, there are still ontologies for which classification takes an unreasonable amount of time for purposes such as ontology engineering (frequent classifications after updates). A natural optimisation strategy is divide and conquer, that is, to decompose the ontology into subsets which are hopefully easier to classify and whose classifications can be combined into a complete classification of the whole ontology. Unfortunately, an arbitrary subset may not be self-contained, i.e. it might be missing information that is needed to determine entailments over its signature. Moreover, such a subset can be potentially harder to classify than the whole ontology. In order to mitigate those problems, classification preserving decompositions (CPDs) must be designed with care that they support complete classification which is, in practice, more efficient than monolithic classification. Locality-based modules are subsets of an ontology that provide certain guarantees with respect to the entities (concepts, roles) in its signature - in particular, modules are self-contained. In this thesis we explore the use of syntactic locality-based modules for underpinning classification-preserving decompositions. In particular, we empirically explore their potential to avoid subsumption tests and reduce subsumption test hardness and weigh those benefits against detrimental effects such as overhead (for example the time it takes to compute the decomposition) and redundancy (a consequence of potentially overlapping chunks in the decomposition). The main contributions of this thesis are an in-depth empirical characterisation of these effects, an extensible framework for observing CPDs in action up until a granularity of individual subsumption tests, a large, public corpus of observations and its analysis and insights on experimental methodologies around OWL reasoning.

Habitat selection, reproductive success, and site fidelity of burrowing owls in a grassland ecosystem

Ronan, Noelle A. 21 February 2002 (has links)
I used a comparative and experimental approach to examine nest habitat selection, reproductive success, and nest site fidelity of burrowing owls (Athene cunicularia) in a large, non-fragmented grassland in southwest California. In 1999, I compared habitat characteristics between nest sites (n = 31) and randomly selected, unoccupied burrows (n = 31) in the local vicinity of the nest (paired burrows). In 2000, I compared habitat characteristics between nest sites (n = 33) and randomly selected, unoccupied burrows (n 32) within the study area (unpaired burrows). I examined reproductive success and variation in nest habitat characteristics, diet quality, and intraspecific competition using data from 1998, 1999, and 2000. I experimentally (n = 11 control and 11 treatment nests) assessed the effect of satellite burrow (multiple auxiliary burrows near the nest) use on productivity and behavior. I found little variation in habitat between nest sites and unoccupied burrows. Habitat selection was not strong when nests and unoccupied burrows were spatially correlated (paired burrows). However, nest sites had a larger number of large diameter burrows, satellite burrows, and perches than the unpaired burrows. Nest success ( I young fledged) and productivity (the number of young alive at 14 -21 days) varied substantially among some years, though the habitat variables I tested did not explain reproductive success when both failed and successful nests were evaluated. When nests were successful, productivity was influenced by rodent consumption. Nest fidelity within the breeding season was highly correlated with nest success. Nest abandonment occurred at 83% (n = 15 of 18), 92% (n = 12 of 13), and 83% (n = 20 of 24) of the failed nests in 1998, 1999, and 2000, respectively. Results of the experimental manipulation of satellite burrow access showed that productivity did not differ between groups but demonstrated that burrowing owls will adjust their behavior to use satellites. Owls in the treatment group (71%; n = 5 of 7) responded by moving their families to areas with access to satellite burrows but none of the control group owl families moved. This study illustrates the importance of identifying critical factors affecting reproductive success of burrowing owls in large grasslands. Maintenance of burrowing mammal populations to provide nest and satellite burrows will be important for protecting burrowing owls. Also, temporal dynamics influenced reproductive success. Habitat characteristics that enhance foraging ability may benefit productivity, especially in years of low rodent numbers. Furthermore, temporal variation in nest success may lead to low nest site fidelity. / Graduation date: 2002

Competitive interactions and resource partitioning between northern spotted owls and barred owls in western Oregon

Wiens, J. David 02 March 2012 (has links)
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.

Evaluating space use and pesticide exposure risk for burrowing owls in an agricultural environment

Gervais, Jennifer A. 22 April 2002 (has links)
Large burrowing owl (Aihene cunicularia) populations exist in areas of intensive agriculture in California, and pesticide exposure has been identified as a potential threat to population persistence. I evaluated breeding season use of agricultural fields by adult male owls using radio telemetry, and examined egg contaminant residues to estimate population-level effects on reproduction and survival. Reproduction and survival were estimated annually, and an index of diet was inferred from pellet samples. A total of 11 adult males in 1998 and 22 in 1999 were successfully radio-tracked. Mean fixed kernel home range sizes were 172 ha (SE=68) in 1998 and 98 ha (SE=16) in 1999. Pellet analyses indicated a substantial increase in the numbers of rodents consumed in 1999, associated with an observed population explosion of California voles (Microtus calfornicus). Distance to the nest was the most important factor in differentiating between foraging and random locations, and there was no tendency to select or avoid any cover type. Owls did forage in agricultural fields, but I failed to find evidence of selection or avoidance of fields recently treated with pesticides. A total of 92 eggs were collected over 5 years. Egg contaminants were generally limited to the presence of p,p'DDE, which fluctuated by 4 orders of magnitude among years, from 0.05 ug/g to 33 ug/g fresh weight p,p'DDE. There was a general pattern of decline in egg residues over time for individual birds. The levels of p,p'DDE I documented did not appear to have any effect on either productivity or survival of adult females, nor were they clearly related to diet. I modeled the effects of various pesticide exposure impacts on demographic rates and determined that exposure rates based on field data would lead to relatively minor declines in population growth rate. An elasticity analysis of burrowing owl demographic parameters revealed a variable pattern, but generally indicated that factors influencing anyone of the demographic parameters of burrowing owls can have a substantial impact on population growth rate. / Graduation date: 2002

Secure Remote Access to Telemetry: A Study in How to Allow Remote Access to Satellite Telemetry Data

McClinton, Arthur T., Jr. 10 1900 (has links)
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The need to allow remote access to telemetry data from closed networks has long existed. To ensure the correct engineers are available for anomaly resolution, NOAA developed the Secure Remote Access Server (SRAS) to allow transfer of satellite telemetry to an external secure server. SRAS uses one-way links to protect the ground system and secure communications for all communications with the user. After the SRAS was developed, a similar system was developed to support file transfers. This paper provides an overview of these systems and lessons learned in the development of one-way fiber systems.

OWL Ontology for Scalable Vector Graphics

Mathis, Regina Mitzie 01 January 2014 (has links)
Using the World Wide Web of today, searching for a graphic pertaining to a particular subject domain or in response to a specific query is a difficult task. A typical search for a graphic related to a specific subject matter or query may yield hundreds or thousands of Web resources, few of which relate to the intended meaning. The primary goal of the completed dissertation is to develop and assess the feasibility of using a global ontology for Scalable Vector Graphics (SVG) written in the Semantic Web markup language Web Ontology Language (OWL). SVG is an eXtensible Markup Language (XML) based technology used to describe two-dimensional graphics. SVG has the ability to fully scale images without loss of resolution, provide file sizes that are independent of resolution, represent text as text strings allowing the graphic to be fully searched for content, and support a rich set of geometrical primitives. An SVG OWL ontology provides three benefits. First, the ontology enables powerful semantic search engines to quickly and efficiently pinpoint SVG graphics and relate these graphics to specific knowledge domains. Second, the ontology enables semantic search engines to understand the content of a SVG graphic and infer relationships between the content of the graphic and specific domains. Lastly, enabling SVG graphics to be annotated in varying levels of abstraction allows the graphic to be reused in other contexts. The research methods included developing the framework for the model, identifying the entities to be used in the ontology, representing the conceptual elements using Unified Modeling Language (UML), converting the UML to OWL, evaluating the ontology to ensure that it meets the requirements initially presented, developing a working system based on the ontology and testing this system, and documenting the development process. Regarding experimental results, a total of 69 queries were applied to a set of 500 images representing a range of both primitive and derived spatial properties. Both recall and precision were perfect, indicating the feasibility of effective ontology-based search for annotated vector graphics through this approach. The question of scalability to more complex and realistic settings remains for future research.

The causes of egg hatching failures in wild birds

Burg, A. B. van den January 2001 (has links)
No description available.

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