Thesis (M.Sc. (Wildlife Management (Animal and Wildlife Sciences)) -- University of Pretoria, 2009. / Abstract in English. Includes bibliographical references.

Thesis (Ph. D.)--Göteborg University, 2003. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M.S.)--Texas A & M University, 2003. / "Major Subject: Wildlife and Fisheries Sciences." Title from author supplied metadata. Includes bibliographical references.

Thesis (M.S.)--Texas A & M University, 2003. / "Major Subject: Wildlife and Fisheries Sciences." Title from author supplied metadata. Includes bibliographical references.

Thesis (M.S.) in Ecology and Environmental Sciences--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 38-41).

Thesis (M.S.)--Texas A & M University, 2003. / "Major Subject: Wildlife and Fisheries Sciences." Title from author supplied metadata. Includes bibliographical references.

<p> Individual variation and fitness are the cornerstones of evolution by natural selection. The trophic niche represents an important source of phenotypic variation on which natural selection can act. Although individual variation is fundamental to species-level ecological and evolutionary change, individual variation is often ignored in population-level approaches to wildlife ecology, conservation and management. Failing to link individual resource use to fitness or to biological outcomes related to fitness limits us to managing for the average resource needs of a population, which may be insufficient for protecting the diversity of resource use within populations and the underlying eco-evolutionary processes that generate that diversity. My goals were to provide insights into the mechanisms that generate and constrain intrapopulation trophic niche variation, evaluate whether linkages exist between individual biological outcomes and variation in food habits across the range of resources consumed within generalist consumer populations and examine how that variation manifests in population-level responses. </p><p> I investigated the causes and physiological consequences of intrapopulation trophic niche variation in two generalist consumers, the American black bear (<i>Ursus americanus</i>) and brown bear (<i>U. arctos</i>) across three sites in British Columbia, CAN and at one site in Alaska, USA. My primary tools included stable isotope analysis to estimate diet, enzyme-linked immunoassay of hair to quantify the hormone cortisol for indexing physiological stress, and genetic analyses to identify individuals, species, and sex and to estimate ancestry. I found that individual differences in resource use can result in similar biological outcomes and that similar resource use can result in different biological outcomes. Intra- and interspecific competition, sex-based differences in nutritional and social constraints and annual variation in food availability all influenced trophic niche variation and the resultant biological outcomes. I also found evidence of a link between intrapopulation trophic niche variation and population genetic structure. My results highlight the diverse ecological drivers and diverse consequences of trophic niche variation, which further illuminates why the trophic niche is a nexus for eco-evolutionary dynamics.</p>

<p> Western Screech-Owls (<i>Megascops kennicottii</i>) are small, nocturnal owls that occur year-round throughout most of the Trans-Pecos region in West Texas, and are associated with deciduous woodlands and riparian habitats. Roadside nocturnal callback surveys, were established along well-defined trails within the Davis Mountains Preserve, and took place from May until August for two years to ascertain the relative abundance of Western Screech-Owls within the property. Abundance indices (birds detected/visit/station) were calculated for both survey seasons. Radiotelemetry was incorporated to determine certain life-history information, while habitat was characterized from both survey and telemetry sites. Occupancy models with detection probabilities were created using Program PRESENCE based on collected presence-absence data. Based on criteria for suitable screech-owl habitat previously defined in the literature, several models were also generated within ArcGIS to compare with the field data and to help predict areas of occupancy within the property. Owl abundance averaged 1.05 owls/point in 2013 and 0.82 owls/point in 2014. Six owls were marked during the study, and 3 of 6 locations were confirmed as daytime roosting sites. Statistically, there were no significant differences between occupied survey sites and telemetry sites, with only the percentage of canopy being significantly different with a mean difference of 9.32, <i> t</i>₄₂ = -2.36, <i>p</i> = 0.023. Both owls and transmitters were discovered in dense juniper-oak mottes on north-facing slopes, indicating a preference for dense, short, closed canopy areas for roosting. Overall vegetative ground cover for the two seasons averaged 54% and 48%, respectively. It was concluded that none of the included covariates in the models influenced either occupancy or detection probabilities, though detectability demonstrated an overall trend based on time of night. GIS models did not reveal any variable that strongly influenced owl occupancy but did correspond with results from previous literature.</p>

<p>White-tailed deer (<i>Odocoileus virginianus</i>) are aesthetically and economically important to landowners in Texas. Deer herd health, productivity and survivability decline when population size exceeds the available forage. During stressful times, such as dry winter periods, nutrition is limited and forage availability decreases drastically. White-tailed deer winter diets are mainly comprised of browse species because herbaceous production decreases as winter progresses. The objective of this study was to determine the influence of winter progression on nitrogen (N) and fiber concentration as well in-vitro organic matter disappearance (IVOMD) (using white-tailed deer rumen liquid) of six browse species of moderate to high forage importance. Woody plant samples were collected during pre-frost, mid-winter, and late winter from four (replications) properties in the Cross Timbers of Texas, USA over 2 years. There was a difference between years (P &le; 0.05). There was an interaction (P &le; 0.05) between species and season for all forage values. Nitrogen, a desirable nutrient, decreased as winter progressed, IVOMD decreased as fiber increased with winter progression in five of the six browse species. The only exception was evergreen live oak (<i>Quercus virginiana</i> Mill.) which kept its leaves throughout winter and maintained an average 1.33% N with lowest fiber levels and highest IVOMD in late winter. Results confirm that nutritional value of browse, especially N and fiber, decreases after the first freeze when most browse species shed leaves. It also supports the need for plant biodiversity in white-tailed habitat that supports adequate year-round white-tailed deer nutrition. </p>

I quantified nocturnal activity of female desert mule deer (Odocoileus hemionus crooki) in the Belmont and Bighorn Mountains, Arizona, 1990. I determined seasonal differences in percent of time active and distances moved at night from locations of radio-collared deer. I compared nocturnal home ranges and habitat use to those obtained from daytime locations. Activity differed among seasons (P = 0.046). Nocturnal activity was greatest in spring and summer, and decreased in winter. Movement distances also varied with seasons (P = 0.045). Most of the area of nocturnal home ranges (88%) fell within daytime home ranges. Use of habitat in relation to availability was consistent between day and night for 6 of 8 vegetation associations. Use of disturbed sites increased at night (P < 0.01).