In the Gulf Coastal Prairie and Marsh region of Texas, historic archaeological sites are often obscured by dense vegetation resulting in extremely limited surface visibility. In an environment such as this, historic sites can only be detected by the presence of above-ground features such as architectural remains and landscaping. Although not standard among cultural resource management firms, the use of historical aerial photography and informant interviews can be effective and efficient pre-field strategies for locating sites in this region. Identification of such sites is further enhanced by an in-depth understanding of the characteristic remains of pier and beam construction, which was commonly utilized in 19th-century southeast Texas farmsteads. Four 160-acre grants located in the Addicks Reservoir, Harris County, Texas were used as a case study to test the effectiveness and efficiency of these pre-field research strategies. Each of these tracts was associated with the mid 19th-century establishment of the German immigrant community of Bear Creek, and each tract contained the remnants of farmsteads where structures had often been removed or relocated leaving little above-ground remains to be discovered using standard survey techniques. A 1915 topographical map and a 1930 aerial photograph of the area were employed together with accounts of former residents and descendants of former residents that indicated locations of former farmsteads on each of these tracts. Additional archival research, including U.S. Army Corps of Engineers acquisition files for Addicks Reservoir, was conducted prior to a field “ground-truthing” survey of the properties. As a result, all six of the historic sites that appear on a 1930 aerial photograph of the area were located and documented. One historic site that appeared on a 1915 topographical map of the area but did not appear on the 1930 aerial photograph was not located.

No description available.

Accumulation of dynamic and thermodynamic forces in the Arctic are decreasing the extent of thin annual sea ice which polar bear rely on for survival. It is imperative that we identify the preferred habitat of polar bears to fully understand their future requirements. In this thesis, surveys of polar bear tracks and the surrounding sea ice variables, at various scales, were recorded. Sea ice roughness was measured through surveys of the sample area in situ, with an electromagnetic induction (EM) system (IcePIC) mounted to a helicopter, and analyzed through advanced synthetic aperture radar (ASAR) images of the study area. In situ Polar bear tracks provided a limited association with the EM sea ice roughness and a negative association to ASAR sea ice roughness. Results indicate a significant association between EM mean values and ASAR brightness means. In addition, EM statistics and ASAR texture statistics were correlated through a best fit regression model. These associations display a remote method to identify preferred polar bear habitat and provide a potential linkage between the regional (EM) and remotely sensed (ASAR) assessment of sea ice roughness.

Accumulation of dynamic and thermodynamic forces in the Arctic are decreasing the extent of thin annual sea ice which polar bear rely on for survival. It is imperative that we identify the preferred habitat of polar bears to fully understand their future requirements. In this thesis, surveys of polar bear tracks and the surrounding sea ice variables, at various scales, were recorded. Sea ice roughness was measured through surveys of the sample area in situ, with an electromagnetic induction (EM) system (IcePIC) mounted to a helicopter, and analyzed through advanced synthetic aperture radar (ASAR) images of the study area. In situ Polar bear tracks provided a limited association with the EM sea ice roughness and a negative association to ASAR sea ice roughness. Results indicate a significant association between EM mean values and ASAR brightness means. In addition, EM statistics and ASAR texture statistics were correlated through a best fit regression model. These associations display a remote method to identify preferred polar bear habitat and provide a potential linkage between the regional (EM) and remotely sensed (ASAR) assessment of sea ice roughness.

Recent research indicates climate change will be amplified in Polar Regions, which will cause decreases to sea ice thickness and extent throughout the Arctic. Polar bears (Ursus maritimus) will be directly affected by changes to Arctic sea ice conditions because they rely on the ice substrate for numerous aspects of their life history. Perhaps of most importance, polar bears use the sea ice platform to access their main prey, pagophilic seals. Determining specific effects of climate-induced environmental change on polar bears will require monitoring at numerous spatiotemporal scales and across various levels of biological organization. In this dissertation I used and refined a variety of ecological monitoring tools that evaluated the effects of seasonal and longer-term unidirectional sea ice changes to various aspects of polar bear ecology. At a molecular level, I used urea to creatinine ratios in polar bear blood to show that an increased number of polar bears were in a physiological fasting state during spring captures in 2005-2006 compared to the mid-1980s. These changes corresponded to broad-scale changes in Arctic sea ice composition, which may have altered prey availability. I also used measurements of naturally occurring stable isotopes (δ13C, δ15N) in polar bear tissues to examine their diet, which included both lipid-rich blubber and the proteinaceous tissues of their marine mammal prey. Because the proportion of proteins and lipids consumed likely depended on prey type and size, it was necessary to consider metabolic routing of these macromolecules separately when using isotope mixing models to determine and monitor polar bear diet. I also monitored polar bear movement and migration behaviour at the population level. Specific landscape sea ice metrics corresponded to seasonal population migration patterns and fidelity to particular geographic regions. Trends in the timing of these seasonal population migration patterns were likely associated with climate-induced changes to sea ice dynamics. Finally, I examined migration behaviour in relation to local sea ice dynamics in individual polar bears and demonstrated a mechanistic understanding of the relationship between sea ice and polar bear migration patterns. / Ecology

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 98-107). Also available via the Internet.

The niche concept provides a tractable measure of the ecological roles and requirements of organisms, which can inform our understanding of the patterns of biodiversity, and subsequently, direct conservation policy. Although niche is most commonly considered for species, variation nested within lower hierarchies of biological organization (i.e., phenotypes, genotypes) also contributes to maintaining biodiversity. Herein I examine spatial and dietary niche variation among and within species in a consumer–resource system where resources and competition are structured by a heterogeneous environment. An underlying theme of this dissertation was developing research through a community-engaged approach that not only contributed to conceptual advancements in niche theory but also to applied conservation priorities. The marine archipelago of the central coast of British Columbia, Canada structures salmon (Oncorhynchus spp.) resources and the inter- and intraspecific competitive context for coastal grizzly (Ursus arctos) and black bears (Ursus americanus). This assembly of ursids represents nested levels of biological organization (i.e., species, phenotypes (white vs black-coated morphs of black bears) and genotypes (dominant homozygote black-coated black bears, heterozygote black-coated black bears, recessive homozygote white-coated ‘Spirit’ black bears)), which allows for investigation into niche variation across and within species. I investigated niche variation using a suite of non-invasive methods. Local and Traditional Ecological Knowledge (LEK/TEK) provided complementary information to genetic and stable isotope (13C and 15N) data from hair samples. First, I investigated changes in the spatial niche of coastal grizzly bears. By combining western scientific approaches with TEK/LEK interviews I found the range of coastal grizzly bears has expanded westward onto several coastal islands. The economic, cultural, and ecological impacts of this shift in spatial niche are not yet understood. Second, I tested hypotheses related to variation in the foraging niche of black bears in response to the competitive environment and salmon resource availability. I found that grizzly bear presence reduced the proportion of salmon in black bear diets by ~40%. I also found that salmon species diversity, and not biomass abundance, was positively correlated to salmon in black bear diets. This highlights the importance of resource diversity to consumers beyond the consideration of abundance. Third, I explored spatial niche patterns of Spirt bears in relation to protected areas. I found that landscape-level Spirit bear allele frequency and population estimates were lower than previously reported. Approximately ~50% of Spirit bear allele hotspots corresponded to protected areas. This finding suggests Spirit bears are rarer and less protected than previously assumed. Finally, I tested hypotheses related to niche variation between phenotype and genotypes of Spirit bear populations. I found both phenotypes and genotypes diverged in foraging niche, with Spirit bears and black-coated heterozygotes having elevated stable isotope signatures compared to black-coated homozygotes. This result supports the role of ‘multi-niche’ mechanisms in maintaining this rare polymorphism. Results from all chapters contributed to land- and marine-use stewardship efforts of collaborating First Nations. Collectively, this dissertation offers novel contributions towards understanding how niche variation at multiple levels of biological organization can contribute to conservation planning. / Graduate / 2020-04-04

The causes of natural mortality and disease in free ranging black bears, Ursus americanus, in California, Oregon, and Washington are poorly known. Life history components, such as scavenging and overlapping habitat with many species of carnivores, potentially expose bears to a wide range of infectious disease agents. To date, no disease has been identified that appears to greatly influence black bear population dynamics. The objectives of this study were to determine the prevalence rates of exposure to selected infectious disease agents in black bears at six study sites of California, Oregon, and Washington, and to assess if age, sex, study area, or year of sampling are related to the prevalence of specific diseases. One hundred and ninety nine black bear serum samples were collected between 1993 and 1997 and tested for selected viral and bacterial disease agents. Antibody prevalence was 0% for bluetongue virus, 12.6% (24/190) for Borrelia burdorferi (Lyme disease), 0% for Brucella spp., 0% for Dirofilaria immitis (heartworm), 4.8% (8/165) for canine distemper virus, 4.5% (9/198) for Ehrlichia equi, 0% for epizootic hemorrhagic disease virus, 9% (8/88) for Francisella tularensis (tularemia), 1.8% (3/165) for canine infectious hepatitis virus, 2.5% (5/198) for Trichinella spiralis, 45% (89/198) for Toxoplasma gondii and 5.5% (11/198) for Yersinia pestis (plague). Prevalence differences were observed among study sites. Lyme disease and plague antibodies were detected only in black bears from California and Oregon. E. equi antibody detection was highest from California bears. This is the first report of E. equi in the Ursidae family, and the first report of morbillivirus in black bears. These data do not support the relationship reported in other studies of rising prevalence rates with increased age of bears. The potential implications of diseases transmitted by translocated bears or re-introduced sympatric carnivores should be considered before management decisions are made. / Graduation date: 1999

Thesis (M.Sc.)--Acadia University, 2000. / Includes bibliographical references (leaves 123-128). Also available on the Internet via the World Wide Web.

Thesis (M.S.)--University of Idaho, 2007. / Includes bibliographical references. Also available electronically on the Internet.