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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.
151

American Black Bears (Ursus americanus) of the Paunsaugunt Plateau: Movements and Habitat Use

Dungan, Rebekah Adriana Castro 02 December 2019 (has links)
Concerns over human-bear conflict and questions about the ecology of Paunsaugunt Plateau's population of black bears (Ursus americanus) arose due to their visitation to popular recreation sites. Greater insight about bears and their habitat use provides a foundation for conflict mitigation and effective management decisions. Between 2014 and 2017, seventeen black bears (11 female, 6 male) were fitted with global positioning system (GPS) radio-collars so that we could track their locations, daily activity patterns, and ambient temperatures. By analyzing bear locations, we calculated annual and seasonal home ranges for 16 bears, including 25 den sites. Home ranges typically consisted of three dominant vegetation types, Utah juniper, ponderosa pine and Douglas fir. I used mixed effects models to better understand den site selection and found that slope (27.87 ± 2.03) was the most significant factor (p < 0.001). I also used mixed effects models to understand black bear selection of annual and seasonal home ranges. Predictor variables with the greatest effect (p < 0.001) were elevation (2419.99 ± 1.35) and aspect (138.44 ± 0.64), with coefficients of 1.128 and -1.483 respectively. Male annual home ranges (327.20 km2 ± 133.58 km2) were significantly larger (p = 0.035) than female home ranges (175.10 km2 ± 55.37 km2). However, annual home ranges for both sexes were larger than those during hyperphagia (p = 0.003) or mating (p = 0.004) seasonal home ranges, between which there was no difference (p = 0.451). Individual home ranges overlapped for most bears, consistent with their non-territorial nature. I found that bears avoided roads and lower elevations, while showing a preference for sloping terrain throughout the non-denning period. Paunsaugunt black bear home ranges are larger than any other black bear home ranges reported in literature. We determined weekly average distances and directions for all bears. For two bears, one male and one female, we determined daily averages and directions. Nine bears provided daily averages for 12 seasonal units across all four years. Activity patterns indicate the typical crepuscular pattern noted in normal bear populations that lack human habituation. Identifying areas core use areas and potential den sites is helpful to understanding black bear ecology and useful when making decisions about how to plan infrastructure and educate the public. This research indicates that Paunsaugunt black bears avoid human activity; however, we need continued research to help determine specific interactions between bears and anthropomorphic influences.
152

<strong>MOVEMENTS, HOME RANGES, AND HABITAT USE OF  JUVENILE GREEN TURTLES IN SANTA ELENA BAY, MATAPALITO BAY, AND LEONCILLOS BAY IN COSTA RICA</strong>

Fanqi Wu (16317180) 13 June 2023 (has links)
<p>This study monitored daily and seasonal locations of juvenile green turtles in three coastal bays of northwest Costa Rica, determining their home ranges and assessing their habitat use. My objective was to produce insights which might help future Pacific Ocean green turtle conservation efforts.</p> <p>I tracked 14 juvenile green turtles for 51-629 days using acoustic transmitters (VECOM v16) and 12 acoustic receivers (VECOM VR2Tx and VR2W) in 5 study area habitats: sandy areas, reef patches, macroalgae, rocky reefs, and mangroves. I divided these 14 turtles into large (equal to or larger than 65 cm CCL) and small (smaller than 65 cm CCL) size classes so I could highlight any changes as they grew toward adulthood. </p> <p>Both the large and small size turtles used habitats differently during the dry and rainy seasons. During the dry season, the large juveniles had a High Detection Rate (HDR) of 40% in the macroalgae area. During the rainy season, their HDR was 33% in the reef patch area. The small juveniles had their HDR in the reef patch area during both seasons: 33% in the dry season and 43% in the rainy season. The mean home range for the 14 turtles was 1.96 km²; their core use area was 0.19 km2. I saw no connection between body size and home range. The HDR findings suggest that juvenile green turtles preferred reef patches, rocky reefs, and macroalgae habitat types. The large juveniles prefer vegetation areas more as they grew; similar to that of adult green turtles. Some turtles moved between Matapalito Bay and Santa Elena Bay and along the coast to small bays east of Matapalito Bay. Travel speed varied between 0.23 km/h and 12.90 km/h with a mean of 1.57 km/h.  </p> <p>My findings highlight certain habitat areas preferred by Pacific juvenile green turtles. This can guide conservationists in identifying and protecting similar habitats in other inshore Pacific bays in Central America. By protecting habitat areas that are important for juvenile green turtles, this can help rebuild the green turtle population in the Pacific Ocean. </p>
153

Resource Selection, Home Range and Habitat Associations of the Southern Fox Squirrel (<i>Sciurus niger niger</i>) in the Piedmont and Coastal Plain of Virginia

Guill, Marissa Hahn 01 September 2023 (has links)
The southern fox squirrel (Sciurus niger niger) has the northernmost part of its range in Virginia. For the past 100 years, southern fox squirrels have been declining due to habitat fragmentation, cover type conversion, and fire suppression. Decrease in growing season burns, hardwood encroachment and forest mesophication have transformed pine hardwood woodlands and pine (Pinus spp.) savanna habitats that southern fox squirrels prefer to hardwood dominant habitats that eastern gray squirrels (Sciurus carolinenisis) prefer. These habitat changes have the potential to increase competition among the two species. The main objectives of my study were to investigate the general resource needs, occupancy, and home range of southern fox squirrels as well as the impact of resource partitioning and possible competition with eastern gray squirrels in the Piedmont and Coastal Plain of Virginia. I captured, radio collared and tracked four individuals at Big Woods Wildlife Management area and Piney Grove Complex using 95% and 50% kernel density estimate. I found an average male home range 173.49 ha (SE = 25.73, N = 2) and 40.62 ha (SE = 5.87, N = 2) and an average female home range of 28.51 ha (SE = 0.49, N = 2) and 4.71 ha (SE = 0.34, N = 2). I then identified the second and third order habitat selection in which my top models identified selection for pine savanna cover types (β = 2.095, SE = 0.158), increasing number of burns since 2019 (β =1.24, SE = 0.098), and decreased time between burns (β = -0.233, SE = 0.097). I used two-species occupancy modeling which reflected that gray squirrel occupancy increased with increasing time since last prescribed burn. However, southern fox squirrel occupancy, in the absence of gray squirrels, decreased with increasing time since last burn. My informed single-season occupancy model confirmed that southern fox squirrel occupancy decreased with time since the last burn. Presence in the absence of gray squirrels suggests that southern fox squirrels are selecting habitats on BWPGC with respect to both resource needs and competition with gray squirrel. Additionally, my level-of-effort (LOE) analysis indicated that 7 consecutive days of camera trapping without a southern fox squirrel detection would provide 90% confidence of the species' absence in areas burned 2 or more years prior to sampling in southeastern Virginia. Further management for southern fox squirrels in the future should focus on high rotational (short fire return interval) burns in areas of savanna as well as pine-hardwood mixed areas and hardwood-pine savanna ecotones. / Master of Science / The southern fox squirrel (Sciurus niger niger) is a subspecies of fox squirrel that ranges from southeastern Virginia down to northern Florida. All throughout its range in the Southeast, southern fox squirrel habitat has been fragmented from natural mixed pine-hardwood woodland forests to agriculture and high rotation pine plantations. Additionally, habitat has been further transformed by the lack of prescribed fire as a management tool on the landscape. This has in turn created sparse and fragmented local populations of southern fox squirrels as well as possible competition with gray squirrels. Further, the southern fox squirrel has not been studied in Virginia in over 20 years and management recommendations are lacking. I studied the resource needs, occupancy, home range and competition of southern fox squirrels in two physiographic regions of Virginia: the Coastal Plain and Piedmont regions. The Coastal Plain field site was Big Woods Wildlife Management Area and The Nature Conservancy's Piney Grove- both adjacent to each other. The Piedmont field site was Military Training Center Fort Barfoot. Here I utilized camera trapping, nest box monitoring, live trapping, and radio tracking to assess the resources they are utilizing in each area through home range analyses. I found that southern fox squirrels are selecting areas that have low fire return intervals and are located in pine savanna habitats. Therefore, fire should be prioritized as a management tool for southern fox squirrel habitat in pine savanna areas. I also used camera trapping data to identify the possible competition among gray and fox squirrels and fox squirrel detection through occupancy modeling. My findings reflected that there is apparent competition between southern fox squirrels and eastern gray squirrels and that southern fox squirrels are selecting heavily burned areas not only for their resource needs, but also because gray squirrels are absent. I concluded through my studies that the southern fox squirrel currently occupies southeastern Virginia, particularly in the Coastal Plain, however at low numbers. This could be due to suitable habitat on Big Woods/Piney Grove, but the surrounding habitat is of marginal quality. Further, in documenting southern fox squirrels, multi day camera surveys in mixed pine-hardwood woodland and pine savannas should be prioritized. Also, in aims to increase the presence of southern fox squirrels on the landscape, short rotation prescribed burning should be prioritized as well as additionally considering meditation among gray squirrel and fox squirrel competition.
154

Movements, relatedness and modeled genetic manipulation of white-tailed deer

Webb, Stephen Lance 11 December 2009 (has links)
White-tailed deer (Odocoileus virginianus) have been intensively studied across their range. However, many aspects of the white-tailed deer’s ecology have not been studied or are difficult to study. The advent of global positioning system (GPS) collar technology and molecular genetics techniques now allows researchers to collect fine-scale and cryptic phenomena. In addition, selective harvest of male white-tailed deer, based on antler size, has not been critically evaluated. Thus, development and use of quantitative genetics models will be useful for elucidating the effects of selective harvest on mean population antler size. I used GPS collar technology to further understand white-tailed deer movement ecology. First, I determined the efficacy and influence of a high-tensile electric fence (HTEF) on deer movements. The HTEF controlled deer movements when properly maintained and had little influence on deer spatial dynamics, making it a safe and cost-effective alternative to traditional fencing. Second, I studied fine-scale deer movements using GPS collars collecting locations every 15 minutes. Hourly deer movements were greatest in the morning and evening. Parturition and rut influenced movements of females and males, respectively whereas weather and moon phase had minimal influence on movements. Molecular genetics techniques are becoming more widespread and accessible, which may allow insight into the link between genetics and antler size. I found deer in 3 diverse populations from Mississippi, Oklahoma and Texas were relatively heterozygous and unrelated. Groups of deer with similar antler characteristics did not appear to be inbred or share common ancestors. In addition, there was not a strong link between individual multi-locus heterozygosity and antler points or score. Selective harvest has been implicated in causing negative evolutionary and biological responses in several ungulate species. To better determine how selective harvest (i.e., culling; the removal of deer with inferior antlers) affects white-tailed deer antler size, I used quantitative genetic models to simulate response of deer antlers to selection. In simulated controlled breeding situations response to selection was rapid, resulting in improvement in antler size. In simulated free-ranging populations response of antler size to selection was slow and only resulted in minimal increases in antler points after 20 years.
155

Spatial Ecology of Great Barracuda (Sphyraena barracuda) around Buck Island Reef National Monument, St. Croix, U.S.V.I.

Becker, Sarah L 13 July 2016 (has links) (PDF)
Marine protected areas (MPAs) are increasing in popularity as a tool to manage fish stocks through conservation of entire habitats and fish assemblages. Quantifying the habitat use, site fidelity, and movement patterns of marine species is vital to this method of marine spatial planning. The success of these protected areas requires that sufficient habitat is guarded against fishing pressure. For large animals, which often have correspondingly large home range areas, protecting an entire home range can be logistically challenging. For MPAs to successfully protect large top predator species, it is important to understand what areas of a home range are especially important, such as breeding and feeding grounds. New technologies, such as acoustic telemetry, have made it possible to track marine animal movements at finer spatial and temporal scales than previously possible, better illuminating these spatial use patterns. This study focused on the movement patterns of great barracuda (n=35), an ecologically important top predator, around Buck Island Reef National Monument, a no-take MPA in St. Croix, U.S.V.I. managed by the National Park Service. As developing standardized methods for acoustic telemetry is still a work in progress, the first half of this study focuses on determining appropriate tools for generating home range size estimates for great barracuda and analyzing ecological parameters driving these results. The second half of this study focused on the use of network analysis to look at spatial divisions within individual home ranges and to compare individual to population level spatial patterns, as well as to generate a relative estimate of population density within the park. Barracuda within the park demonstrated high site fidelity to individual territories, but at the population level they consistently used all habitats within the array. Core use areas within home ranges were evenly distributed throughout all habitats monitored by the acoustic array, although movement corridors were detected along high rugosity reef structures. Greater population densities within the park indicate that density dependent behaviors may be influencing habitat use within the park, and suggest that barracuda are contributing high levels of top down pressure through predation within the park boundaries.
156

Spatial Ecology of Bobcats (Lynx rufus) in the Appalachian Mountains of Western Virginia

McNitt, David C. 27 August 2019 (has links)
Despite the prevalent distribution of bobcats in western Virginia and the broader region of Appalachia, there is a paucity of information on their spatial ecology in this region. Due to the unique ecological conditions of Appalachia, and increasing public interest surrounding the role of bobcats as predators in the region, there is a need for local information on bobcat ecology. I utilized data from 20 GPS collared bobcats (14M, 6F) to investigate bobcat spatial ecology in the mountains of Western Virginia. Average resident male home range size was 33.9 ± 2.6 km^2, nearly 3 times larger than average resident female home range size (12.1 ± 2.4 km^2). Seasonal areas of use did not differ in size among seasons, but exhibited minor shifts in location and shape. Average male movement rates (232.3 ± 12.0 meters/hour) were 1.5 times greater than average female movement rates (154.4 ± 8.9 meters/hour). Male movement rates increased during the dispersal season and female movement rates increased during the denning/kitten-rearing season. Second order resource selection analysis indicates that bobcats of both sexes select home ranges at higher elevations than expected at random, and that selection varies between sexes and among seasons. Third order resource selection analysis indicates that bobcats select for locations near open canopy structure, and avoid forest interior. These findings build upon previous findings regarding bobcat diet and population dynamics to provide a comprehensive understanding of basic bobcat ecology in western Virginia, and will inform further research investigating predator/prey interactions. / Master of Science / Despite the prevalent distribution of bobcats in western Virginia and the broader region of Appalachia, there is a paucity of information on their spatial ecology in this region. Due to the unique ecological conditions of Appalachia, and increasing public interest surrounding the role of bobcats as predators in the region, there is a need for local information on bobcat ecology. I utilized data from 20 GPS collared bobcats (14M, 6F) to investigate bobcat spatial ecology in the mountains of Western Virginia. I found that male bobcats use more space than females, with home ranges nearly 3 times larger and movement rates 1.5 times higher. I found that home ranges do not expand or contract throughout the year, but do shift in shape slightly. I found that bobcats select home ranges at higher elevations, indicating that home ranges are predominantly located on ridges. I found that selection of home ranges differed between sexes and seasons, indicating that shifts in home range shape throughout the year reflect varying habitat selection. Within their home ranges, I found that bobcats select for areas of open canopy resulting from fields, fire, and timber harvest; and avoid areas of forest interior. These findings build upon previous findings regarding bobcat diet and population dynamics to provide a comprehensive understanding of basic bobcat ecology in western Virginia, and will inform further research investigating predator/prey interactions.
157

Ecology, Habitat Use, and Conservation of Asiatic Black Bears in the Min Mountains of Sichuan Province, China

Trent, Jewel Andrew 13 July 2010 (has links)
This project was initiated in an attempt to address the paucity of data on Asiatic black bears (Ursus thibetanus) in Mainland China. Field work was carried out from May 2004 – August 2006 within the Tangjiahe National Nature Reserve in northwestern Sichuan Province, China. Initial methodology relied on trapping and GPS radio-collaring bears, but due to extreme difficulty with capturing a sufficient sample size, I expanded the study to include reproduction, feeding analysis from scats and sign, and occupancy modeling from sign surveys. I documented the home ranges of an adult female (100% MCP = 107.5km2, n=470 locations) and a sub-adult female (100%MCP = 5.9km2, n=36 locations) Asiatic black bear. I also documented two birthing occasions with a total of four male cubs produced and eight bear den sites. I collected feeding data from 131 scat samples and 200 bear sign transects resulting in 50 identified food items consumed by Asiatic black bears. I also employed the program PRESENCE to analyze occupancy data using both a standard grid repeated sampling technique and an innovative technique of aging bear sign along strip transect surveys to represent repeated bear occupancy over time. Conservation protection patrolling and soft mast were shown to be the most important factors determining the occupancy of an area by Asiatic black bears in Tangjiahe Nature Reserve, Sichuan Province, China. / Master of Science
158

Trade-offs between the risks of predation and starvation in subtropical granivorous finches

Brandt, Miriam J. January 2007 (has links)
Animal community structures, life histories and individual foraging behaviour are all an outcome of a trade-off between competition for resources (and thus the risk of starvation) and survival (and thus the risk of predation). The relative importance of these factors however, differs between ecosystems, and especially when comparing temperate to tropical ones, we usually find marked differences. The seasonality of tropical ecosystems is much reduced compared to temperate ones, and weather conditions are less extreme. Accordingly tropical systems are characterised by higher species diversity, and different life history traits have been found between temperate and tropical birds. However, how the different environmental factors interact, and how predation and starvation risk vary to cause these differences still remains largely unknown. We studied the feeding behaviour of several granivorous Estrildid finches in scrub savannah habitat in central Nigeria to test how they respond to varying degrees of starvation and predation risk. During field observations and aviary experiments we investigated whether there is seasonal variation in the birds’ foraging behaviour correlating with the abundance of grass seeds and tested how they respond to different group sizes and differing distances from cover (representing a difference in predation risk). Further we also carried out field observation on the natural feeding behaviour of several closely related sympartic Estrildid finches to investigate inter-specific and seasonal differences in competition and microhabitat choice to see if this could explain their coexistence. Finally we studied habitat choice, movement behaviour and breeding biology of the potentially threatened endemic Rock Firefinch (Lagonosticta sanguinodorsalis) between the wet and the dry season via radio-tracking to establish its habitat requirements and gain the first information in its life history traits and population trends. We found little seasonal variation in the species’ foraging behaviour, and parameters that varied did not do so in a consistent manner. Thus, we found little evidence for a seasonal change in the risk of starvation. However, the abundance of several bird species varied widely between seasons and species leaving during periods of food shortage might have released competition for remaining resources. Birds did not show a strong response in their feeding behaviour with respect to cover in either intake rate or timing of feeding. However, intake rate increased with group size, which we believe to be due to scramble competition rather than risk dilution. We therefore conclude that predation did not shape the foraging behaviour of tropical granivorous passerines as markedly as that of temperate ones. Rock Firefinches were found to breed between the late rainy and the early dry season. They selected inselberg habitat, where most nests were found between rocky boulders. During the dry season, when water sources in inselberg habitat had dried out, they had to fly distances of up to 700 m to the gallery forest to get water and this led to the inclusion of more scrub savannah and gallery forest within their home ranges. Daily egg survival was 0.89 ± 0.03 calculated after the Mayfield analysis and most failing nests were depredated probably mainly by lizards. We suggest that in addition to nest predation, water availability might limit breeding time and thus reproductive output of Rock Firefinches. Predation risk did not seem to be of high importance in shaping the birds’ feeding behaviour because there was no seasonal variation in the risk of starvation. We found some suggestive evidence that competition might be important and it is likely that bird populations constantly stay close to carrying capacity. In contrast to temperate regions the need to conserve water might be of higher importance in shaping the birds’ feeding behaviour. High adult survival rates might be due to reduced seasonality in the risk of starvation thereby leading to reduced predation risk on adult birds. High nest predation might also be of higher importance in shaping the life history traits of tropical passerines, but at present this suggestion remains speculative. The results fit into the general framework that there is a trade-off between starvation and predation risk, and in the absence of starvation risk for some species in tropical areas, predation risk is also relatively unimportant.
159

Changes in adult female white rhino seasonal home ranges in relation to variation in food quality and availability.

Hebbelmann, Lisa. January 2013 (has links)
As the dry season progresses across southern Africa, the availability and quality of food declines for large herbivores. Female white rhinos compensate for these declines by expanding and/or shifting their home ranges. These changes may be to incorporate habitat types that contain high quality food or quite simply more food. To determine the factors that drive these seasonal changes in home ranges, I focused on dry season changes in the availability and quality of grass in habitats utilised by white rhinos in the Ithala Game Reserve, South Africa. I expected that if food quality was the main driver, white rhinos would follow optimal foraging principles and incorporate habitat types with the highest nutritional quality into their dry season home ranges. Alternatively, due to their large body size (>1000 kg) and thus ability to survive on low quality food, they may rather incorporate habitat types with high food availability. In contrast to previous studies, I found that during the dry season female white rhinos did not increase the size of their home ranges, but rather shifted their home range boundaries. This resulted in individuals increasing the amount of Bushveld and decreasing the amount of Wooded Grasslands within their dry season home ranges. When I explored the different factors that could explain these patterns, I found that changes in the crude protein content of grass was the key factor driving the incorporation and exclusion of habitat types in the home ranges. During the dry season, white rhinos incorporated the habitat that had the smallest seasonal reduction in crude protein content, while excluding the one with the largest decrease in crude protein. As a result, my results suggest that the search for high quality best explains the seasonal home range shifts of female white rhinos in the Ithala Game Reserve. / Thesis (M.Sc.Ecology)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
160

Comparative Biology of Three Species of Costa Rican Haeterini

Alexander, Laura 16 May 2014 (has links)
Documenting life history characteristics of populations, especially of herbivorous insects such as butterflies, is fundamental to the ecological study of tropical rainforests. However, we know relatively little about tropical forest butterflies. Here, I combine information gathered using the mark-release-recapture (MRR) approach with manipulative and observational experiments in a natural environment to explore aspects of the population biology of three closely-related species of Costa Rican fruit-feeding understory butterflies (Cithaerias pireta, Dulcedo polita, and Pierella helvina), specifically: vertical stratification, attraction to and persistence in fruit-baited traps, relative abundance and distribution, movement patterns, probabilities of recapture and daily survival, and factors that affect those probabilities. Among the three focal species there were differences in capturability, recapturability, spatial distribution, and degree of vertical stratification. Males appear to fly within smaller home ranges than females, and P. helvina can traverse the entire forest reserve in a single day. These findings have implications for the genetic diversity of these populations and for the risk of local extinction in the face of changing ecological conditions.

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