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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.
1

Nesting habitat and diet studies of sandhill cranes (Grus canadensis) from the central and north coast of British Columbia

Roessingh, Krista 24 August 2012 (has links)
The purpose of this study was to document the occurrence, habitat, and diet of sandhill cranes that breed in coastal British Columbia, a population believed to belong to the subspecies rowani. Specific objectives were to: 1) locate cranes and their nests in selected coastal areas of the central and north coasts (5138’N, 12805’W - 5400’N, 13037’W) and foster observer expertise in conducting aerial crane surveys; 2) describe sandhill crane nest habitat using a range of stand- and site-level characteristics; and, 3) identify diet content of breeding cranes from faecal samples. Helicopter surveys were conducted within 1.5 km of the coastline during May 2007 and 2008. Twenty nest sites were visited in 2008 to collect data on nest habitat characteristics. Satellite imagery was used to measure stand-level and landscape features for 29 nests. Faecal samples were collected at 6 nest and roost sites. During the 2008 survey, 104 cranes and 19 nests were counted over a 430 km2 area (average survey effort = 2.0 km2/min.). Crane nests were located in bog habitat, while cranes frequented bogs, shorelines, and marshes. Nests were in bog pools under 0.5 ha in size with the exception of one that occured in a 1.2 ha beaver-dammed pond (median = 0.10 ha, inter-quartile range (IQR) = 0.037 – 0.17 ha, n = 29), and had median water depth of 56 cm around nest islets (IQR = 49 – 77 cm, n = 21). Bog pools were in forest or woodland bog openings with median distance from the pool edge to the nearest treeline of 46 m (IQR – 24 – 160 m, n = 25) and median forest buffer width of 150 m (IQR = 93 – 260 m, n = 25). Forested habitat may serve as a corridor for cranes with pre-fledged young connecting bog nest and roost sites with shoreline foraging areas. Median distance from nest to shoreline was 400 m (IQR = 200 – 500 m, n = 28). Food items characteristic of faecal samples (n = 138) included mussel (Mytilus edulis), periwinkle (Littorina littorea) and limpet shells, insects, sedge (Carex spp.) and crowberry (Empetrum nigrum), plant remains, and crab remains. Changes in the probability of observing periwinkle and limpet in samples were observed between sites, while the frequency of occurrence of insects differed between time periods and that of sedge, crowberry, and mussels differed between time periods and sites. Sandhill cranes were sparsely distributed on inner and outer coastal islands with bog nesting habitat and sheltered intertidal foraging habitat. / Graduate
2

Estimating Distribution and Abundance of Rio Grande Wild Turkeys in South Texas

Caveny, Robert J. 2009 August 1900 (has links)
Sustainable management of wildlife populations relies on accurate estimates of population size as harvest recommendations are dependent on estimates of sustainable surplus. Techniques for surveying wild turkey populations in Texas are constrained by land access issues, requiring that new methods be developed for population monitoring. I evaluated a combined approach using patch-occupancy modeling at broad spatial scales and intensive double observer roost surveys at local scales to estimate Rio Grande wild turkey (Meleagris gallapavo intermedia) distribution and abundance. I flew replicated aerial surveys during 2007 and 2008 to evaluate distribution of Rio Grande wild turkeys in the south Texas Coastal Sand Plains. I used a double observer approach to estimate local scale abundance. I used a single observer approach to estimate temporal variation in roost use. Detection probabilities from aerial surveys ranged between 0.24 (SE = 0.031) and 0.30 (SE = 0.083). Spatial parameters that influenced distribution of wild turkeys included size of suitable roosting habitat patches and distance to the nearest suitable roosting habitat. I conducted 100 inter-patch double observer roost counts, with counts ranging between 0 to 183 individuals. Average detection probabilities for observers were ~0.90. Roost level occupancy was ~0.84 with detection probabilities between 0.69 (SE = 0.107) and 0.79 (SE = 0.091). Based on my results, aerial surveys combined with local abundance estimation may be one viable alternative to monitor turkey populations over large spatial scales, by reducing overall survey effort without loss of estimated precision.
3

The Population ecology of wild horses in the Australian Alps

Walter, Michelle, n/a January 2002 (has links)
In this thesis I examine the population ecology of wild horses (Equus caballus) in the Australian Alps. Wild horses were first introduced into the Alps over 150 years ago. Paradoxically, they are a feral animal impacting on the environment, but are also a cultural icon. Managing wild horse populations is contentious and needs to be founded on knowledge of their population ecology. This is the first study of its kind in the Australian Alps and therefore has a broad focus. Four general areas were addressed: distribution, estimation of abundance and density, population dynamics and the influence of brumby-running. The study was conducted between 1999 and 2002 inclusive in the Australian Alps national parks, which form a contiguous protected area in south-eastern Australia from the Australian Capital Territory (ACT) in the north, through New South Wales (NSW) and into Victoria in the south. The current distribution of wild horses in the Australian Alps national parks is patchy. There are five major discrete populations in NSW and Victoria with the northern most population in Kosciuszko National Park (NSW) bordering on the ACT. A review of published material and oral history reveals historic influences on distribution. The presence of each population is associated with introductions by people. The distribution of some populations expanded after introductions and many have fluctuated over time. Distributions have been contained or reduced through control by people, natural events such as snow and drought and by geographical barriers. Park managers eliminated a population of wild horses in the ACT in the 1980s. Distributions have expanded in areas without active management (notably northern Kosciuszko National Park) and are likely to continue expanding under a policy of no management. In February and March 2001, abundance and density of wild horses were estimated by helicopter aerial survey in areas where the mapping showed horses to occur. This was the first time that these parameters have been estimated empirically. I compared three different aerial survey techniques (strip, mark-recapture and line transect) based on relative accuracy and precision and found that line transect analysis gave the highest, most precise estimate. Given that aerial surveys usually underestimate abundance, this method was also likely to be the most accurate. Mark-recapture over a 50m wide strip gave a similar result but lacked precision. Strip and mark-recapture techniques performed poorly over 200m strips because animals were missed. Numbers observed dropped off dramatically beyond the 50m strip. Line transect analysis (for both observers combined) gave an estimate of 5010 (+/- 1408SE) horses while mark recapture over 50 metres gave an estimate of 4915 (+/-2733SE). These estimates correspond to a density of 1.8 horses km-2 over the area surveyed (2789km2). The results suggest that aerial surveys of large mammals using a wide strip width (200m) and mark recapture analysis may seriously underestimate population density. The population dynamics and demography of wild horses were estimated at three sites, Big Boggy, Cowombat and Currango, every spring and autumn over 3 years. The sites were spread widely across the Alps with the aim of obtaining a broad understanding of population dynamics. The survey used Pollock�s robust design and natural markings were used to identify individuals. There was a seasonal spring peak in population size at Big Boggy with no clear seasonal trend at the other two sites. Mean wild horse densities determined at Big Boggy (2.01km-2) and Currango (2.13km-2) were not significantly (p<0.5) different to the density calculated in the aerial survey, whereas density was significantly higher at Cowombat (6.4 km-2). Census techniques were of limited use in estimating annual population growth rate because of low precision. Demographic analysis showed that none of the populations were increasing at the maximum intrinsic rate (l = 1.2), and the Big Boggy and Cowombat populations may be stable (l = 1.0/yr). There was an apparent trend of food limitation across the sites. Body condition was positively related (p<0.01) to pasture biomass. The Currango population was increasing (l = 0.09) associated with higher recruitment, body condition and pasture biomass than in the other two populations studied. The Cowombat population had the lowest annual finite rate of increase (l = 1.03), and horses at this site were in the poorest condition and pasture biomass was lowest. The Big Boggy population was intermediate between the two. Annual adult survival was constant in all populations at 0.91. Survival in the first three years of life was more variable with the average at each site ranging from 0.63/yr to 0.76/yr. An average of 0.26 female foals was born per adult female per year. Sensitivity analysis showed that population growth rate is most sensitive to changes in adult survival, followed by fecundity and then survival in the first three years of life. The dynamics observed at each site was representative of the demography of wild horses in other parts of the world and is typical for large mammalian herbivores. Brumby-running is a form of harvesting that is currently being used to control wild horses in the Alpine National Park (Victoria) and is soon to be trialled in Kosciuszko National Park (NSW). The effectiveness of brumby-running has not been assessed prior to this study. Data collected by the Alpine Brumby Management Association and predictive modelling were used to examine the influence of brumby-running on the wild horse population in Alpine National Park. Brumby-runners remove about 200 horses per year with a preference for young animals and adult females. More horses are caught in autumn (61/yr) and least in summer (30/yr) (p<0.05). Brumby-runners do not appear (p>0.05) to target horses in poor condition. One skilled brumby-runner caught an average of 1.16 horses/day, while his companions caught an average of 0.55 horses/day. Brumby-runners show behaviour analogous to social carnivores. Predictive modelling suggests that brumby-runners could suppress the population of wild horses in Alpine National Park similar to the effects of predators, or human harvesting of other large mammals. Selecting young animals in the harvest reduces the impact of harvesting on the population compared to unselective harvesting, while selecting adult females increases the predicted impact. There are several management recommendations based on the findings of this thesis that address concerns for both environmental impact and the cultural value of wild horses. The distribution of wild horses should not be allowed to expand further, and the size of the wild horse population should be prevented from increasing further. Other management recommendations that are more complex involve reducing some populations so that the level of environmental impact they are causing is acceptable. This requires a definition of �acceptable impact.� Finally managers should consider eradicating smaller populations.
4

Design, Evaluation, and Applications of an Aerial Survey to Estimate Abundance of Wintering Waterfowl in Mississippi

Pearse, Aaron Todd 05 May 2007 (has links)
Estimates of abundance are critical to manage and conserve waterfowl and their habitats. Most surveys of wintering waterfowl do not use probability sampling; therefore, development of more rigorous methods is needed. In response, I designed and evaluated an aerial transect survey to estimate abundance of wintering ducks in western Mississippi during winters 2002?2004. I designed a probability-based survey using stratified random and unequal probability sampling of fixed-width transects. To correct for visibility bias inherent in aerial surveys, I conducted an experiment to model bias and incorporated correction factors into estimation procedures to produce adjusted estimates. Bias-corrected estimates were most accurate. Precision of abundance estimates of total ducks met a priori goals (CV ≤ 15%) in 10 of 14 surveys. Based on a simulation study, the implemented survey design provided the most precise estimates, yet certain refinements remained possible. I also illustrated potential applications of survey results in the context of conservation and management of wintering waterfowl populations and habitats. I described patterns of abundance within and among winters, including a comparison with surveys conducted during winters 1988?1990 that revealed mallard abundance decreased 65% from the late 1980s. I developed a method to illustrate population abundance spatially for scientific and public education. I attempted to explain temporal variation in abundance estimates relative to variables potentially representing hypotheses explaining regional distributions of ducks. I concluded the data provided stronger support for factors related to energy conservation by ducks than factors related to energy acquisition. Finally, I determined associations between duck distributions and habitat and landscape features in accordance with the habitat-complex conceptual model. Landscapes with greater interspersion and diversity of wetlands attracted increased numbers of ducks, a though other factors such as wetland area also were important. I concluded that this study advanced methodologies to survey wintering waterfowl. Although improvements were warranted, I recommend this survey design for continued monitoring of wintering ducks in western Mississippi. Furthermore, I suggest habitat management on public and private lands should include complexes of seasonally flooded cropland, moist-soil, forested, and permanent wetlands to potentially increase wintering duck numbers in western Mississippi.
5

The Iron Age archaeology of the upper Thames and north Oxfordshire region, with especial reference to the eastern Cotswolds

Lang, Alexander Thomas Orr January 2009 (has links)
This thesis considers the development of settlement landscapes in the Iron Age across two adjacent regions, the upland eastern Cotswolds and lowland upper Thames valley. Previous studies have focused on the differences in settlement form, economic practice and social development and therefore the possible dichotomy of heartland and hinterland landscapes. It is clear, however, that this is due to an imbalance of research brought about as a result of the natural landscape, interests of antiquarians and archaeologists and modern settlement focus and development. A new dataset of cropmark and geophysical survey material is presented as a way of redressing the imbalance. The focus within this study on banjo enclosures also provides an opportunity to analyse what remains a relatively enigmatic and understudied site-type that appeared during the Middle and Late Iron Age. The results illustrated and discussed here provide the chance to outline new narratives that take into account both practical and non-functional interpretations. From this, more is elucidated regarding these sites within the context of Middle and Late Iron Age settlement landscape developments. By integrating this new dataset within the wider context of the upper Thames and immediate environs a number of further and more general questions have been raised. These focus on the chronology of settlement development, the appearance and growth of exchange networks and the changing significance of open and enclosed settlements throughout the period. Differences have been used in the past to symbolise alternative social systems apparent across two settlement landscapes. However, as a result of the evidence presented here these perceptions are no longer viable as an interpretive framework. Instead, aspects of chronological development, settlement space and sphere of influence and interaction are discussed in relation to the evidence from Midlands and central southern Britain.
6

Differential Use of Two Warm-Water Effluents by the Florida Manatee (Trichechus manatus latirostris) and Temporal Distributions throughout Broward County, Florida

Eldredge, Laura F 27 July 2017 (has links)
The threatened Florida manatee (Trichechus manatus latirostris) migrates seasonally to warm-water refugia throughout the state of Florida due to metabolic requirements from low thermal conductance. Broward County’s two power plant refugia, Port Everglades (PEP) and Lauderdale (LPP), are known heavily-utilized aggregation sites for the Atlantic sub-population. Broward County collected relative abundance counts via aerial surveys from 2004–2013 siting 31,418 manatees during 169 surveys within 18 defined waterway zones. Counts during manatee wintering seasons were significantly different from January 2005-March 2008 and November 2008-March 2013, likely related to flight path and frequency standardization. Mean percentage of adults (90.12%) to calves (9.88%) demonstrates a higher usage by cow-calf pairs than other aggregation sites. Counts of manatees traveling south to Miami-Dade County comprised only 0.83% of all aerial counts, contrary to the theory of the extensive usage of Biscayne Bay foraging grounds. The LPP zone had 57.21% of all manatees with Port Everglades Inlet zone accounting for 23.88% and the South Fork New River zone with 5.95%. This study provided a baseline for pre-construction distributions prior to Port Everglades plant reenergization. With PEP construction now finished and LPP planned for reenergization in the next 10 years, monitoring data studies be compared to these baseline data to better assess the impact of the disruption of Broward County’s main refugia sources.
7

Visualizing and Modeling Mining-Induced Surface Subsidence

Platt, Marcor Gibbons 13 July 2009 (has links) (PDF)
Ground subsidence due to underground coal mining is a complex, narrowly-understood phenomenon. Due to the complicated physical processes involved and the lack of a complete knowledge of the characteristics of overlying strata, the reliability of current prediction techniques varies widely. Furthermore, the accuracy of any given prediction technique is largely dependent upon the accuracy of field measurements and surveys which provide input data for the technique. A valuable resource available for predicting and modeling subsidence is aerial survey technology. This technology produces yearly datasets with a high density of survey points. The following study introduces a method wherein these survey points are converted into elevation plots and subsidence plots using GIS. This study also presents a method, titled the Type-Xi Integration method (TXI method), which improves upon a previous subsidence prediction technique. This method differs from the previous technique in that it incorporates accurate surface topography and considers irregular mine geometry, as well as seam thickness and overburden variations in its predictions. The TXI method also involves comparing predicted subsidence directly to measured subsidence from subsidence plots. In summary, this study illustrates a method of combining data from aerial survey points and mine geometry with subsidence models in order to improve the accuracy of the models.

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