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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.
131

Longitudinal distribution and summer diurnal microhabitat use of California Red-Legged Frogs (Rana draytonii) in coastal Waddell Creek

Keung, Neil C. 04 September 2015 (has links)
<p> Habitat use by federally threatened California Red-Legged Frogs (CRLF; <i>Rana draytonii</i>) is incompletely understood. I captured, PIT-tagged, and radio-tracked CRLFs (n = 20) at Waddell Creek, Santa Cruz County, from July&ndash;December 2012. Limited tracking for movements was also conducted in 2013. Frogs were clumped in deep, complex habitats along the stream within 2 km of breeding ponds near the stream mouth, but most adults were concentrated in the lagoon. Marked and tracked frogs had very small summer home ranges, and most returned to the same home range after breeding. Frogs tended to use good aquatic (e.g., wood, undercut banks, dense willows) and bank cover (e.g., ground vegetation, wood) at all times but used open habitats more at night than during the day. Visual night surveys were biased against cryptic frogs compared to radio-tracking results. Early fall rains increased upland habitat use, but later heavy winter rains were needed to trigger migration to breeding sites and subsequent breeding. Site-specific studies using radio-tracking are needed to design protections for breeding, migration, and nonbreeding habitats.</p>
132

Seasonal patterns of gonadal development and condition index of Dendostrea sandvicensis

Garriques, Daren 11 February 2014 (has links)
<p> Very little information is available on the Hawaiian Oyster <i> Dendostrea sandvicensis</i> in regards to its biology and physiology. Efforts were made to better understand the active reproductive season of this oyster by studying the population located in He'eia fish pond in Kaneohe Bay, O`ahu. This study focused on the condition index (CI) and gonadal developmental stage trends, measured from monthly oyster tissue samples from January to December 2009. The relationship between CI and temperature was examined. Results suggest CI is not related to temperature. Further analysis defined a positive correlation for CI and temperature during summer but not in winter. Ranges in CI values were higher in summer than in winter. <i>D. sandvicensis </i> experience a tropical reproductive cycle, as trends related to the gonadal stage indicate. January to March is dominated by maturing gonads. From April to October there is a rise and then steady decline of empty gonads indicating an active reproduction season. From November to December a rise in mature gonads indicate readiness for reproduction and recovery. Empty gonads are present through out the year indicating reproduction happens throughout the year, and peaks in beginning of summer.</p>
133

The Effect of Land Use and Climate on Malaria Risk in the Amazon Region

Valle, Denis January 2013 (has links)
<p>The goal of this thesis is to study the relationship between climate and land use / land cover (LULC) on malaria risk in the Amazon region. Despite the large public policy implications, current literature provides contradictory evidence regarding how LULC affects malaria risk. Furthermore, little is known regarding the public health impacts of the predicted drying of the Amazon. In this thesis, we rely on mosquito and malaria incidence/prevalence data from multiple sources, both from the Brazilian and Peruvian Amazon, and we develop novel methodology to integrate multiple datasets and infer malaria risk factors. </p><p>The first chapter describes a novel method to combine data from different Plasmodium detection methods (i.e., polymerase chain reaction (PCR) and microscopy) and sampling schemes (i.e., aggressive active case detection and passive case detection). Using this method and detailed data on malaria prevalence, we find that proximity to forest, as well as participation on forest activities, greatly enhance malaria risk. Furthermore, our results suggest that asymptomatic Plasmodium carriers are more likely to be individuals that have recently arrived in the region and that live in regions with high forest cover. </p><p>The second chapter describes large scale patterns regarding LULC, climate, and malaria incidence. To this end, we rely on a unique dataset collected by the Brazilian government surveillance system over ~4 years, spanning ~4.5 million km2 and 1,300,000 malaria cases. This analysis indicates that malaria incidence is substantially higher in areas with higher forest cover, whereas deforestation rate (the often cited culprit of malaria in the region) is not significantly associated with malaria. We also find that a drier climate may enhance malaria risk in the Brazilian Amazon region. We then employ a statistical model and a LULC simulation model to predict that malaria risk may be substantially higher in a governance (GOV) scenario versus a business-as-usual (BAU) scenario, a direct consequence of the averted deforestation under the GOV scenario.</p><p>In the third chapter, we discuss how current methodology to characterize mosquito breeding habitat may be improved when the goal is to guide larva control interventions and identify areas with higher disease risk. To accomplish these goals, we contend that it is critical for researchers to understand the spatial and temporal distribution of water bodies. We use simulations and Anopheles darlingi larva data to illustrate how inference might be misleading when the distribution of water bodies is ignored.</p><p>Finally, the fourth chapter re-examines results from a key study conducted in the Peruvian Amazon, which has been the basis for the widespread notion that malaria risk increases in deforested areas. Differently from the original studies, I integrate mosquito larva and mosquito biting rate from multiple vector species with malaria prevalence data, to determine how LULC and climate affect malaria risk. I find that A. darlingi larva presence and biting rate indeed increase in deforested areas, agreeing with the original published results. However, we find that malaria prevalence is not associated with A. darlingi biting rate whereas it tends to be positively associated with A. rangeli biting rate. We hypothesize that there is a mismatch between location and time of the day at which individuals are more exposed to infections and our predictions of mosquito biting rate, which are based on household locations and a 18 - 24:00 period. If this hypothesis is correct, any association between malaria prevalence and the mosquito biting rate is likely to be spurious. Although our analysis is not conclusive because of limitations in the malaria prevalence dataset, our results suggest that inference on malaria risk based solely on a single vector species might be misleading. In particular, the relationship between deforestation and malaria risk will critically depend on how exposure changes as a function of human behavior and on the competence of the different vector species.</p><p>Throughout this thesis, a major thrust has been to employ statistical models carefully tailored to the problems at hand, with the overarching goal of generating more reliable inference. To this end, I have created parsimonious models (e.g., using multiple shrinkage priors or using a reversible jump algorithm) which properly accommodate data idiosyncrasies (e.g., zero inflation and over-dispersion) and use, when possible, data from multiple sources.</p> / Dissertation
134

Modelling the spatial distribution of mammals

South, Andrew Brian January 1999 (has links)
In this thesis I outline the different processes, operating at different scales, that influence the spatial distribution of mammals and review modelling approaches that have been used to represent these processes. I investigate the application of a selection of modelling approaches operating at different scales. A model based on the energetics and movements of individual foragers was developed to investigate population spacing patterns and applied to the red squirrel. At high food densities, small, similarly sized, non overlapping ranges were generated, whereas at low food densities ranges were larger, more overlapping and more variable in size. The model is a first step towards investigating the spacing patterns of ranging mammals. A model representing the positioning of dens was applied to predict the distribution of badger main setts. The model determined how many setts could be placed in suitable habitats while maintaining a pre-defined, minimum inter-sett distance. The representation of badger spacing behaviour and the utility of the approach is discussed. At a larger scale, a model based upon births and deaths within habitat patches and an explicit representation of dispersal between patches was used to assess plans to reintroduce the beaver. It predicted little or no population spread, in contrast to the application of a generic population viability analysis package that predicted rapid population spread. A difference in the representation of dispersal was identified as the most likely cause of the disparity. A general model based on these approaches was developed to investigate the interaction between dispersal and demographic processesing spatially explicit population models. The future of models to predict the spatial distribution of mammals is discussed in relation to issues of scale, management applications and modelling philosophies.
135

Conservation Biology of Bottlenose Dolphins(Tursiops Sp.) in Perth Metropolitan Waters

hugh.finn@bigpond.com, Hugh Colin Finn January 2005 (has links)
This thesis examines two potential conservation problems for a residential sub-population of ~75 bottlenose dolphins (Tursiops sp.) in Cockburn Sound, a small embayment within the southern metropolitan waters of Perth, Western Australia: (1) human-induced habitat change and (2) illegal feeding (i.e. unregulated provisioning) of dolphins. The work is important because Cockburn Sound is the most intensively utilised marine environment in Western Australia and industrial, commercial, and recreational uses of the area will intensify in coming decades. These considerations, coupled with the demographic and ecological vulnerability of residential populations of small cetaceans, suggested a risk of population decline without a more informed scientific basis for management. This study (2000 – 2003) complemented an earlier study of the Cockburn Sound dolphins (1993 – 1997) to provide a decade-long longitudinal study of the population. The original contributions of this study relate to: (a) the foraging ecology of dolphins;(b) the effects and mechanisms of human-dolphin interaction, particularly interactions based on unregulated provisioning; and (c) an integration of previous research and other information. Studies of the foraging ecology of dolphins within Cockburn Sound were undertaken between 2000-2 to determine the areas used by dolphins and their feeding behaviours so that the implications of human-induced habitat change could be assessed. These studies used belt transect sampling and event-specific sampling of foraging aggregations of dolphins to quantify the foraging habitat use of dolphins within the Sound and to characterise spatial and temporal patterns in aggregations of foraging dolphins. The results showed that the density of foraging dolphins varied significantly across habitats and that foraging aggregations consistently occur in an area known as the Kwinana Shelf during the austral autumn-spring period. The studies also suggested that the foraging ecology of dolphins in Cockburn Sound reflects the consistent utilisation of both: (a) low-density prey species (i.e. individual or weakly-schooling prey) and (b) high-density prey species (i.e. schooling species such as forage fish). These findings indicate that ecosystem-based conservations of the population should consider the conservation requirements of dolphin prey species and the ecological integrity of key foraging habitats like the Kwinana Shelf. Human-dolphin interactions based on the illegal feeding of dolphins in Cockburn Sound escalated between 1993 and 2003. By 2003, a total of 14 individuals exhibited behaviours indicative of conditioning to human interaction by food reinforcement, including some individuals that engaged in provisioning interactions on a chronic (i.e. long-term) basis. Observations of the effects of unregulated provisioning indicated that: (a) provisioned dolphins sustained increased higher rates of human-induced injury than non-provisioned dolphins and (b) provisioning was associated with substantial and enduring behavioural changes including changes in ranging and association patterns. Other observations of human-induced injury in Cockburn Sound included seven instances of calf entanglement. These findings indicate that the effects of illegal feeding and other forms of direct human-dolphin interaction (e.g. entanglement) could achieve biological significance for the population. The possible contribution of (a) human influences, (b) social learning, and (c) behavioural propensities (e.g. age and sex) on the acquisition of an attraction response to human provisioning was examined through logistic regression analysis using age, sex, use of high-boat density areas, and the number of close associates that were previously provisioned as predictor variables and the acquisition of an attraction response as the dependent variable. This analysis was supplemented by behavioural observations of interactions between provisioned and naïve individuals during provisioning interactions. The results supported three findings: (1) a relatively high level of exposure to human provisioners was a significant predictor for the acquisition of an attraction response by dolphins; (2) social learning contributed to the acquisition of an attraction response in those individuals that more frequently utilised high-boat density areas; and (3) the potential contribution of behavioural propensities relating to age and sex was uncertain. These conclusions suggest that the acquisition of an attraction response to human provisioning can best be understood as the outcome of a complex of interacting factors. The findings also indicate: (a) the management value of individual-specific and longitudinal data for the management of harmful human-wildlife interactions and (b) the potential for social learning to contribute to the development and persistence of these interactions. The findings of this study indicate that population decline in Cockburn Sound could be induced by: (1) a reduction in the Sound’s environmental carrying capacity or (2) mortality, injury, and behavioural changes resulting from interactions with humans. The potential for such a decline and evidence demonstrating the harmful effects of human activities on dolphins supports the application of preventative approach to the management of illegal feeding and entanglement and a precautionary approach to environmental impact assessments of proposed developments. Mitigation of direct human-dolphins like illegal feeding requires an enforcement and education program to encourage more responsible human attitudes towards interactions with dolphins. Research on the ecology and composition of finfish assemblages and the trophic structure of the Kwinana shelf would assist efforts to mitigate the impact of human-induced habitat change.
136

Strategy for the conservation of non-game birds in the state of Nebraska

Canterbury, Jacqueline L. January 1900 (has links)
Thesis (M.A.)--University of Nebraska-Lincoln, 2000. / Title from title screen (site viewed on Feb. 4, 2008). Digitized (PDF) and posted [2007]. Includes bibliographical references (p. 130-138). Also available in paper format.
137

Natural history and conservation biology of a southern West Virginia contour surface mine reptile and amphibian community

Loughman, Zachary James. January 2005 (has links)
Theses (M.S.)--Marshall University, 2005. / Title from document title page. Includes abstract. Document formatted into pages: contains viii, 94 p. Bibliography: p. 92-94.
138

Integrating Multiple Technologies to Understand the Foraging Behavior and Habitat Use of Monk Seals in the Main Hawaiian Islands

Wilson, Kenady Colleen January 2015 (has links)
<p>Hawaiian monk seal abundance is currently declining by about 4% per year with current population estimates around 1,100 individuals. Although the overall population continues to decline, a small sub-population in the main Hawaiian Islands (MHI) appears to be increasing by roughly 6% per year. Monk seal conservation and recovery efforts in the MHI have been hindered by the perception that seals do not belong there, and that they compete with fisheries and damage coral reefs. Education and outreach efforts describing the actual impact of monk seals in the MHI are currently underway, but we actually know very little about their at-sea behavior, especially in the MHI, even though Hawaiian monk seals have been studied extensively since the 1980s. The central objective of my dissertation was to describe monk seal behavior and develop a baseline for monk seal foraging ecology and habitat use in the MHI. To accomplish this I combined three-axis accelerometers, National Geographic Crittercams, and GPS tags to study monk seal foraging behavior. I instrumented 16 seals between 2010 and 2014 on the islands of Molokai, Kauai, and Oahu and deployed an additional 24 GPS tags without the accelerometer and Crittercam. I recovered each Crittercam/accelerometer package 3-6 days after deployment, resulting in an average of 6.14 hours of video footage per seal. The GPS tags continued to record data for 3-6 months providing long-term summaries of dive and haul-out behavior. Using a Bayesian framework I modeled monk seal behavior and habitat use, and developed a method to identify feeding events from accelerometer data. There was a high level of individual variation in the movements of monk seals, but general descriptions of their behavior were accurate at the population level. On average, foraging trips lasted 0.81 ± 1.38 days and seals traveled 28.45 ± 82.03 km per trip. Most seals began benthic dives shortly after entering the water, with most dives occurring between 20-40 m. I used kernel density estimation to define the 50% (core area) and 95% (home range) utilization distribution for each seal. The median home range and core area size for seals in the MHI was 265.62 km2 and 1,564.56 km2, respectively. The pitch axis of the accelerometer was a reliable metric, with over 70% accuracy, for identifying foraging events for monk seals. Body motion over the course of a dive, and how close the seal was to the seafloor during a dive (dive ratio) were the best predictors of these foraging events. Consequently, dive ratio was used to infer foraging in long-term telemetry records that lacked concurrent accelerometer data. Analysis of these data relative to habitat preferences revealed two distinct movement modes for monk seals in the MHI: near shore and offshore/inter-island. My research developed the first thorough understanding of monk seal movements and habitat use in the MHI and provided insight into the mechanisms contributing to the behavioral variability observed for this species. I hope that a detailed understanding of the foraging behavior of monk seals will provide insight into their true role in the ecosystem and help foster the recovery of this critically endangered species.</p> / Dissertation
139

Understanding 'partnerships for conservation gain' : how do government agencies, non-governmental organisations, private landowners and the corporate sector co-operate to deliver effective natural resource management?

Steadman, Janna Elizabeth January 2016 (has links)
With biodiversity loss and ecosystem degradation ongoing, the conservationists' toolkit needs to be augmented by innovative and sometimes bold solutions. It is already apparent that the scale of the problem exceeds the capabilities of any one organisation working in isolation. However, collaboration between stakeholder groups may have the potential to enhance conservation outcomes. Cross-sector collaborations, such as those between non-governmental organisations (NGOs) and corporations, are proliferating in conservation. However, little is known about their efficacy and subsequent impact on the wider natural environment, with many assumptions based on anecdotal rather than empirical evidence. This thesis aims to fulfil an important and substantial knowledge gap by using data-driven approaches to understand partnerships in conservation from the perspective of conservation NGOs. Firstly, I assess the types and prevalence of partnerships between conservation NGOs and corporations and find a diverse range of projects are occurring. For example, financial donations are a frequent form of NGO-corporate interaction, but other collaborative activities such as terrestrial ecosystem restoration and educational activities, are regularly reported. Secondly, I evaluate an NGO-led collaborative network to understand what motivates organisations to initiate a membership committing them to voluntary environmental measures that go beyond regulatory compliance. Results suggest that the majority of members join to fulfil strategic objectives such as reputation protection, rather than for altruistic reasons. Furthermore, participants with stronger sustainability credentials occupy the most influential positions within the network, meaning that they are strongly positioned to receive and disseminate information. Lastly, I use social network analysis to explore how a conservation NGO delivers its landscape-scale conservation projects by acquiring key resources from multiple partners. Results indicate that partners providing land-based support are well connected with one another, meaning that landscape-scale conservation activities can be coordinated more easily. Furthermore, the in-kind support network, primarily comprising NGOs, displays the greatest innovative capacity. The research presented in this thesis highlights that cross-sector partnerships have a central role to play in bridging the interests of different stakeholder groups, and reflect the inclusive vision of conservation we should all be striving to create.
140

Aspects of the conservation biology of the noctule bat (Nyctalus noctula)

Mackie, Iain James January 2002 (has links)
The present study primarily examined habitat selection in the noctule bat by comparing used resources with samples of available resources. The distribution of individual bats of different reproductive status was also investigated, in relation to resources, to enable the prediction of future events under different habitat management scenarios. Individual bats were radio tracked to determine foraging and roosting habitat preferences in a cultural landscape. Noctules consistently preferred to forage over broadleaved woodland and pasture rather than arable land and moorland. A comparison of habitat use and foraging activity demonstrated that non-lactating bats used less preferred habitats significantly more than lactating bats. However, there was little difference in the timing of foraging activity or in the distances traveled to foraging grounds between the two groups. Roosting requirements were identified using data from three separate study sites and intraspecific roosting behaviour was investigated at the radio-tracking site. Noctules consistently selected old woodpecker holes that were larger, further from the ground and in more open situations. Lactating bats changed roosts less frequently and generally occupied one specific roost, which was larger than the other roosts used by the same colony. The echolocation calls used by noctules are particularly suited to monitoring using bat detectors. Formal evidence that noctule calls could be accurately identified from field recordings was obtained by comparing the calls from tracked bats with calls recorded from Leisler's bats.

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