• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 47
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 65
  • 65
  • 39
  • 19
  • 10
  • 8
  • 6
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 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.
31

Factors Influencing Annual Survival and Recovery Rates, Primary Feather Molt, and Hatch Chronology of White-winged Doves in Texas

Hall, Jared Daniel 19 May 2018 (has links)
<p> Understanding survival and breeding season length of game birds are important for effective management and conservation. By determining the variables that drive survival and recovery rates for white-winged doves (<i>Zenaida asiatica</i>), I can offer management implications to agencies across their range. There is currently little knowledge about white-winged dove molting and hatching chronology. The objectives of this study were to: 1) investigate annual survival and recovery rates of white-winged doves, 2) determine intrinsic and extrinsic factors influencing them, 3) determine AHY primary feather molt rate and the factors that influence molt rate and initiation, and 4) describe hatch chronology and determine the factors that influence hatching. To understand what influences annual survival and recovery, I examined subpopulation, climate variables, urbanization characteristics, molt, and band type as covariates. I used the Brownie approach in the RMark package of R to compare annual survival and recovery models and generate estimates. I used Underhill and Zucchini models in the Moult package of R to determine AHY primary feather molt rate and the best predictors of molt rate and initiation. I analyzed molt scores of HY doves recorded during annual banding using GLMs in R to determine the factors that influence hatching. I used AIC to select the most parsimonious models for each <i>a priori</i> candidate set. I analyzed 71,675 bands, of which, 3,086 were recovered from 2007 &ndash; 2016. My most supported model influencing survival and recovery was [<i>S</i>(age class x urban intensity) <i>f</i>(age class X MRPP)]. Average AHY primary molt rate across Texas was 13.21 &plusmn; 0.93 days. MRPP subpopulation + Year was the most supported model influencing AHY primary molt rate, AHY molt initiation, and hatch date. Within my sample, 95% of AHY white-winged doves began molting from 7 April to 8 July and completed molt 17 August to 17 November. White-winged doves hatched as early as 6 January and as late as 27 July, with 95% of all hatching occurring between 22 March and 18 June and peaking at 5 May. Urban intensity was an important variable influencing annual survival, which is expected for such an urbanized species. MRPP subpopulations influenced vital rates and should be considered for future harvest management. </p><p>
32

Distributions of large mammal assemblages in Thailand with a focus on dhole (Cuon alpinus) conservation

Jenks, Kate E 01 January 2012 (has links)
Biodiversity monitoring and predictions of species occurrence are essential to develop outcome-oriented conservation management plans for endangered species and assess their success over time. To assess distribution and patterns of habitat use of large mammal assemblages in Thailand, with a focus on the endangered dhole (Cuon alpinus), I first implemented a long-term camera-trapping project carried out with park rangers from October 2003 through October 2007 in Khao Yai National Park. This project was extremely successful and may serve as a regional model for wildlife conservation. I found significantly lower relative abundance indices for carnivore species, and collectively for all mammals compared to data obtained in 1999–2000, suggesting population declines resulting from increased human activity. I integrated this data into maximum entropy modeling (Maxent) to further evaluate whether ranger stations reduced poaching activity and increased wildlife diversity and abundances. I then conducted a focused camera trap survey from January 2008 through February 2010 in Khao Ang Rue Nai Wildlife Sanctuary to gather critical baseline information on dholes, one of the predator species that seemed to have declined over time and that is exposed to continued pressure from humans. Additionally, I led a collaborative effort with other colleagues in the field to collate and integrate camera trap data from 15 protected areas to build a country-wide habitat suitability map for dholes, other predators, and their major prey species. The predicted presence probability for sambar (Rusa unicolor) and leopards (Panthera pardus) were the most important variables in predicting dhole presence countrywide. Based on my experience from these different field ecological surveys and endeavors, it became clear that local people's beliefs may have a strong influence on dhole management and conservation. Thus, I conducted villager interview surveys to identify local attitudes towards dholes, document the status of dholes in wildlife sanctuaries adjacent to Cambodia, and determine the best approach to improve local support for dhole conservation before proceeding with further field studies of the species in Thailand. A photograph of a dhole was correctly identified by only 20% of the respondents. My studies provide evidence that some protected areas in Thailand continue to support a diversity of carnivore speices of conservation concern, including clouded leopards (Neofelis nebulosa), dholes, and small felids. However, dholes' impact on prey populations may be increasing as tiger (Panthera tigris) and leopards are extripated from protected areas. The next step in dhole conservation is to estimate the size and stability of their fragmented populations and also focus on maintaining adequate prey bases that would support both large felids and dholes.
33

Population and spatial ecology of tigers and leopards relative to prey availability and human activity in thung yai naresuan (east) wildlife sanctuary, Thailand

Vinitpornsawan, Supagit 01 January 2013 (has links)
The Thung Yai Naresuan (East) Wildlife sanctuary (TYNE) is clarified as the Tiger Conservation Landscape of Global Priority and also a stronghold for other endangered and threaten species. Although, UNESCO designated this area, the cores of the Western Forest Complex (WEFCOM), as a Natural World Heritage Site in 1991, this wildlife has been threatened by habitat alteration, prey depletion, and direct killing. Yet, the information on impact of human activities and wildlife status that is needed to guild forest authorities to develop conservation strategies remains challenging. The goal of this dissertation was to increase understanding of tiger, other main predators, prey status, and also impact of human activities in the sanctuary. In the TYNE, the globally endangered species were observed including Asiatic Elephant (Elephas maximus), Tiger (Panthera tigris), Malayan Tapir (Tapirus indicus), Dhole (Cuon alpines), and Malayan Pangolin (Manis javanica). Spatially explicit capture-recapture approach estimated tiger density at 1.4-1.6 tigers/100 km2 and leopard density at 0.7-0.8 leopards/100 km2, which indicates that there might be 27±10 tigers (95% CL range from 11-46) and around 12±4 leopards (95% CL range from 8-19) roaming in the area around 1,596 km2 in TYNE. The large predators like tigers, leopards, and dholes co-occurred in the area with the combination of both spatial and temporal partitioning due to differences in predator and prey activity and low overlap in space use correlated to their prey preferences. Prey availability, human settlement areas, and human disturbance activities are the key limiting factors for their distribution and space-use. The habitat use of tiger and leopard demonstrated that the population distribution was limited in the central to the eastern part of the TYNE, while the local people occupied the west with high disturbance activities. The activities by local people in TYNE were varied and the impacts of the disturbance were complex. Slash and burn, livestock, tree cutting, and poaching appeared to be the major influence wildlife abundance and habitat around the settlement areas. The results of this study stress the need for the further conservation and management to maintain wildlife distribution and populations in the future. Better scientific understanding of wildlife biology, ecology, and social sciences would help to deal with the conservation and management issues facing the local communities and natural resources in Thung Yai Naresuan (East) Wildlife Sanctuary.
34

Vulnerability of longfin inshore squid (Loligo pealeii) to predation: The influence of relative prey size and behavior

Staudinger, Michelle Dana 01 January 2010 (has links)
Cephalopods provide forage to a wide range of predators in marine food-webs. Despite their ecological importance, a basic understanding of the mechanisms controlling predation risk and demand is lacking. This is true of one of the most common species of squid found in the northwest Atlantic, the longfin inshore squid (Loligo pealeii). In this dissertation, I address this shortcoming by investigating the role that size and behavior play in influencing squid’s vulnerability to predation. I used long-term food habits, population survey, and commercial landings data, to quantify size-based patterns of predation respective to 25 species of predators. Additionally, I estimated the amount of overlap between predatory consumption and the fishery catch for squid by size. I found that finfish and elasmobranchs generally consumed juvenile and sub-adult squid, while marine mammals primarily targeted adults. Consequently, marine mammals had the highest overlap with the fishing industry for squid size resources. Although large squid were not common in predator diets, predators did not appear to be gape-limited when feeding on squid. This suggested that other factors, including behavior, were important in shaping size-based patterns of predation. I used a laboratory-based approach to quantify attack and capture behaviors towards squid by two predators representing contrasting foraging tactics. Bluefish (Pomatomus saltatrix) and summer flounder ( Paralichthys dentatus) were chosen as cruising and ambush predators, respectively. Patterns in attack rates suggested that size-selection on squid was constrained by passive processes rather than active choice in both predators. Size-dependent profitability functions were calculated by combining capture success rates, handling times, and relative prey mass, and determined that bluefish was the more efficient predator of squid. Lastly, I evaluated the occurrence and effectiveness of anti-predator responses used by squid in the presence of bluefish and flounder. Squid behavior depended on the type of predator present, and the survival value of primary and secondary defense behaviors differed during interactions with each predator. The results of this project are intended to improve the quality of management of squid and their predators by providing a better understanding of predator-prey interactions in the northwest Atlantic.
35

The economics of community-based wildlife conservation in Zimbabwe

Muchapondwa, Edwin. January 1900 (has links)
Thesis (Ph. D.)--Göteborg University, 2003. / Title from home page (viewed June 21, 2004). Added t.p. with thesis statement inserted. Includes bibliographical references. Also available in print.
36

Restoration of endangered epiphytic lichens in fragmented forest landscapes the importance of habitat quality and transplantation techniques /

Lidén, Marlene, January 2009 (has links) (PDF)
Diss. (sammanfattning) Umeå : Sveriges lantbruksuniversitet, 2009. / Härtill 5 uppsatser.
37

Post-treatment erosion of decommissioned forest road stream crossings /

Wilson, Sarah Elisabeth. January 1900 (has links)
Thesis (M.S.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 45-47). Also available via Humboldt Digital Scholar.
38

Risk analysis and use of stochastic population models for determining Endangered Species Act status of North Pacific marine mammals /

Gerber, Leah R. January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [110]-122).
39

Approaches to management effectiveness in state fish and wildlife agencies /

McMullin, Steve L., January 1993 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 309-317). Also available via the Internet.
40

Modeling the role of no-take marine reserves in fisheries management /

Gilbert, Deidre F., January 2002 (has links) (PDF)
Thesis (M.S.) in Marine Policy--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves - ).

Page generated in 0.1414 seconds