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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.
451

Food web architecture in natural and impounded rivers of the Upper Paraná drainage basin, Brazil

Hoeinghaus, David Joseph, January 1900 (has links)
Thesis (Ph. D.)--Texas A&M University, 2006. / "Major Subject: Wildlife and Fisheries Sciences" Title from author supplied metadata (automated record created on Apr. 27, 2007.) Vita. Abstract. Includes bibliographical references.
452

Optimal inter-temporal management of a renewable resource : a policy analysis /

Ward, Kelly John. January 2006 (has links)
Thesis (Ph.D.)--Pennsylvania State University, 2006. / Vita. Includes bibliographical references (p.157-162) and index. Also available online.
453

Avian Use of Floodplain Forest Communities along the Upper Mississippi River

Laaker, Dillan J. 12 June 2018 (has links)
<p> Floodplain forests along the Upper Mississippi River are known to provide valuable habitat for many species of migrating songbirds, including the Cerulean Warbler (<i>Setophaga cerulea</i>) and other species of concern. The forested islands of the confluence region where the Illinois and Missouri Rivers join the Mississippi vary greatly in their structure and composition, providing a variety of habitats for migrating bird species. While past studies have looked at the richness and diversity of bird species across gradients of forest structure, very few have determined which species are characteristic of certain forest types. Effective management and conservation of these lands by state and federal agencies requires that managers understand patterns of species use in these different forest communities. The objectives of this study were (1) to discover how bird community composition varies throughout the floodplain, (2) to determine which vegetation factors, structural or floristic, influence the composition of bird communities, and (3) to identify any species indicative of certain habitat types. Using a protocol developed through a partnership with the U.S. Army Corps of Engineers&mdash;St. Louis District, the Audubon Center at Riverlands, and the Cornell Lab of Ornithology, 10 minute avian point count surveys were conducted from May 15 &ndash; June 30 at 95 survey points located throughout the forested areas of the Upper Mississippi River floodplain. Data collected during the 2017 surveys were added to point count data from the 2015 and 2016 survey seasons. An invaluable tool developed by the U.S. Army Corps of Engineers&rsquo; forestry division, the Forest Management Geodatabase (FMG) was used to analyze structural complexity and vegetation characteristics at each avian point count site, including canopy height, basal area, tree species richness, and understory height. Differences in bird species richness across values of canopy height, basal area, understory height, and tree species richness were explored and tested using single-factor ANOVA. Non-metric multidimensional scaling (NMDS) was used to summarize the pattern of avian community composition among sites and analysis of similarities (ANOSIM) tested for differences in avian communities among forest types. Bird species richness did not differ significantly across values of any of the four forest variables tested. NMDS and ANOSIM found that both canopy height and basal area significantly affected bird community composition while tree species richness and understory height had no effect. Indicator species analysis was then used to identify those species that characterized certain categories of canopy height and basal area. Indicator species analysis found 21 species to be indicators across four discreet categories of canopy height and 23 species to be indicators across 4 categories of basal area. Indicator species of note included five focal species: Indigo Bunting, Prothonotary Warbler, American Redstart, Warbling Vireo, and Red-shouldered Hawk. Warbling Vireos were indicators for sites with canopy heights less than 9 meters, while Prothonotary Warblers were characteristic of sites with the largest values of basal area (> 75 m<sup> 2</sup>/ha). These focal species are chosen by the Audubon Center at Riverlands and are deemed important to the region or species of concern, making them targets of conservation. The knowledge of bird species-habitat relationships gained from this study is critical for the successful management of floodplain forest in order to benefit Neotropical migratory bird species on the Upper Mississippi River System.</p><p>
454

Genetic Assessment of Native and Non-native White-Tailed Deer (Odocoileus virginianus) in the Southcentral U.S.

Youngmann, Jordan L. 03 January 2019 (has links)
<p> Population genetics of white-tailed deer (<i>Odocoileus virginianus </i>) have been influenced through human actions including the translocation of deer from across the United States in the 1900s and, recently, the creation of the captive-cervid industry, which uses animal husbandry to manipulate genetic variation. To assess the effects of these actions, I studied the genetic variation of free-range and captive populations of deer across the southcentral U.S. using a 14 microsatellite panel. In free-range populations I found genetic structure that divided deer west to east along the Mississippi River. Additionally, I found that captive populations were genetically distinct from geographically proximate free-range populations. However, after 2 generations of hybridization, this distinction disappeared. Finally, using both Bayesian clustering and multivariate approaches, I was able to identify a non-native individual from local freerange populations in southern Mississippi. Using these methods, wildlife managers can further investigate cases of hybridization between non-native deer and free-range populations.</p><p>
455

Cardiovascular disease in free living wild animals with particular reference to the African elephant (Loxodonta africana)

Sikes, Sylvia K. January 1967 (has links)
A field survey to investigate the ecology of cardio-vascular disease in free living wild animals is described. Its aim was i) to assess the susceptibility of such animals to arteriosclerosis. and particularly to athero-sclerosis ii) to examine in greater detail the ecology of oardiovascular disease in a single, naturally-susceptible species in relation to dietary change and stress in naturally occurring situations. A total of 201 specimens, representing species of mammals and 25 of birds, was examined: 37 species of mammals had uncomplicated lipid deposits in the arterial intima, thought to represent a normal physiological occurrence; 13 had atheroma-like lesions of the intima; 20 species of birds shoved positive lipidosis. These findings. compared with those reported in taxonomioally equivalent groups of captive animals, are discussed. The African elephant was selected for special study. The eoology of its cardiovascular disease patterns was studied in three different habitat types: one natural (the 'control'). and two degenerate ('stressed'). Athero-sclerosis and medial sclerosis were found not to occur in the 'natural' habitat type, but to be directly correlated with habitat degeneration in the other two 'stressed ranges, where 'stress' factors included excessive exposure to sunlight, dietary changes, frustration of the migrator/ habit, disrupted calving patterns9 and over-population neither disease was found to be directly related to age, and each had a distinct intra-arterial development patterns the aetiology of each is therefore thought to be basically independent, although in advanced cases interaction may occur. Incidental results of the survey includes i) observations on the importance of relating the functional anatomy of the arterial supportive thickenings at ostia, bifurcation and regions of mechanical strain to the normal intra-aortic distribution of uncomplicated intimal lipid deposits; ii) observations on a valve-like structure in the aorta of the klipspringer; and iii) the formulation of a new field technique for assessing relative age in the African elephant.
456

Urban Coyote (Canis latrans) Ecology| Diet, Activity, and Habitat Use

Collins, Rita 18 September 2018 (has links)
<p> Non-habituated coyotes (<i>Canis latrans</i>) avoid direct interactions with humans. Reliance on human food sources has been linked to gradual habituation, a precursor to conflict and attacks on domestic pets and humans. Diet and activity patterns of urban coyotes inhabiting natural fragments in Long Beach, CA were monitored through scat collection and camera trapping over a year (Aug 2016 &ndash; Aug 2017). Local urban coyotes are relying predominately on natural foods, with an increase in mammalian prey in the wet season and an increase in vegetation and insect consumption in the dry season. Anthropogenic items, food and food related inedible items, appeared in 14% of scats overall, with no significant seasonal change. Cat remains were found in 14% of scat samples, but only triggered cameras once throughout the 2,857 camera nights of the study. Coyote activity was centered on nights in both seasons, with greater dawn activity in the dry season, indicating an avoidance of peak human activity. This reliance on natural foods and avoidance of human activity reduces the opportunities for human-wildlife conflicts in our local area.</p><p>
457

Linking Diet, Behavior, and Bioenergetics of a Migratory Waterbird to Evaluate Response to Wintering Ground Conditions

Boggie, Matthew Arthur 07 November 2018 (has links)
<p> Rivers in semi-arid regions are highly sensitive and pressured yet can support diverse assemblages of species. In central New Mexico, the Rio Grande (River) is the lifeblood of the Middle Rio Grande Valley (MRGV), a semi-arid region which maintains large urban and agricultural centers and is also the principal wintering area for the Rocky Mountain Population of greater sandhill cranes (<i>Antigone canadensis tabida</i>). Human-induced environmental change has transformed the MRGV and habitat availability prompting concerns for the population. To address these concerns, I investigated dietary and behavioral responses of sandhill cranes to the collection of features that function as winter habitat. In Chapter 1, I demonstrated a novel application of stable isotopes to evaluate dietary reliance of sandhill cranes on corn subsidies provisioned by natural resource agencies, estimated rates of carbon isotope incorporation in tissues of sandhill cranes, and estimated tissue-derived winter arrival dates of sandhill cranes. I found subsidized corn was the primary dietary component of sandhill cranes, rates of carbon isotope incorporation in sandhill crane tissues differed predictably by metabolic activity, and estimated tissue-derived arrival dates on wintering grounds approximated actual arrival dates. In Chapter 2, I advanced a hierarchical Bayesian framework for overcoming challenges and improving analysis of behavioral data frequently generated in animal behavior studies and used behavioral observations of sandhill cranes as a case study. In Chapter 3, I estimated energetic and temporal availability of corn subsidies and seasonal energy requirements of sandhill cranes. I found seasonal energetic requirements of the population are likely satisfied by corn subsides but not without strategic planning. In Chapter 4, I examined how current landscape and riverine configuration influenced patterns of diel habitat selection by sandhill cranes. Sandhill cranes avoided sources of anthropogenic disturbance, relied heavily on managed public land resources, and selected roosting locations in the Rio Grande with a wider channel, interspersion of sandbars and shallow water, and low channel bank vegetation. My research suggests sandhill cranes have coped with alterations that have led to current conditions in the MRGV, however, habitat-related resources will need to be managed adaptively as drivers of environmental change will undoubtedly influence future circumstances. </p><p>
458

Response of Waterbird Communities to Habitat and Landscape Structure along an Urban Gradient in Phoenix, Arizona

January 2016 (has links)
abstract: Urban riparian corridors have the capacity to maintain high levels of abundance and biodiversity. Additionally, urban rivers also offer environmental amenities and can be catalysts for social and economic revitalization in human communities. Despite its importance for both humans and wildlife, blue space in cities used by waterbirds has received relatively little focus in urban bird studies. My principal objective was to determine how urbanization and water availability affect waterbird biodiversity in an arid city. I surveyed 36 transects stratified across a gradient of urbanization and water availability along the Salt River, a LTER long-term study system located in Phoenix, Arizona. Water physiognomy (shape and size) was the largest factor in shaping the bird community. Connectivity was an important element for waterbird diversity, but not abundance. Urbanization had guild-specific effects on abundance but was not important for waterbird diversity. Habitat-level environmental characteristics were more important than land use on waterbird abundance, as well as diversity. Diving and fish-eating birds were positively associated with large open bodies of water, whereas dabbling ducks, wading birds, and marsh species favored areas with large amounts of shoreline and emergent vegetation. My study supports that Phoenix blue space offers an important subsidy to migrating waterbird communities; while alternative habitat is not a replacement, it is important to consider as part of the larger conservation picture as traditional wetlands decline. Additionally, arid cities have the potential to support high levels of waterbird biodiversity, heterogeneous land use matrix can be advantageous in supporting regional diversity, and waterbirds are tolerant of urbanization if proper resources are provided via the habitat. The implications of this study are particularly relevant to urban planning in arid cities; Phoenix alone contains over 1,400 bodies of water, offering the opportunity to design and improve urban blue space to optimize potential habitat while providing public amenities. / Dissertation/Thesis / Masters Thesis Applied Biological Sciences 2016
459

An Evaluation of New England Cottontail Habitat Restoration

Warren, Alena 14 March 2018 (has links)
<p> Several state, federal and non-profit agencies have developed collaborative goals for restoring habitat in New England and New York for a declining rabbit species, the New England cottontail (<i>Sylvilagus transitionalis</i>, NEC). My goal was to evaluate habitat restorations at both the local, or site, scale, and the landscape scale. In order to objectively quantify the suitability of the sites being managed, I developed a Habitat Suitability Index, based on the HSI models designed the U.S. Fish and Wildlife Service. I identified candidate habitat variables for NEC, including types of cover and refuges, and food, and then asked a panel of NEC experts to rank the importance of the candidate variables. I collected data on the most important habitat variables at 60 sites managed for NEC across New England and eastern New York. The NEC experts also ranked the same 60 sites from 1 (unsuitable) to 5 (optimal). The model was optimized to improve agreement with expert opinions for the 60 sites. Specific applications may include determining when a site is suitable for releasing translocated or captive breed rabbits, and identifying habitat features that need modification as forest succession progresses. To evaluate habitat restoration efforts at a larger landscape scale, I created metapopulation models for two management focus areas (Cape Elizabeth and Kittery-Berwick) in Maine for population viability analyses. I ran simulations to compare the relative effects of the two focus areas as well as five management scenarios. I conducted a sensitivity analysis to determine the importance of various model parameters on extinction risk. The Cape Elizabeth focus area, which has more habitat patches that are closer together, had lower extinction risks than Kittery-Berwick. Reintroductions and creating additional habitat appeared especially important in the Kittery-Berwick focus area. The simulation results were sensitive to changes in the standard deviations of the survival and recruitment rates, and the probability of catastrophic mortality, indicating that variation is detrimental to NEC metapopulation growth. Variation in weather caused by climate change may need to be mitigated by monitoring and managing NEC habitat and populations.</p><p>
460

Modeling the Effects of Animal Movements and Behavior on Spatial Patterns of Seed Dispersal in Fragmented Landscapes

Jones, Landon Richard 03 May 2018 (has links)
<p> Habitat loss and the resulting fragmentation can alter animal movements and disrupt animal seed dispersal mutualisms; however, these effects on spatial patterns of seed dispersal are not well understood. To explore the effects of habitat loss and fragmentation on seed dispersal distances and seed dispersion (aggregation), I created a spatially-explicit, individual-based model of an animal dispersing seeds (SEADS &ndash; Spatially-Explicit Animal Dispersal of Seeds). For Chapter 1, I ran SEADS in a theoretical landscape of 0-90% habitat loss to determine the effects of habitat loss on three animal traits relevant to seed dispersal: movement distance, gut retention time, and time between movements. SEADS results revealed a complex interaction involving all animal traits and habitat loss on dispersal distances and dispersion, driven by a novel underlying mechanism of fragment entrapment. Unexpectedly, intermediate habitat loss could increase dispersal distances and dispersion relative to low and high habitat loss for some combinations of animal traits. In Chapter 2, I developed a new method (TriAD) to estimate animal locations from triangulation data to improve triangulations for toucans. Location estimates calculated with TriAD averaged 23-63 m closer to true locations for three of four distance classes compared to the traditional method (Lenth&rsquo;s maximum likelihood estimator, LMLE). Additionally, over 99% of 570 triangulations converged for TriAD compared to 85.8% for the LMLE. For toucan data, 98.0% of 4445 triangulations converged in TriAD compared to 88.6% for the LMLE. In Chapter 3, I parameterized SEADS with data from toucan movements and gut retention trials collected in Costa Rica to evaluate the effects of landscape, body size, and social organization on seed dispersal. The larger, less social species dispersed seeds 17-28% farther and in less aggregated patterns than the smaller, social species. This pattern was driven by longer movements in the larger species, suggesting that body size is more important than social organization for seed dispersal in our system. Habitat use and home range sizes limited dispersal distance and dispersion for both species. Findings from our simulations illustrate the importance of separating and quantifying the effects of disperser behaviors and landscape effects that shape seed deposition in fragmented areas.</p><p>

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