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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.
11

Foraging ecology of wading birds in a sub-tropical intertidal zone

Unknown Date (has links)
The first of five chapters describe the study area and study species, including a short description about the impetus for this research. The second chapter describes a unique hydrologic model for application in tidal ecosystems. The second chapter represents new information on the effects of various abiotic and biotic factors on foraging wading birds in this highly dynamic environment. The third chapter identifies important factors affecting the abundance of foraging wading birds in intertidal environments. The fourth chapter presents a study of the foraging habitat preferences of two wading bird species in intertidal environments. The fifth chapter describes a conceptual model of wading bird foraging ecology and a predictive model of foraging habitat in intertidal zones. The conceptual model captures the major drivers and linkages between the abiotic and biotic variables thought to affect wading bird foraging abundance in intertidal habitats. The conceptual model also identifies major knowledge gaps in our understanding of foraging ecology of wading birds in coastal intertidal areas. The predictive model of foraging habitat is meant to be used by resource managers, but its framework may be useful for ecological studies in general. The final and sixth chapter provides a summary of all the major findings. Each chapter has been written so as to be independent of the other chapters. As such, a full background, along with a discussion of the relevance of the chapter's findings is provided for each chapter. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
12

Diet of the Purple Swamphen in south Florida and invasion pathways of nonnative avian species in Florida

Unknown Date (has links)
The spread of nonnative invasive species has become the second greatest threat to global biodiversity, making management of invasive species a critical component of the conservation of biodiversity worldwide. Managers and conservation biologists often lack basic life history data, as well as quantitative and theoretical models to predict risk of invasion or other negative effects. I contribute information to both categories by providing life history information (diet and morphology) of the Purple Swamphen (Porphyrio porphyrio) and by characterizing the invasion pathways that nonnative avian species in Florida follow. I found Purple Swamphens are predominantly eating and selecting for Eleocharis cellulosa. Additionally, there is a large amount of variation in nonnative avian species’ propensity to colonize natural habitat and the time it takes to do so. Nine out of 15 species investigated colonized natural habitat and the time it took them to do so ranged from 8 to 41 years. It is through a combination of various techniques that ecologists will begin to fully understand the importance of studying nonnative species as well as reducing the impact that nonnatives have on native ecosystems. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015 / FAU Electronic Theses and Dissertations Collection
13

Mechanisms that generate resource pulses and drive wading bird nesting in a fluctuating wetland

Unknown Date (has links)
Variation in the seasonal water level fluctuations of tropical and subtropical wetlands controls the production and concentration of aquatic fauna that support breeding wading birds. However, little is known about how particular components of the annual hydrologic cycle affect processes that control food availability and reproduction. This thesis identifies specific mechanisms responsible for transforming wet season prey standing stock into dry season prey concentrations, links landscape hydrological patterns to wading bird nesting, and presents a predictive model of Wood Stork nesting. I examined the supoort for several a priori hypotheses of factors affecting wading bird prey concentrations and wading bird nest effort. Factors affecting the concentration and vulnerability of prey were important for transferring secondary production to higher trophic levels. Receding water levels, microtopographic variation, and high standing stocks of prey were critical for generating pulses of food availabiltiy to meet the high energy requirements of breeding predatory birds. / by Bryan A. Botson. / Thesis (M.S.)--Florida Atlantic University, 2012 / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
14

Selection of canals and ditches as foraging habitat by wood s7374torks (Mycteria americana)

Unknown Date (has links)
A challenge to ensure the health of wading bird populations is to have a better understanding of the altered habitats that we must now consider part of their natural history. Throughout their range endangered Wood Storks (Mycteria americana) have been reported to forage in ditches, a disparate category of linear man-made waterways. In a 52-kmP 2 P study area on the east coast of central Florida, the characteristics of hydrologically diverse ditches were quantified, and their use by Wood Storks documented during their non-breeding season. Logistic regression analyses were carried out using the ditch characteristics as independent variables and Wood Stork presence/absence as the dependent variable. This study confirms the use of these marginal wetlands, and identifies the significance of emergent vegetation on the foraging habitat selection of Wood Storks in the dry season. / by Eleanor K. Van Os. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.
15

Breeding habitat of Blue Crane (Anthropoides Paradiseus) in Mpumalanga Province, South Africa

Mmonoa, Ernest Mmaphuti January 2009 (has links)
Thesis (M.Sc. (Zoology)) --University of Limpopo, 2009 / The aim of this study was to determine the breeding habitat of Blue Crane (Anthropoides paradiseus) by investigating the home range, habitat selection and habitat suitability. Geographic Information System (GIS) was used as the main tool for analysis. Home range sizes of Blue Cranes were studied during the breeding season using direct observation method. A 50% and 95% Adaptive Kernel was used to estimate home range sizes. The home range sizes were 9.0 ha and 43.5 ha for 50% and 95% Adaptive Kernel, respectively. All the nests were located within 50% Adaptive Kernel, often referred to as core area. The nests were located in agricultural land (mainly pasture) and close to water sources. Habitat selection was studied at nest sites (n = 74) and random sites (n = 200) following site attribute design. The Blue Crane showed a preference to breed in agricultural lands, close proximity to water sources, higher elevation areas, within north eastern sandy highveld vegetation, and north facing slope. The Blue Crane also avoided anthropogenic factors such as built-up land, roads and railway line. ModelBuilder extension of ArcGIS software was used to construct a breeding habitat suitability model for Blue Cranes. Nine habitat variables (water source, slope, aspect, elevation, land use, vegetation, built-up land, roads and railway line) were used in the model. The model was constructed using reclassify and weighted overlay command. Highly suitable sites accounted for 601, 448 ha, while moderately suitable sites accounted for 823, 593 ha, and least suitable sites accounted for 3, 000, 153 ha. This study demonstrated the effective use of GIS technology in analysing the breeding ecology of Blue Crane. The GIS technology provided capabilities for capturing and analysing varied and large data. It was also evident that availability of accurate and complete species data remains vital to enable the full utilization of the GIS technology.
16

Bird community structure and convergence in Afromontane forest patches of the Karkloof/Balgowan range, KwaZulu-Natal.

Wethered, Robyn. 13 December 2013 (has links)
Forest fragmentation is caused by the clearing of patches of indigenous vegetation for agriculture, urban development, and other human land uses. Such action results in patches of remnant natural vegetation being surrounded by altered vegetation. I investigate the effects of forest fragmentation and matrix type on avian diversity and assemblage structure in forest patches of the historically fragmented Karkloof / Balgowan forest range, KwaZulu-Natal, South Africa. This study compares the bird assemblage diversity and composition of indigenous forest patches surrounded by commercial forestry (Gilboa complex) with that surrounded by natural grassland matrix (Balgowan complex). Insularisation of Afromontane Mistbelt forest in KwaZulu-Natal has led to loss of species where forest fragments support fewer bird species than comparably sized patches of mainland forest. Small fragments within natural grassland have fewer bird species per unit area than larger fragments. Forest patch area-dependent density compensation is evident and bird assemblages appear saturated. Bird assemblages are characterised by a non-random species distribution pattern where area-dependent processes are dominant, and the loss of species from fragments follows a deterministic sequence. In forests in the plantation-dominated matrix no island-effect is detectable and it appears that forest patches are converging on the same bird species richness, regardless of forest size. No density compensation is evident and bird assemblages are not saturated. The sequence of species loss from forest patches is not as predictable, where a random yet prominent colonisation process exists. As commercial plantations provide suitable habitat cover for movement of forest birds, colonisation of both distant and small indigenous forest patches has been possible, reducing the effects of area-dependent extinction in the forest patches but also resulting in lower species richness in larger patches. Bird species of the Karkloof / Balgowan forest range appear to be fragmentation adapted, and most species are resilient to further landscape change. Certain species are however more prone to local extinction than others. The major predictors of extinction risk are body size, abundance status, and feeding guild. Patch area is the dominant force governing traits in the natural Balgowan complex where larger species with low natural abundance and an insectivorous diet are most prone to local extinction. In the Gilboa complex the nature of the plantation matrix appears to be masking the species natural responses to fragmentation making it difficult to predict which species are most at risk. In order to preserve maximum bird diversity, including high-risk species, the largest intact forest units (≥302ha) must be conserved. Evidently, the nature of the matrix affects avifaunal diversity and distribution in forest patches, and plantations have the capacity to significantly alter bird assemblage structure and composition in indigenous forest patches. Forest fragments must be considered as integrated parts of a complex landscape mosaic, and this study emphasises the importance of understanding landscape-scale processes. Knowledge of ecological and life history traits proves valuable for predicting community level response to landscape change. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
17

The effects of forest fragmentation on bird species in Madagascar : a case study from Ambohitantely Forest Reserve on the central high plateau.

Langrand, Olivier. January 1995 (has links)
Considering the high rate of endemism in Madagascan organisms, which are mostly restricted to forest ecosystems, and the accelerating rate of deforestation affecting the island, it is critical to understand the effects of forest fragmentation on Malagasy biota to allow for better management of species within ecosystems. Ecological and human-induced changes have led to the disappearance of forest from vast areas of the island, including on the central High Plateau. The Ambohitantely Special Reserve, located on the central High Plateau at 1500 m asl, was selected as the study site for research on the effects of forest fragmentation on forestependent bird species in Madagascar. The Ambohitantely special Reserve covers 5600 ha of which 50% are natural forest, 35% are anthropogenic grassland savannah and 15% are exotic plantations. The forest, described as East Malagasy moist montane forest, is 2737 ha in area, of which 1487 ha are comprised of 513 forest fragments scattered around the largest block totalling 1250 ha. To investigate the effects of forest fragmentation on forest-dependent bird species, seven forest fragments were selected, ranging from 0.64 ha to 136 ha, in addition to the largest block, referred to as the control site. The bird species composition and relative abundance in different-sized fragments were assessed in reference to the control site, by using a combination of two standardized sampling methods: mistnetting and point-counts. A total of 1804 mistnet-days were accrued, 1026 in the control site and 778 in the seven forest fragments, leading to the capture of 491 birds of 26 species. A total of 160 point-counts was made at 39 different sample plots totalling 53 h 29 min of censusing, and a record of 30 species. A total of 72 bird species including 54 breeding forest affinities of the avifauna of Ambohitantely were defined with reference to 32 forest sites scattered across Madagascar. The species composition in all fragments are fully nested subsets of the control site and the species distribution in the fragments does not represent random subsets of the control site. The analysis of the bird communities in different size fragments indicates that the occurrence of bird species reflects a regular pattern of species extinction in relation to decreasing size of forest fragment. Species composition is discussed in reference to Ambohitantely's long history of isolation that may have led to extirpation of bird species from this site. The higher bird taxa decrease in number or totally disappear as a result of their ecological specialization. Equally, they are the most affected by edge effects (e. g. Atelornis pittoides). The main ecological trends in disappearance or extinction of species is a decrease in the number of small-bodied insectivorous understorey species and mid- and upper-stratum small-bodied insectivorous and nectarivorous species. Insectivorous species are particularly affected by forest fragmentation and three forest-dependent species found in Ambohitantely Forest are particularly sensitive to forest fragmentation: Newtonia amphichroa, Calicalicus madagascariensis, and Cyanolanius madagascarinus. The biological (flora species composition and forest structure) and the physical (temperature, moisture, and light) changes generated by the fragmentation of the forest have a greater impact on highly specialized foraging guilds and this explains the pattern of current bird species composition in Ambohitantely Forest. The influence of forest fragmentation on the altitudinal migration process is debated and conservation measures such as the establishment of forest corridors are proposed to improve the protection of biota found in the Ambohitantely Special Reserve. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.
18

A comparision study of migratory raptor distribution and habitat use at the Cape May peninsula stopover

Frank, Cristina A. January 2007 (has links)
Thesis (M.S.)--Rutgers University, 2007. / "Graduate Program in Ecology and Evolution." Includes bibliographical references (p. 62-64).
19

Distribuição de aves limícolas migratórias (Charadriidae e Scolopacidae) em estuários: preferência de habitats e estrutura das assembléias. / Distribution of migratory shorebirds (Charadriidae and Scolopacidae) in estuaries: habitat preference and the assemblage structure.

Cardoso, Tiago Augusto Lima 26 October 2011 (has links)
Made available in DSpace on 2015-09-25T12:18:25Z (GMT). No. of bitstreams: 1 Tiago Augusto Lima Cardoso.pdf: 985032 bytes, checksum: f09cf89072d07aab7edcf296e7fc6a84 (MD5) Previous issue date: 2011-10-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Several studies report the use of estuarine environments by migrant shorebirds in South America. However, distribution patterns of these species among estuarine habitats have been little studied. Our study aimed to investigate the distribution of migratory shorebirds (Charadriidae and Scolopacidae) and the composition and structure of assemblages of several habitats in the estuaries of rivers Mamanguape, Paraíba do Norte and Goiana in the coast of Paraíba, Brazil. Nine sites were selected for counting birds, four in open beach habitats (in ocean front) and five in inner estuarine habitats (tidal flats, a fluvial island and artificial ponds in a shrimp farm). Visual surveys were carried out at each site with the aid of binoculars and a spotting scope. Statistical analyses were applied to answer the following questions: (i) did occur differences in species densities among habitats? (ii) which factor had greatest influence on variations in densities? (iii) how counting sites can be grouped based on structure and species composition of their assemblages of birds? 72 counts were carried out from September 2010 through April 2011, during which 13 species of migratory shorebirds were recorded: Pluvialis squatarola, Charadrius semipalmatus, Limnodromus griseus, Numenius phaeopus, Actitis macularius, Tringa melanoleuca, Tringa semipalmata, Tringa flavipes, Arenaria interpres, Calidris alba, Calidris pusilla, Calidris minutilla and Calidris fuscicollis. Density of species varied significantly among estuaries and categories of habitats, but not among months. The category of habitat was the factor that had greatest influence upon variations of densities. The assemblages of birds in open beaches were clearly different from the assemblages of inner habitats, with regard to their species composition and dominance pattern. The species with greatest importance on differentiation between assemblages of beaches and inner habitats were C. alba, N. phaeopus, C. pusilla and C. semipalmatus. Although we suppose that some factors not measured in this study may have exerted influence upon pattern observed, our results suggest that preferences between open beaches and inner habitats may be influencing distribution of species in estuarine landscape. / Vários estudos relatam o uso de ambientes estuarinos por aves limícolas migrantes na América do Sul. No entanto, os padrões de distribuição destas espécies entre os hábitats estuarinos têm sido pouco estudados. O presente estudo teve como objetivo investigar a distribuição de aves limícolas migratórias (Charadriidae e Scolopacidae) e as diferenças na composição e estrutura das assembléias de diversos hábitats nos estuários dos rios Mamanguape, Paraíba do Norte e Goiana, no litoral do estado da Paraíba, Brasil. Para tanto, foram selecionados nove locais para contagem das aves, sendo quatro em hábitats de praia aberta (de frente para o oceano) e cinco em hábitats interiores aos estuários (lamaçais intertidais, uma ilha fluvial e lagoas artificiais de carcinocultura). Em cada local foram realizados censos visuais com o auxílio de um binóculo e uma luneta. Análises estatísticas foram aplicadas para responder as seguintes questões: (i) ocorrem diferenças nas densidades das espécies entre os hábitats? (ii) qual fator exerce maior influência sobre as variações nas densidades? (iii) de que forma os locais de contagem podem ser agrupados com base na estrutura e composição de espécies de suas assembléias de aves? Ao todo, foram realizadas 72 contagens entre os meses de setembro de 2010 e abril de 2011, durante as quais foram registradas 13 espécies de aves limícolas migratórias: Pluvialis squatarola, Charadrius semipalmatus, Limnodromus griseus, Numenius phaeopus, Actitis macularius, Tringa melanoleuca, Tringa semipalmata, Tringa flavipes, Arenaria interpres, Calidris alba, Calidris pusilla, Calidris minutilla e Calidris fuscicollis. A densidade das espécies variou significativamente entre os estuários e as categorias de hábitats, mas não entre os meses de contagem. O fator que exerceu maior influência sobre as variações na densidade foi a categoria de hábitat. As assembléias de aves que frequentaram as praias abertas foram nitidamente diferentes das assembléias dos hábitats interiores, no que diz respeito à sua composição de espécies e o padrão de dominância. As espécies com maior importância na diferenciação entre as assembléias de praia e interior foram C. alba, N. phaeopus, C. pusilla e C. semipalmatus. Apesar de reconhecermos que fatores não mensurados neste estudo podem ter exercido influência sobre o padrão observado, nossos resultados sugerem que a preferência entre hábitats de praia aberta e hábitats interiores aos estuários pode estar influenciando a distribuição das espécies na paisagem.
20

AVIAN HABITAT SELECTION IN A MIXED CREOSOTEBUSH-GRASSLAND COMMUNITY.

Smith, Brenda Hale. January 1984 (has links)
No description available.

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