Dissertations / Theses on the topic 'Habitat features'
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1
Bonnett, Martin Lee. "Critical habitat features of giant kokopu, Galaxias argenteus (Gmelin 1789)." Thesis, University of Canterbury. Zoology, 2000. http://hdl.handle.net/10092/6892.
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The giant kokopu (Galaxias argenteus) is the largest of the galaxiid fishes, and is endemic to New Zealand. Some landlocked (non-migratory) populations exist, but giant kokopu are normally diadromous, and juveniles make up a small part of the annual whitebait run. The species is now regarded as threatened, and its rarity has led to controversy over proposed changes to whitebait fishing regulations. Although exploitation of the juveniles may be limiting recruitment to adult populations, the perceived decline of giant kokopu has been attributed mostly to the loss and degradation of its habitat. In order to manage and conserve the species, the critical features of giant kokopu habitat need to be determined.
Analysis of information from the New Zealand Freshwater Fisheries database, and from field surveys in Southland and along the western coast of the South Island, indicate that five habitat features are critical: the presence of instream cover, deep water, low water velocity, proximity to the sea, and overhead shade/riparian cover. These features were critical in both regions surveyed and for both juvenile and adult fish. The effects of different types of riparian and in stream cover were examined, but it appeared that the presence of some sort of cover was more important than its composition. Giant kokopu readily utilised artificially constructed habitat, which emphasised the importance of instream cover and low water velocity.
Diet was investigated from the examination of the gut contents of 105 fish, and results compared to other published information. Giant kokopu are probably best described as opportunistic feeders, as they utilise a wide range of foods of both aquatic and terrestrial origin. Terrestrial components of the diet appear to be significant for giant kokopu, which may partly explain the importance of overhead shade and riparian cover in giant kokopu habitat.
Giant kokopu have been found in a wide variety of water types around New Zealand, and are known to co-occur with 33 other native and introduced species of fish. It appears that they are more likely to occur in habitats where introduced brown trout (Salmo trutta) are absent, although the two species do sometimes co-occur and cannot be said to be mutually exclusive.
Migrations of juvenile (whitebait) giant kokopu into freshwater probably occur mostly after the end of the whitebaiting season, and their capture may no longer be a serious conservation concern. The impact of commercial eel fishing on giant kokopu populations is difficult to determine, and there may well be both detrimental and beneficial effects.
The conservation and management of giant kokopu will probably continue to be based upon management of their habitat, and these processes will be enhanced by the knowledge of the species' habitat requirements.
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Marshall, Livingston Sinclair Jr. "Survival of juvenile queen conch, Strombus gigas, in natural habitats: Impact of prey, predator and habitat features." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539616765.
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In this dissertation, I experimentally examine predation-induced mortality upon juvenile queen conch, Strombus gigas, and assess the importance of select habitat predator and conch characteristics affecting predation intensity. Experiments were conducted during the summer and early fall of 1987, 1988, 1990 and 1991 in seagrass beds and adjacent sand flats near Lee Stocking Island, Exuma Cays, Bahamas. These experiments indicate that various factors act interactively to produce habitat-specific mortality rates in queen conch due to predation. These include (1) habitat type, whereby seagrass beds offer some protection; (2) local population dynamics, such that populated seagrass beds appear to enhance conch survival; (3) population density in some seagrass beds, such that mortality is inversely density-dependent; (4) conch size, such that larger conch have higher survival rates, depending on the specific type of habitat; and (5) predation intensity and predator guilds, which likely differ across habitats, producing habitat-specific mortality rates. When integrated with complementary studies of queen conch trophodynamics, these results provide critical information regarding key ecological factors affecting conch survival. In particular, results from the hatchery-reared experiments demonstrate the potential use of hatchery-reared stocks in natural habitats, and hence a valuable option for enhancement of fishery stocks throughout the Caribbean. In general, the integration of results obtained in this dissertation, with complementary studies of queen conch trophodynamics, should provide valuable suggestions of queen conch habitats, densities and scales of patchiness producing highest survivorship and growth rates in nature.
3
Gude, Andrew Greiff. "An Assessment of the Riparian-influenced Salmonid Habitat Features of Johnson Creek, Portland, Oregon." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/5232.
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Pacific salmon populations in Johnson Creek, Portland, Oregon have been adversely impacted by urbanization, and by residential and agricultural land development. f Ecological impacts include loss or depletion of riparian vegetation features which directly influence stream and associated salmonid ecology. This research examines the nearstream riparian zone's contribution to instream habitat complexity for anadromous salmonids in Johnson Creek. Visual surveys were conducted on over half the stream length. Five features were assessed to determine the extent of riparian influenced stream habitat including, overhead enclosure, overhanging vegetation, undercut banks, and large and small woody debris and root wads. The stream survey showed that areas of riparian-influenced habitat are spatially intermittent and present in areas of the least stream disturbance. Suitable riparian habitat is limited to locations where there is minimal riparian disturbance, property management, and channelization. I Although salmonid populations have been reduced, insufficient riparian influenced salmonid habitat features are not the primary limiting factor on salmon populations. Other factors such as pollution, sedimentation, hatchery fish introduction, low flows, inadequate food supplies, high stream temperatures, repress wild salmon populations.
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Stolarski, Jason Thomas. "Age and growth of Appalachian brook trout in relation to life-history and habitat features." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5482.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains v, 93 p. : ill., map. Vita. Includes abstract. Includes bibliographical references.
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Davies, Jaime Selina. "Mapping deep-sea features in UK waters for use in marine protected area network design." Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1200.
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With an increase in demand on deep-sea resources comes a need for appropriate and effective management of this ecosystem. The establishment of a representative network of deep-sea Marine Protected Areas offers one tool with which to address the conservation needs of the deep sea. While a number of deep-sea habitats have been identified as vulnerable to anthropogenic activities (e.g. cold-water coral reefs and sponge aggregations), poor knowledge of the distribution of these habitats hinders conservation efforts and network planning, and thus we need habitat maps. With improvements in acoustic data resolution acquired from the deep sea, and the ability to cover large areas rapidly, the use of acoustic techniques in mapping biological habitats is growing. Multibeam bathymetry and its derived terrain variables can potentially provide important information that can aid in the delineation and characterisation of biological communities. A necessary prelude to mapping is therefore the definition of biological assemblages for use as mapping units. Two megahabitat features (seamount and submarine canyons) were sampled using acoustic and ground-truthing to characterise and map the distribution of benthic assemblages. Species were identified as distinct morpho-types and catalogued, and still images quantitatively analysed. Standard multivariate community analysis was undertaken to define distinct faunal assemblage that may act as mapping units. Those clusters identified by the SIMPROF routine were taken against a set of criteria to reject/accept as robust assemblages that may be used as mapping units. Twenty two benthic assemblages or biotopes were defined from multivariate analysis of quantitative species data, 11 from the SW Approaches and 11 from Anton Dohrn Seamount, and a further one from video observations (SW Approaches). Taken against current definitions, 11 of these were considered as Vulnerable Marine Ecosystems (VME). Diversity was measured to compliment the comprehensive description of biotopes. The use of multivariate diversity indices proved better for comparing diversity of biotopes as it captures a more than one aspect of diversity of the community. Two biotopes were common to both megahabitat features, cold-water coral reef habitats, and those from Anton Dohrn Seamount were more diverse than from the SW Approaches. Modelling techniques were employed to test the relationship between biotopes and environmental and geophysical parameters, which may be used as surrogates to map VME. Generalised Additive Models of Vulnerable Marine Ecosystems revealed multibeam bathymetry and its derived parameters to be significant surrogate for mapping the distribution of some assemblages, particularly those that appear to be influenced by current regime; whilst not so well for those whose distribution is not so strongly current driven e.g. soft sediment communities. In terms of deep-sea mapping, the use of multibeam can prove a useful mapping tool if the resolution of the data is at an appropriate scale that will identify meso-scale geomorphological features, such as cliff-top mounds, that may act as proxies for occurrence of biotopes, but this relationship is still unclear. Surrogates were used to map VME across the seamount and submarine canyons, and full coverage maps were produced for all biotopes occurring on these megahabitat features.
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Dempsey, Alexandra C. "Global Evaluation of Platform-Top Sedimentary Features." NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/170.
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Remote sensing has transformed coral reef science in the last decades. It is now possible to audit reef health and geomorphology at global scale and very high spatial resolution. This work utilizes the vast and no-cost archive of imagery housed within Google Earth (GE). GE was used to interrogate the morphometric properties (size, shape, complexity, etc) of the components that combine to yield a reef environment (reef structures, sediment sheets, and so forth). The data populated a morphometric database for reefs globally that are partitioned by their architecture. The database has been investigated using information theory. The aim of the work is to identify whether motifs of carbonate platforms within these reef types are predictable on the basis of environmental parameters. The results are relevant to assess depositional patterns to develop rules for predicting how facies are distributed in modern systems and ancient reservoirs.
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Lange, Marc. "Abundance And Diversity Of Fish In Relation To Littoral And Shoreline Features." Thesis, University of Guelph, 1999. http://hdl.handle.net/10919/71522.
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The effects of small-scale shoreline residential development on littoral fish abundance and species richness was examined at three different scales of observation (within 122, 244, and 488 meters) in Lake Simcoe (Ontario, Canada). A mixed model regression was used to test for effects of development after accounting for seasonal and spatial variation in environmental variables known to affect distribution and abundance of fish. Fish were aggregated near single development structures, such as permanent docks, and repelled from other single structures, such as bank stabilisation. Shoreline developed with multiple features, such as docks combined with break walls, tended to be positively correlated with fish abundance but negatively correlated with species richness. Features such as docks and break walls combined with boathouses were generally associated with a decrease in both abundance and richness. Cluster analysis detected no consistent pattern of association between specific fish assemblages and residential development across the three scales of observation. Increased density and diversity of shoreline residential development tended to be associated with reduced fish abundance and species richness. The specific development features associated with these patterns change with the scale of observation, indicating that fish responded to proximally and distantly located habitat alterations.
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McCaffrey, Rachel. "Assessing Patterns of Abundance and the Influence of Habitat Features and Scale on Birds in an Urban Environment." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194004.
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My doctoral research focused on birds in the urban environment of Tucson, Arizona. Urban environments present unique challenges and opportunities for ecological research and conservation, and my work illustrates these aspects. From 2003-2008, I coordinated the Tucson Bird Count (TBC), a citywide bird survey program conducted by volunteer birders. My work with the TBC suggests that citizen-scientists may represent a valuable resource for ecologists because they can collect data over large scales and/or time periods. However, the environmental changes induced by humans in urban areas can also have significant negative impacts on native wildlife. My research indicates that for many native bird species, these impacts can be reduced through the actions of individual homeowners, neighborhood groups, and city and regional planners and managers. In working to maintain these species, it is important to consider both the specific habitat features important for each species, as well as the scale at which the species respond to these features.
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Layman, Bruce Clare. "Role of Habitat Features and Chemical Cues in Substrate Selection by Blue Crab Megalopae: Evidence from Laboratory Experiments." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539617647.
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Morgado, Mariana Rodrigues. "Influence of social and land use features on urban avifauna." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16426.
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Mestrado em Ecologia AplicadaUrbanization is a worldwide phenomenon that affects biodiversity, which induces the need to conserve the urban areas. Urban ecosystems are defined by human activities, habitat infrastructures and vegetation components. Nevertheless, little is known about the processes underlying the spatial variation of urban bird communities. The aims of the present dissertation are (1) to investigate the relationship between avian diversity and abundance with land use and social features and (2) to study the vertical distribution of avian diversity, abundance and biomass in an urban environment. For this purpose, bird surveys by point counts were conducted during breeding season in eight neighbourhoods of Aveiro, Portugal. The data was analysed through descriptive analyses, statistical hypothesis testing and generalized linear models. Most of the studied neighbourhoods were dominated by omnivorous species, namely Columba livia and Passer domesticus. The results also show that species richness is higher in neighbourhoods furthest away from esplanades, with higher density of trees, building height and density, alongside low imperviousness, busy streets and human population density. Moreover, neighbourhoods furthest away from esplanades, showing higher building age, height and density, busy streets but lower human population density, hold higher avian abundance. Medium height levels exhibit higher bird diversity, abundance and biomass than both lower and higher height levels. These findings strongly suggest that focusing on a combination of local land use and social features, rather than single features, provide a better understanding of avian diversity and spatial structures of urban bird communities. Furthermore, due to the complexity of urban ecosystems, this investigation underlies the relevance of integrating social and urban planning researchers into urban ecological studies.
A urbanização é um fenómeno mundial que afeta a biodiversidade, o que induz a necessidade de conservar as áreas urbanas. Os ecossistemas urbanos são definidos pelas atividades humanas, infraestruturas do habitat e componentes vegetais. No entanto, pouco se sabe sobre os processos inerentes à variação espacial local de comunidades de aves urbanas. Os objetivos principais da presente dissertação consistem em (1) investigar a relação entre diversidade e abundância de aves, e fatores sociais e de uso do solo e (2) estudar a distribuição vertical da diversidade, abundância e biomassa de aves em ambiente urbano. Para este efeito foram realizados censos de avifauna por pontos durante a época de nidificação em oito zonas da cidade de Aveiro, Portugal. A análise de dados realizou-se com recurso a análise descritiva, testes de hipóteses e modelos lineares generalizados. Os resultados indicam que espécies omnívoras como Columba livia e Passer domesticus são espécies dominantes na maioria das zonas de Aveiro. Os resultados mostram ainda que a riqueza específica é mais alta em zonas localizadas a uma maior distância de esplanadas, em ruas com mais movimento e com maiores densidades tanto de árvores como de edifícios mais altos, bem como menor percentagem de impermeabilidade do solo e menor densidade de população humana residente. Adicionalmente, zonas com maior densidade de edifícios mais velhos, mas também de maior altura, menor densidade de população humana residente, com ruas de maior movimento e maior distância a esplanadas, suportam maior abundância de avifauna. Ainda, existe maior diversidade, abundância e biomassa de avifauna no nível médio de altura do que nos níveis baixo e alto. Estes resultados sugerem que a combinação de fatores sociais e de uso do solo locais, em detrimento da aplicação de fatores únicos, permitem uma melhor compreensão da biodiversidade e estruturas espaciais de comunidades de aves urbanas. Adicionalmente, devido à complexidade dos ecossistemas urbanos, é pertinente realçar a relevância de integrar investigadores das ciências sociais e de ordenamento do território em investigações de ecologia urbana.
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Clement, Deanna Marie, and n/a. "Distribution of Hector�s dolphin (Cephalorhynchus hectori) in relation to oceanographic features." University of Otago. Department of Zoology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070221.122411.
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Hector�s dolphin (Cephalorhynchus hectori) is an endangered coastal species endemic to New Zealand. Their distribution, like other marine organisms, is intertwined with the dynamics of their local habitats, and at a larger scale, the coastal waters around New Zealand. The main purpose of this thesis was to identify specific habitat requirements of this rare dolphin.
Hector�s dolphin distribution around the South Island was quantified along several temporal and spatial scales. Large-scale density analyses of abundance surveys found over half of the South Island�s current population occurred within only three main regions. Two of these strongholds are along the west coast and the third is located around Banks Peninsula on the east coast. Smaller-scale analyses at Banks Peninsula found the majority of the dolphin community was preferentially using core regions within the marine mammal sanctuary. Monthly surveys showed that in summer and autumn statistically more dolphins occurred within inshore regions ([less than or equal to]one kilometre), spread throughout the surveyed coastline. From May through winter, dolphin densities rapidly declined. Remaining dolphins were significantly clumped in more offshore waters of eastern regions. The lowest encounter rates occurred between August and September. Certain 'hotspots' consistently had higher dolphin densities throughout the study period while others were preferred seasonally.
To address habitat preferences, surveys simultaneously collected oceanographic samples using a CTD profiler. In general, physical variables of the Peninsula�s eastern and southeastern waters varied less, despite being regularly exposed to upwellings and the varied presence of sub-tropical waters. Semi-sheltered bays and shallow inshore waters were highly variable and more susceptible to spatially discrete influences, such as localised river outflows and exchange events. Several hydrographic features were seasonally predictable due to their dependence on climate. The stratification and location of the two dominant water masses (neritic and sub-tropical) accounted for over half of the temporal and spatial variability observed in oceanographic data.
Possible relationships between oceanographic features and aggregations of dolphins within Banks Peninsula were examined using global regression and a spatial technique known as geographical weighted regression (GWR). GWR models out-performed corresponding global models, despite differences in degrees of freedom and increased model complexity. GWR results found relationships varied over localised scales that were concealed by global methods. Monthly GWR models suggested the seasonal presence and strength of local oceanographic fronts influenced dolphin distribution. Dolphin aggregations coincided with the steepest gradients between water masses along eastern regions of the Peninsula, and strong exchange events along the edges of the study area.
The continued survival of this endangered species is contingent on its protection. Long-term monitoring programmes are needed for the three main strongholds identified in this study. The occurrence of Hector�s dolphin 'hotspots' along frontal zones within Banks Peninsula also suggests alternative and increased protection strategies are needed for this sanctuary to be effective. In light of this thesis� findings and based on marine protection research, future sanctuaries need to consider why Hector�s dolphins are preferentially using particular regions and how their association with certain oceanographic features can help make informed decisions on more appropriate protected areas.
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Markones, Nele [Verfasser]. "Habitat selection of seabirds in a highly dynamic coastal sea : temporal variation and influence of hydrographic features / Nele Markones." Kiel : Universitätsbibliothek Kiel, 2008. http://d-nb.info/1019621605/34.
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Biko’o, AA, Plessis DGC du, and WJ Myburgh. "Population size, structure and habitat features of Haworthia koelmaniorum var. mcmurtryi, an endemic plant from Mpumalanga Province, South Africa." Koedoe, 2011. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000163.
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Haworthia koelmaniorum Oberm. & D.S. Hardy var. mcmurtryi (C.L. Scott) M.B. Bayer is an
endemic plant restricted to the high-lying areas of Mpumalanga Province in South Africa.
There is a serious lack of information on this species; it was known from only two populations
at the time of the study but this information did not include population sizes and structures
or its habitat requirements. A total count was conducted of one of the two populations to
determine its size. Recorded plants were classified into age groups – according to their size
and number of leaves – to determine the population structure. A detailed investigation of
the habitat features of the studied population was also conducted. It was found that the
studied population consisted of 1284 individuals and comprised approximately 4% seedlings,
12% juveniles and 84% mature plants. The species was found to have specialised habitat
requirements, occurring only on red rhyolite of the Selons River Formation. The plants were
also found to select very specific habitat features within their range of occurrence. The species
also seems to be adapted to fire and has developed strategies to survive fire events. It is
recommended that future research projects on this species use the same methods and age
groups as this study to facilitate comparison. It is also recommended that more research be
initiated to determine the population and seed viability, specific pollinators and the optimum
fire frequency and intensity for this species.
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Kuechle, Megan A. "INFLUENCE OF ENVIRONMENTAL FEATURES ON SPERMATOPHORE PLACEMENT IN SPOTTED SALAMANDERS (AMBYSTOMA MACULATUM)." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6113.
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Successful reproduction in salamanders is driven by behavioral, environmental, and temporal interactions among adults. While much of our understanding of salamander mating systems is based upon either courtship behavior of both sexes or aspects of female choice, the decisions made by males regarding where to place spermatophores is much less quantified. In this study, we mapped male spermatophore placement in the spotted salamander (Ambystoma maculatum) with respect to ecological and spatial locations within a vernal pool complex in Charles City County, Virginia. The overall goal was to use the spatial and ecological placement of spermatophores to determine if individuals deposit spermatophores randomly within the vernal pool or if males exhibited specific preferences for deposition. Using comprehensive surveys of the vernal pools and individual spermatophores within a 0.5m2 grid and terrestrial LIDAR, a total of 218 spermatophores were identified and mapped. We repeated these surveys for two successive breeding seasons. Placement occurred at an intermediate depth and an intermediate distance to the edge. Males also preferred to place spermatophores on leaf substrate as opposed to sticks or conifer needles. The physical placement of spermatophores exhibited autocorrelation in space during single reproductive events as well as across breeding seasons. These results suggest that males actively select for specific locations within a pool for spermatophore placement-a proverbial Goldilocks zone-which may be consistent with increased reproductive success. This information is key to understanding salamander mating system parameters in this species and may contribute to developing more effective management strategies.
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Rowe, Christopher Brian. "The influence of habitat features and co-occurring species on puma (Puma concolor) occupancy across eight sites in Belize, Central America." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/82032.
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Large carnivores play many vital biological, economic, and conservation roles, however, their biological traits (low population densities, cryptic behavior) make them difficult to monitor. Pumas have been particularly difficult to study because the lack of distinctive markings on their coats prevents individual identification, precluding mark-recapture and other similar analyses. Further, compared to temperate areas, research on the interspecific interactions of Central American felids is particularly lacking. I used single- and multi-season, single-species occupancy models and two-species co-occurrence models to analyze camera trapping and habitat data collected at eight study sites across Belize. Puma occupancy was positively influenced by jaguar trap success, understory density, canopy cover, and human trap success, and negatively influenced by stream density. Jaguar trap success was the best predictor of where pumas occurred, while prey species were not found to influence puma occupancy. Mean occupancy was 0.740 (0.013) and ranged from 0.587 (0.042) to 0.924 (0.030). Over time, puma occupancy rates were generally high (> 0.90) and stable. Puma occupancy was higher in logged areas, suggesting that current levels of natural resource extraction at those sites were not detrimental to the species. Co-occurrence modeling showed little evidence for interactions between the carnivores, suggesting that jaguars may be acting as an umbrella species and that conservation efforts directed at jaguars are likely to benefit the other carnivores, including pumas. Overall, these findings are positive for puma conservation, but human-induced land use change is expanding and further monitoring will give us insight into how pumas respond to human encroachment.Master of Science
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Nordstrom, Chad Andrew. "Habitat selection by foraging northern fur seals : assessing in-situ ocean temperature and links to Oceanographic features in the Eastern Bering Sea." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42337.
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Habitat characteristics and mechanisms that enable predators to successfully forage are poorly understood in open marine ecosystems. I addressed this problem in the eastern Bering Sea using animal-born data-loggers carried by lactating northern fur seals (Callorhinus ursinus) from two populations breeding in distinct oceanographic zones — a declining population on St. Paul Island on the continental shelf, and an increasing population on Bogoslof Island over the oceanic basin. The data-loggers recorded water temperatures, dive depths and animal locations throughout foraging trips that lasted as long as 17 days and extended as far as 460 km from the islands. I contrasted tag-derived ocean temperatures with concurrent shipboard measurements and found that the fur seal data revealed finer-scale hydrographic processes with less estimated error than ship-derived data, particularly in dynamic oceanographic areas. I also identified probable foraging hotspots using first-passage time analysis of at-sea locations of individual females, and linked them to fine-scale hydrographic data using habitat selection models. I found that hot spots were related to thermoclines and surface fronts (although not with water temperature), and that the relationships differed between populations and among foraging strategies. St. Paul Island fur seals that mixed epipelagic and benthic dives focused their effort in areas with deeper thermoclines that may concentrate prey closer to the ocean floor, while strictly epipelagic foragers tended to use waters with shallower thermoclines allowing prey to migrate closer to the surface. Fur seals from Bogoslof Island foraged almost exclusively over the Bering Sea basin and appeared to hunt intensively along the fine-scale fronts that surrounded the island while fur seals from St. Paul Island extended their trips off-shelf to forage in areas with similar oceanographic features. It appears that lactating females rely on fine-scale boundaries in the open ocean to effectively concentrate prey, and that the relative distribution and accessibility of these oceanographic features account for the inter-island differences in foraging patterns. Collectively, my thesis shows that wide-ranging, diving animals such as fur seals can be used to produce detailed maps of marine habitat and demonstrates the importance of fine-scale habitat characteristics to top predators foraging in dynamic oceanographic environments.
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Barton, Sheri L. "The influence of habitat features on selection and use of a winter refuge by manatees (Trichechus manatus latirostris) in Charlotte Harbor, FL." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001614.
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Barton, Sheri L. "The Influence of Habitat Features on Selection and Use of a Winter Refuge by Manatees (Trichechus manatus latirostris) in Charlotte Harbor, Florida." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3835.
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Investigating alternate winter refuges for Florida manatees is increasingly important
as sustained warm-water discharges from industrial and some natural sites becomes more
uncertain. This study examined habitat features of possible importance to manatees by
comparing a winter refuge in Charlotte Harbor, FL (the Matlacha Isles canal system) to
two nearby, seemingly similar sites that are not frequented by manatees during winter.
Water temperature, salinity, boat traffic, canal depth, and tidal flushing were assessed at
these sites. Additionally, this study examined when and how manatees use the Matlacha
Isles refuge by documenting movements, habitat use, and behaviors of manatees during
the winters of 1999/2000 through 2001/2002. Water temperatures had a profound
influence on manatee selection of Matlacha Isles over the two comparison canal systems.
Matlacha Isles did not experience the sudden drops in water temperature following cold
fronts, extreme low temperatures, or long periods of temperatures below manatees’
reported thermal tolerance of 18-20
oC that were recorded in Matlacha Pass (ambient) and
the two comparison canal systems. Heat retention within Matlacha Isles may be
associated with greater water depth and lower tidal flushing. Salinity and boat traffic did
not seem to influence site selection by manatees. During moderately cold weather,
manatees occupying Matlacha Isles forage at night in nearby Matlacha Pass and return
early in the morning to Matlacha Isles, where they primarily rest all day. Neither tidal
state nor boat traffic levels affected manatee travel patterns into or out of Matlacha Isles.
Manatees may passively thermoregulate in the warmer waters of Matlacha Isles during
the day (when they are inactive) and sustain their body temperatures at night through the
heat generated during traveling to feeding sites and during ingestion (chewing) and
digestion. During extreme or prolonged cold weather, Matlacha Isles provides
inadequate warmth for manatees; during such times, most of them travel to a power plant
on the Orange River, approximately 50 kilometers away. Findings from this study may
inform resource managers as they consider attributes manatees find desirable or
necessary in winter. Such information will help managers create new or enhance existing
winter refuges to protect manatees.
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Bartuszevige, Anne M. "THE INFLUENCE OF HABITAT SUITABILITY, LANDSCAPE STRUCTURE, AND SEED DISPERSERS ON INVASION OF AN EXOTIC PLANT SPECIES, LONICERA MAACKII (RUPR) HERDER, AMUR HONEYSUCKLE." Oxford, Ohio : Miami University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1102952156.
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Bellamy, Stephen, and steve bellamy@flinders edu au. "RESOURCE PARTITIONING BETWEEN TWO SYMPATRIC AUSTRALIAN SKINKS, EGERNIA MULTISCUTATA AND EGERNIA WHITII STEPHEN BELLAMY Thesis submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy AUGUST 2006 SCHOOL OF BIOLOGICAL SCIENCES FLINDERS UNIVERSITY, ADELAIDE, SOUTH AUSTRALIA ________________________________________." Flinders University. Biological Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20070124.145924.
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When species compete for resources, in a stable homogeneous environment, there are two possible outcomes. The first is that one species will out-compete the other and exclude it from the environment. This is known as the competitive exclusion principle. The second is that both species will manage to coexist. Coexistence can only occur if the species niches are differentiated such that interspecific competition is minimised, or eliminated. This outcome is known as resource partitioning.
Two closely related Australian skink species of the Egernia genus, Egernia multiscutata and Egernia whitii, are abundant and sympatric on Wedge Island in South Australias Spencer Gulf. The species are morphologically very similar and appear to have very similar life histories and habitat requirements. Ostensibly, they would compete for limiting resources in this environment.
This thesis is the first investigation into resource partitioning in this previously unstudied model organism. I report the results of multi-faceted investigations into the coexistence of the skinks, E. multiscutata and E. whitii on Wedge Island and the evidence for, and mechanisms of, any facultative resource partitioning between them.
Study methods involved a transect survey of most of Wedge Island to determine the species distributions and any evidence for resource partitioning; a morphological comparison to investigate any potential competitive advantages of either species; a habitat choice experiment to establish retreat-site preferences in the absence of interspecific interference; and, a series of staged dyadic encounter experiments to investigate interspecific competitive interactions.
Resource partitioning was evidenced by differential distributions of the species among substrates containing the elements required for permanent refuge shelters. This partitioning was not mediated by avoidance of particular substrates but by the presence of the opponent species, combined with attraction to suitable substrates. Asymmetries in some morphological characters were found to confer a potential competitive advantage to E. multiscutata in agonistic encounters with E. whitii. Both species were found to have the same refuge site preferences when interference competition was experimentally removed. This result was not concordant with observed resource partitioning in the field and suggests that the habitat choices of both species are modified by the presence of the opponent species. Analyses of staged dyadic encounter experiments showed that E. multiscutata was more likely to gain greater access to a contested habitat resource and more likely to exclude E. whitii from the resource than vice-versa. Nevertheless, the outcome of competitive interactions was not completely deterministic and there was some tolerance of co-habitation. E. multiscutatas competitive advantage was attributable largely to its greater mass and head dimensions relative to snout to vent length. However, differential behavioural responses to the threat of larger opponent size also played an important part in resource partitioning between the species.
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Knight, Tessa. "The use of landscape features and habitats by the lesser horseshoe bat (Rhinolophus hipposideros)." Thesis, University of Bristol, 2006. http://hdl.handle.net/1983/58fd61a7-c564-4f25-b6a7-7d6b6a75ecad.
Full textAbstract:
This study examines the diet and foraging behaviour ofRhinolophus hipposideros from maternity colonies in three contrasting landscapes within Britain. Geographical and seasonal variations in diet and habitat selection exist. .Broadleaved woodlands, water, rural settlements and pastures with wooded edge or unmanaged hedges were generally most utilised and broad-leaved tree cover and edge habitats are likely to be of key importance. The presence of non-volant prey in the diet confirms gleaning, but the majority of prey is probably caught on. the wing during aerial hawking, within or close to the tree canopy. Feeding on swarming insects may play a major part in foraging, with dusk, and to a lesser extent dawn, being important foraging times. The first flying bout was significantly longer in the lowland implying feeding is more efficient in the high quality and upland landscapes. Bats flew for on average 57 % of the night but colder temperatures and increasing rainfall resulted in bats flying for longer. They may aim to reach a target of energy consumption, which takes longer in poorer conditions. An average of 2.1-4.5 night roosting bouts were recorded and R. hipposideros may deviate from the more typical bimodal pattern as their broad diet allows them to feed throughout the night. Night roosts were significantly nearer to core foraging areas than the maternity roost and may form an integral part of the core areas. Foraging density was estimated to be 0.09-0.50 batslha. The ranging behaviour was consistent across the three landscapes. Average home range was 147-177 ha and mean n:taximum distance from the maternity roost waS 2 Ian. It is likely that the bats were adopting an optimal behaviour that is constrained by the species' morphology. The implications of the findings for the species' conservation are discussed and management recommendations are made.
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Abu, Dalou Ahmad Y. "The validity of morphological features and osteological markers in reconstructing habitual activities." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4877.
Full textAbstract:
Thesis (Ph.D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (July 17, 2008) Includes bibliographical references.
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Sarlöv, Herlin Ingrid. "Edge habitats in agricultural landscapes : woody species, landscape ecology and implications for planning /." Alnarp : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5715-7.pdf.
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He, Shi. "From Sleep to Wellbeing: Designing Environmental Features to Avoid Sleep Deprivation." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1593268594944413.
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Westerberg, Lars. "Population processes in heterogenous landscapes /." Linköping : Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/tek897s.pdf.
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Tempera, Fernando. "Benthic habitats of the extended Faial Island Shelf and their relationship to geologic, oceanographic and infralittoral biologic features /." St Andrews, 2008. http://hdl.handle.net/10023/726.
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Tempera, Fernando. "Benthic habitats of the extended Faial Island shelf and their relationship to geologic, oceanographic and infralittoral biologic features." Thesis, University of St Andrews, 2009. http://hdl.handle.net/10023/726.
Full textAbstract:
This thesis presents a new template for multidisciplinary habitat mapping that combines the analyses of seafloor geomorphology, oceanographic proxies and modelling of associated biologic features. High resolution swath bathymetry of the Faial and western Pico shelves is used to present the first state-of-the-art geomorphologic assessment of submerged island shelves in the Azores. Solid seafloor structures are described in previously unreported detail together with associated volcanic, tectonic and erosion processes. The large sedimentary expanses identified in the area are also investigated and the large bedforms identified are discussed in view of new data on the local hydrodynamic conditions. Coarse-sediment zones of types hitherto unreported for volcanic island shelves are described using swath data and in situ imagery together with sub-bottom profiles and grainsize information. The hydrodynamic and geological processes producing these features are discussed. New oceanographic information extracted from satellite imagery is presented including yearly and seasonal sea surface temperature and chlorophyll-a concentration fields. These are used as proxies to understand the spatio-temporal variability of water temperature and primary productivity in the immediate island vicinity. The patterns observed are discussed, including onshore-offshore gradients and the prevalence of colder/more productive waters in the Faial-Pico passage and shelf areas in general. Furthermore, oceanographic proxies for swell exposure and tidal currents are derived from GIS analyses and shallow-water hydrographic modelling. Finally, environmental variables that potentially regulate the distribution of benthic organisms (seafloor nature, depth, slope, sea surface temperature, chlorophyll-a concentration, swell exposure and maximum tidal currents) are brought together and used to develop innovative statistical models of the distribution of six macroalgae taxa dominant in the infralittoral (articulated Corallinaceae, Codium elisabethae, Dictyota spp., Halopteris filicina, Padina pavonica and Zonaria tournefortii). Predictive distributions of these macroalgae are spatialized around Faial island using ordered logistic regression equations and raster fields of the explanatory variables found to be statistically significant. This new approach represents a potentially highly significant step forward in modelling benthic communities not only in the Azores but also in other oceanic island shelves where the management of benthic species and biotopes is critical to preserve ecosystem health.
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Barreiro, Sílvia Pereira. "Saving trees for saving bats: tree-like features as key foraging habitats for insectivorous bats in intensively farmed agricultural lands." Master's thesis, Universidade de Évora, 2016. http://hdl.handle.net/10174/18418.
Full textAbstract:
The loss of natural vegetation remnants and homogenization of agricultural landscapes have
detrimental effects on bat occurrence. As bats are efficient pest controllers, it is important to
understand the mechanisms underlying their persistence in agricultural landscapes. By comparing
structural features of increasing complexity (open fields, single trees, tree lines and woodlands), we
investigated the patterns of bat species richness, flight and feeding activities; and the potential
effect of prey availability on these patterns. Open fields were significantly less bat rich and had
lower levels of flight and feeding activities than treed features, which were differently used by
distinct bat guilds. These differences were not driven by prey availability, which was similar across
structural feature complexity. We conclude that the occurrence of different structural elements
within agricultural landscapes provide a variety of commuting and feeding habitats for bat species
with different requirements, reinforcing the importance of landscape heterogeneity to bat
occurrence and species richness in agricultural landscapes; PRESERVAR ÁRVORES PARA CONSERVAR MORCEGOS: ESTRUTURAS COM ÁRVORES COMO
HABITATS DE ALIMENTAÇÃO CHAVE PARA MORCEGOS INSECTÍVOROS EM ÁREAS DE
AGRICULTURA INTENSIVA.
RESUMO:
A perda de vegetação natural e a homogeneização das paisagens agrícolas tem efeitos negativos na
ocorrência de morcegos. Devido ao importante serviço de controlo de pragas providenciado pelos
morcegos, importa perceber os mecanismos subjacentes à sua persistência nestas paisagens. Neste
estudo investigámos os padrões de riqueza específica e de actividade de voo e alimentação de
morcegos em estruturas de complexidade crescente (campos abertos, árvores isoladas, linhas de
árvores e bosques); assim como o potencial efeito da disponibilidade de alimento sobre esses
mesmos padrões. Os campos abertos apresentaram menor riqueza específica e actividades de voo
e alimentação em comparação com as restantes estruturas, que foram distintamente usadas por
diferentes grupos funcionais. A ocorrência de morcegos não foi influenciada por diferenças de
disponibilidade de alimento entre estruturas. Os resultados da nossa investigação sugerem que
estruturas com distintos graus de complexidade providenciam uma variedade de habitats que
facilitam a deslocação e oferecem oportunidades de alimentação para espécies com diferentes
requisitos, corroborando a importância da heterogeneidade da paisagem para a ocorrência e
riqueza de espécies de morcegos em paisagens agrícolas.
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Roy, Denis. "Time modelled as an explicit feature to quantify habitat quality and preference of chinook salmon, Oncorhynchus tshawyscha, in western Lake Ontario at two time scales, the relative importance of environmental conditions and some implications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ52652.pdf.
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Bon, Cécile. "Stratégies de recherche alimentaire d'un prédateur plongeur en période de reproduction : le Gorfou Macaroni des îles Crozet et Kerguelen." Thesis, La Rochelle, 2016. http://www.theses.fr/2016LAROS004/document.
Full textAbstract:
L’océan Austral abrite encore des populations exceptionnelles de prédateurs marins (manchots, albatros, phoques…). Bien qu’activement étudiés, l’approche fonctionnelle des relations proies-prédateurs souffre encore d’un manque de connaissances chez les prédateurs marins. Etudier comment ces animaux utilisent les habitats est essentiel pour mieux comprendre leur écologie. Par ailleurs, dans une période où les écosystèmes sont soumis à d’importantes pressions d’origine anthropique (surpêche, pollutions, changement climatique), la connaissance de l’écologie d’une espèce est primordiale pour bien caractériser les aires à protéger. Le gorfou macaroni Eudyptes chrysoplophus est un oiseau marin pélagique et constitue l’espèce de manchot la plus abondante dans l’océan Austral (> 6 millions de couples). Au cours des 30 dernières années, les effectifs des populations de Géorgie du Sud et de l’île Marion ont fait face à une diminution drastique (> 30%). Actuellement, les populations de gorfou macaroni des Terres Australes et Antarctiques Françaises (archipel des îles Crozet et îles Kerguelen) abritent encore plus de 50% des effectifs mondiaux. Cependant, les comportements de recherche alimentaire de ces deux populations étaient jusqu’à présent encore mal connues. Au cours de cette thèse, nous avons étudié les stratégies de recherche alimentaire du gorfou macaroni, au cours de l’intégralité de son cycle de reproduction (incubation, élevage et crèche) de Kerguelen et Crozet, îles caractérisées par des environnements océanographiques contrastés. Les ajustements du comportement alimentaire face aux contraintes énergétiques liées à la reproduction et aux variations de la production biologique de leurs environnements ont été examinés en détail. Grace à des mesures biologiques d’origine télémétrique et/ou d’appareil embarqué (trajectoires, comportement de plongées) couplées à des données satellitaires (données environnementales), nous avons pu mettre en évidence l’existence : 1) d’un comportement de recherche alimentaire spécifique et de genre : sur les 2 sites étudiés, un ajustement similaire des déplacements, de l’effort d’approvisionnement, du régime alimentaire a été observé en réponse aux contraintes énergétiques imposées par la reproduction. En incubation, les deux sexes ciblent principalement les fronts océanographiques, les tourbillons et les zones filamentaires situées en eaux pélagiques au cours de longs trajets. En période d’élevage, les femelles s’approvisionnent plus près des côtes, majoritairement sur le plateau et au bord des talus afin de pouvoir alimenter régulièrement la progéniture. En crèche, les mâles ciblent à nouveau les structures frontales tandis que les femelles s’éloignent tout en restant inféodées aux talus. A l’aide de la littérature, nous avons pu observer que cette stratégie semble opérer à l’échelle de l’aire de répartition de l’espèce. 2) d’une plasticité phénotypique inattendue : l’approche comparative entre les îles Kerguelen et Crozet a permis d’étudier les points communs et les différences des stratégies d’approvisionnement entre les deux localités, liées aux conditions environnementales locales. Les deux populations semblent toutes deux très dépendantes des pics saisonniers de productivité primaire. En revanche, des variations d’éloignements à la colonie inter - site et intra – sexe plus importantes qu’attendues ont été observées mettant en évidence une flexibilité phénotypique insoupçonnée pour un prédateur marin pélagique. Cette étude est l’une des rares ayant couvert l’ensemble d’un cycle de reproduction chez les manchots. L’importante variabilité comportementale démontrée réitère le besoin impératif de prendre en compte l’intégralité d’un cycle pour mieux comprendre et définir les stratégies d’approvisionnement d’une espèceThe Austral Ocean still hosts a great population of marine predators (i.e. penguins, albatross, and seals). Despite well studied, the functional approach investigating the relationship between prey and predators in the marine ecosystem is still poorly known. Knowledge on habitat selection and use of marine species is essential to better understand their ecology and behaviour. The knowledge about the ecology of key species is essential to characterise and identify the areas to protect and to predict the future of populations that may be affected by global changes. This is particularly true in an area where the natural ecosystems are more and more perturbed by anthropogenic activities (i.e. over-fishing, pollution, and climate change). The Macaroni penguin is the most abundant penguin species in the Austral Ocean (> 6 millions pairs). It is also the biggest consumer of secondary resources, in terms of biomass, in the world. Over the past 30 years the Macaroni penguin populations situated in South Georgia and Marion Island suffered of 30% population decline. At the moment, Kerguelen and Crozet Islands (French Southern Territories) still host more than 50% of their global population, however the foraging behaviour of this species is still poorly known. The objective of this research is to study the different foraging behaviour strategies of a pelagic seabird : the Macaroni penguin Eudyptes chrysoplophus during its whole breeding cycle (incubation, brood, crèche). The populations’object of study breed in different oceanographic conditions : the Kerguelen and Crozet archipelagos. The variation in foraging behaviour driven by energetic constraints, which is associated to the reproduction and to the biological production, has been studied in details. Telemetry data (i e. trajectories and diving behaviour) combined with environmental data obtained by remote sensing allowed determining that : 1) Foraging strategies of Macaroni penguin breeding in two different locations differ in terms of movement, foraging effort and foraging niche during their breeding cycle in response to reproduction constraints. In incubation, both sexes carried out long journeys and targeted large oceanographic structures such as fronts, eddy and transport fronts. During the brooding phase, the females foraged closer to the colony adjusting their foraging behaviour based on their offspring needs, targeting the shelf and the slope. When crèche started, males targeted large scale structures whereas females still foraged on the slope. At this time, a shift in the diet composition was observed. 2) The comparative approach between Kerguelen and Crozet allowed to highlighting differences in foraging strategies, in response to local environmental conditions. However, greater than expected variations in foraging areas were observed inter-site and inter-sex. These results have pointed out an unexpected phenotypic flexibility for a pelagic marine predator. This research investigated the entire breeding cycle of a penguin, a fact still rare in ecology. The observed degree of behavioural variability reiterates the imperative to take into account an entire cycle to better understand and define the foraging strategies of a species
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Thorne, Lesley Helen. "Seabird foraging in dynamic oceanographic features." Diss., 2010. http://hdl.handle.net/10161/3141.
Full textAbstract:
Oceanographic features, such as fronts, eddies, and upwellings, provide important foraging areas for marine predators. These areas serve as important "hotspots" of marine life, by aggregating weakly swimming lower and mid-trophic level species which, in turn, attract foraging predators. Despite the importance of these dynamic features, we lack a comprehensive understanding of how they create foraging habitat for seabirds and other marine predators. In the first part of this dissertation, I review current knowledge of how seabirds use oceanographic features with an emphasis on developing a more mechanistic understanding of these features, and identify important considerations for future studies. I use the findings of this review to inform two field research projects in the Bay of Fundy, Canada and Onslow Bay, North Carolina. In these two projects, I examined seabird abundance and distribution in relation to oceanographic features that occur at different spatial and temporal scales. In the first project, I examined foraging habitat of red-necked phalaropes (
Dissertation
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Yeh, Chien-Cheng, and 葉建成. "Fauna, distribution and habitat features of Cetaceans in coastal waters of Southeastern Taiwan." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/05643513746254753869.
Full textAbstract:
碩士國立臺灣大學
動物學研究所
89
A boat-based survey was conducted to investigate the fauna, distribution and habitat features of cetaceans in coastal waters of Southeast Taiwan from April 1997 to August 1999. Two survey methods were used: sixty-two days of non line-transect survey were performed from April 1997 to July 1998 and sixty days of line-transect survey were conducted systematically from May 1998 to August 1999. The estimation of sighting rates was based on the data collected from line-transect survey. Relationships between sighted species and its surrounding oceanographic environmental variables were also analyzed. There were five species before this study, and this study found another fourteen species. Combined with all literature records, there are at least twenty species in this area. Fourteen cetacean species were identified in this study. The six most common sighted species were: Grampus griseus, Stenella longirostris, Stenella attenuata, Tursiops truncatus, Lagenodelphis hosei and Feresa attenuata. The records of Physeter macrocephalus and tropical bottlenose whale obtained from fisherman report. The tropical bottlenose whale is a new record in Taiwan. Total on effort of line-transect survey was 4662.4 km and 75 sightings were recorded. The average sighting rate was 1.61 sightings/100km. Between-year comparison of sighting rates during the period of May and August showed no significant difference between 1998(1.93 sightings/100 km) and 1999(1.28). Among-area comparison of sighting rates were no significant difference among the A region(2.15 sightings/100km), the B region(0.89), the C region(2.05) and the D region(1.57). The occurrence of all the six most common sighted cetaceans was not significantly associated with its surrounding sea surface temperature, but was significantly associated with (1) its distance away from the land, and (2) the water depth. For example, sightings of S. longirostris were consistently occurred in the shallowest water, while F. attenuata were found in the deepest water. The result suggests the existence of habitat partition between these most common sighted cetaceans.
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Khachane, Amit Neelkanth. "Towards the elucidation of habitat specific features in prokaryotic genomes using in silico approaches /." 2007. http://www.gbv.de/dms/bs/toc/531235009.pdf.
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Mason, Doris A. Ferreri C. Paola. "Influence of stream channel morphology, stream habitat, and landscape features on brook trout densities in central Pennsylvania Streams." 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-4386/index.html.
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Melles, Stephanie J. "Effects of landscape and local habitat features on bird communities : a study of an urban gradient in Greater Vancouver." Thesis, 2000. http://hdl.handle.net/2429/11398.
Full textAbstract:
Bird species diversity and abundance trends in urban areas can provide evidence to predict
the relative importance of local bird habitat under different landscape contexts. I examined the
hypothesis that selected species and nesting guilds should be more closely associated with
landscape level features, such as proximity to large forested areas (< 100 ha), than with local
scale habitat measures (< 1 ha). I collected avian community data during surveys completed
over a two year period at 285 point count stations along four linear road transects located in
Vancouver and Burnaby, British Columbia. Stations were located along transects bisecting three
large parks (>324 ha) and proceeding away from these parks along residential streets into highly
urban and suburban areas. A total of 49 breeding bird species were observed including 36
common species and 13 species that were sighted only once. Canonical correspondence analysis
was used to view the main associations between measured habitat variables and species
distributions. Species richness declined with increasing urbanization and the gradient (CCA axis
one site scores) was dominated by landscape level habitat measures. Park area-by-distance
metrics, developed using G.I.S., had the highest correlation with CCA axis one indicating the
importance of park area in the vicinity for many species of birds breeding in marginal residential
areas. Different land use zones did not neatly separate the urbanization gradient into simple bird
habitat categories. Habitat models were created for five nesting guilds and three selected species
(Song Sparrow, Melospiza melodia, Spotted Towhee, Pipilo maculatus, and American Robin,
Turdus migratorius) with sequential block addition of landscape and local variables. Local
variables significantly improved predictability of landscape variable only models, but the
difference was slight. Landscape variables alone were often good predictors of presence or
absence of most groups of species (guilds), but were less sensitive than local variables at
predicting individual species presence. Incidence (percent stations occupied) of several bird
species increased with park area in the vicinity as an inverse function of distance. The results of
this study suggest that matrix areas surrounding parks and reserves should be integrated into
urban planning and development designs.
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Hopcraft, J. Grant C. "The effects of habitat features and prey density on the hunting and scavenging success of Serengeti lions (Panthera leo)." Thesis, 2002. http://hdl.handle.net/2429/13978.
Full textAbstract:
This thesis addresses the question of whether Serengeti lions choose foraging sites that facilitate the capture of prey, or whether they choose foraging sites where prey are most abundant. The alternate choices between good habitats and high prey densities have rarely been addressed in resource selection studies of predators. The observed distributions of kills and scavenges by lions were compared to the predictions of two alternate hypotheses; (a) if lions forage in areas that facilitate the capture of prey, such as areas with cover, then more kills and scavenges should occur in these areas than expected. Conversely, (b) if lions forage in areas with high prey densities, and prey avoid risky habitats, then most of kills and scavenges should occur in areas with reduced cover. The hypotheses were tested by comparing the use and availability to lions of 5 habitat types: viewsheds from kopjes, river confluences, erosion embankments, woody vegetation, and sites with access to free water. The amount of each habitat type available was estimated from maps created by GIS analyses and ground truthing, and were tested with univariate, goodness of fit, exact tests as well as multivariate resource selection functions. The results indicate that on the large scale lions move according to the distribution of prey. However, at a finer scale lions select areas that facilitate foraging over areas with high prey densities. Plains and woodland lions selected different habitats depending on season. However, the most important habitats that were selected by both plains and woodland lions for either hunting or scavenging were, river confluences, eroded areas, and areas with water nearby. Viewsheds from kopjes and areas with woody vegetation were also selected, but were not as important. Furthermore, areas with vegetation associated with confluences, vegetation associated with water, and eroded sites associated with water were preferred for foraging more often than predicted. Therefore, the major finding from this study is that although lions require adequate prey for survival, the habitat features available to them for hunting and scavenging are more important than simple prey densities.
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Paczek, Susan. "Effects of fine-scale and landscape-level habitat features on a sagebrush breeding birds of the southern Okanagan and Similkameen Valleys, British Columbia." Thesis, 2002. http://hdl.handle.net/2429/12151.
Full textAbstract:
I determined habitat associations for five species of songbirds breeding in sagebrush of the
southern Okanagan and Similkameen Valleys, British Columbia. I examined the relative
importance of scale for the presence and relative abundance of these species, through the
measurement of vegetation floristics and structure at a local level (<100 m), and habitat context
at three landscape scales (500 m, 1 km and 2 km). Vegetation and bird survey data were
collected at 245 point count stations in 1998. Local-level habitat variables were derived from
field surveys, while landscape-level variation was classified from a single Landsat Thematic
Mapper ( TM ) image from 1996. Within sagebrush habitat the Landsat TM image was also
classified at a fine-scale to determine if local-level habitat variation could be mapped by satellite
data. Accuracy of the classification was assessed in 1999 by ground-truthing. Overall accuracy
was 85%, and 78% for the sagebrush 'subtypes'. Local-level models from Landsat TM
classified sagebrush habitat subtypes agreed with habitat associations identified from vegetation
survey data, indicating that satellite data may be used as a surrogate for field data, although these
associations were relatively weak. Performance of local, landscape, and local + landscape-level
models was assessed from ranked Akaike's Information Criteria (AIC) scores. For all songbird
species, logistic regression models showed the strongest habitat associations at a local level.
Floristic variables were often more important than vegetation structure variables. Brewer's
Sparrow was associated with large tufted perennials: parsnip-flowered buckwheat (Eriogonum
heracleoides) and lupine (Lupinus sericeus or sulphureus). Lark Sparrow was positively
associated with sand dropseed grass (Sporobolus cryptandrus), Vesper Sparrow (Pooecetes
gramineus) was positively associated with lupines, and Western Meadowlark was positively
associated with needle-and-thread grass (Stipa comatd). The addition of landscape-level
variables usually improved the predictive ability of survey-derived local habitat association
models. Habitat associations varied markedly for each species, and songbird relative abundance
responded differently to the scale of measurements. Herb layer species identified as important in
habitat associations were in turn correlated with rangeland management practices. Management
recommendations are presented to direct conservation efforts in this highly threatened area.
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Untiedt, Candice Bobby. "Community structure and function of macrobenthos in three feature areas of the Natal Bight, South Africa." Thesis, 2013. http://hdl.handle.net/10413/10978.
Full textAbstract:
The Natal Bight off the east coast of South Africa is a unique shelf habitat, exhibiting high secondary productivity and supporting high diversity. Ecosystem attributes are influenced by local oceanographic features and outwelling via one of the largest rivers in the country. This study forms part of a larger, multi-institutional, multi-disciplinary study under the second phase of the African Coelacanth Ecosystem Programme (ACEP II) Natal Bight Project, investigating how material sources, posited to be derived from these features, shape the ecological structure and functioning of the region. Macrobenthic samples were collected along cross shelf transects off Richard’s Bay, Durban and the Thukela River mouth during two cruises, corresponding with periods of variable rainfall. Macrobenthic communities were classified taxonomically, to the lowest level possible, and functionally. Community patterns were investigated within and between feature areas and related to measurable environmental factors in order to determine environmental drivers and assess the importance of identified oceanographic features. Environmental parameters measured included sedimentary characteristics as well as physico-chemical conditions in the surrounding pelagic milieu. A total of 38 215 individuals belonging to 826 taxa were recorded from the three feature areas, of which the majority were Polychaeta and Crustacea. An in-depth investigation of the polychaete component has shown that this group can be used as a proxy for the whole macrobenthic community which has important implications for future studies. Facultative feeding modes dominated the trophic functioning macrobenthic communities sampled on the Natal Bight. Primary community metrics of abundance and numbers of macrobenthic taxa were reduced from the high to low rainfall period but differences were not significant, probably due to the lack of temporal repetition. The Thukela feature area was found to support the most abundant and taxon rich macrobenthic community. Mid-shelf stations sampled along the Thukela and Durban transects were in close proximity to the coarse paleo-dune cordon, running along the 60 m isobath and supported a diverse assemblage. Despite the lack of temporal repetition in the present study, there were significant short-term changes in the structure and functioning of macrobenthic communities on the Thukela shelf. This suggests that Thukela River outflow has a significant effect on the functioning of the Natal Bight ecosystem. This was surprising given the importance which has previously been placed on the Cape St. Lucia upwelling cell in terms of contributing nutrients and sustaining biological productivity and diversity on the Natal Bight.Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.