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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.
41

Raptor and wading bird migration in Veracruz, Mexico spatial and temporal dynamics, flight performance, and monitoring applications /

Ruelas Inzunza, Ernesto, January 2007 (has links)
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 (viewed on October 9, 2007) Vita. Includes bibliographical references.
42

Foraging ecology of Cape Gannets (Morus Capensis) at Bird Island, Algoa Bay

Green, David Bruce January 2013 (has links)
The Cape gannet has undergone considerable population change and redistribution over the past 50 years. This has been linked to shifts in the abundance and distribution of their dominant prey, sardine and anchovy. Five breeding colonies, along the west coast of Southern Africa, have shown rapid population declines as a result of reduced prey availability. In contrast, a single colony (Bird Island, Algoa Bay) on the south coast of South Africa has, over the same period, grown fivefold and now supports approximately two thirds of the total population. Due to its conservation importance, and isolation from other breeding localities, it is important to assess the health of the Bird Island colony, and determine how foraging distribution relates to the environment to evaluate current measures of protection. This was achieved through two related studies; a long-term dietary analysis spanning 34 years, and a spatial foraging study, which related three years of tracking data to estimates of prey availability, oceanographic features and marine protected areas (MPAs). The results of the dietary study showed that the dietary constituents of Cape gannets breeding at Bird Island have remained similar over the last three decades, but the importance of sardine and anchovy has increased significantly. For sardine, in particular, this reflects an increased availability of this species (as deduced from hydroacoustic surveys) within the foraging range of the Bird Island colony. The dietary abundance of anchovy was found to be negatively correlated with that of sardine. Surprisingly,.the dietary abundance of anchovy was also negatively correlated with estimates of its availability based on acoustic surveys. The latter is likely to be due to sardine being a preferred prey item. Recent decreases in the dietary contribution of sardine (since 2005) suggest that this species is becoming less available to gannets, with profound implications in terms of nutrient gain associated with foraging. However, this has been mediated by an increase in the dietary contribution of anchovy, which now accounts for the vast majority of prey taken. Spatially, the foraging range of the Bird Island colony expanded during the three years of study, indicating an increase in effort. This increase was likely in an effort to track a distributional change of sardine and anchovy, which showed an apparent westward shift during the study period. There was, however, no evidence of birds tracking features associated with high productivity. This may have been partly due to anomalously warm conditions during the summer of 2012/2013, in which an absence of coastal upwelling prevented surface cooling. Nonetheless, low sea surface temperatures and high chlorophyll a concentrations do not seem to be reliable indicators of important Cape gannet foragingareas. Foraging effort was largely concentrated outside of MPAs, indicating that the current MPA network provides little protection for foraging gannets. This could change with the additional protection of the proposed Greater Addo Elephant National Park MPA expansion, as prey species are allowed to recover following the removal of fishing pressure. Overall, the colony appears to be in good condition as the diet is still dominated by live prey items, and the foraging range remains smaller than many of the colonies along the west coast. However, it is important that monitoring be continued, in particular with respect to changes in the availability of sardine and anchovy. Long-term shifts of these species out of the colony‘s foraging range could negatively influence the population in the future. This might be worsened by interspecific competition for prey resources. Considering the conservation importance of this population, maintenance of healthy prey stocks within the home range of breeding Cape gannets should be prioritised in order to prevent declines similar to those observed at west coast colonies.
43

Time-activity budgets of cape gannets (Morus Capensis) at Bird Island, Algoa Bay

Rishworth, Gavin Midgley January 2014 (has links)
For several decades now, seabirds have been considered to be useful indicators of the state of their prey resources because of how they reflect lower-level trophic variability through proxies such as diet or behaviour. However, collection of appropriate data is often challenging in the marine environment because of logistical or financial constraints. In this study, time-activity budgets were studied in the Cape gannet (Morus capensis), a seabird which has been advocated as a potential bioindicator for local epipelagic prey. VHF transmitters attached to PVC leg-rings were fitted to 50 adult breeding pairs during the 2011/2012 and 2012/2013 breeding seasons at Bird Island, Algoa Bay, to determine whether an automated method of continuously collecting time-activity budget data can replace conventional laborious direct observations. To validate that the foraging trip duration data generated from the automated method was a reflection of foraging effort, Time-Depth Recorders (TDRs) were simultaneously equipped to birds with VHF transmitters for three weeks. In order to assess the influence of factors other than prey availability on parent time-activity budgets, sex, chick age and body condition were measured. Additionally, chick growth and survival were recorded in order to investigate the gender-specific effects of parental time-activity budget variability on these parameters. Attachment of VHF transmitters to leg-rings of adult Cape gannets had no observable negative effects on the adults or their chicks in terms of adult body condition, nest attendance and foraging trip durations, or chick growth and survival. Furthermore, the frequency distribution of behaviour bout (foraging trip and nest attendance) durations was no different between automated and directly observed data. However, the automated method did record shorter behaviour bouts, largely attributed to the increased likelihood of direct observations missing birds returning briefly to their nests during older chick provisioning. Additionally, foraging trip duration was highly correlated to foraging effort in terms of time spent resting on the sea surface, flying and diving. The automated method therefore appears to be a good reflection of direct nest attendance observations and foraging effort. Cape gannet time-activity budgets were related to chick age and parental sex. Especially as chicks neared fledging, females spent significantly longer periods of time foraging than males, with males consequently provisioning their chicks more often. Furthermore, adults departing their nests earlier spent more time away from the nest foraging as more same-day daylight hours were available. Chick growth was a function of parent foraging trip duration and associated prey delivery rates. Chick survival was most strongly affected by the amount of time which chicks were left unattended by both parents and consequently exposed to predation by kelp gulls (Larus dominicanus) or to adverse weather conditions. Additionally, for females (but not males) there appeared to be a trade-off between foraging trip duration and chick survival. The Cape gannet appears to demonstrate a strategy whereby the costs of reproduction to the female are shifted towards male-dominated chick provisioning as the chick nears fledging. Drivers of time-activity budget variability such as chick age and parental sex therefore need to be considered if using data on foraging trip duration as a proxy of foraging effort and prey availability.
44

Avaliação dos valores bromatológicos de camundongos (Mus musculus)

Barbosa, Luiz Gustavo Bicas January 2020 (has links)
Orientador: Carlos Roberto Teixeira / Resumo: Os camundongos (Mus musculus) atualmente compõem a base alimentar de diversas espécies animais, tanto mamíferos como aves e répteis. tendo assim certa importância para o manejo nutricional de animais de vida livre que necessitam de tratamento, por acidentes, tráfico, animais cativos em zoológicos e centros e triagens, e animais que são comercializados como pets exóticos. Este trabalho teve por objetivo fornecer uma base de informações de dieta em relação às necessidades nutricionais de animais que se alimentam de camundongos. Foi comparado o conteúdo nutricional de quatro grupos (G1, G2, G3, G4) de camundongos diferenciados por origem e tempo de congelamento. Cada grupo gerou um pool do qual mediu-se a composição centesimal (umidade, lipídios, proteínas, cinzas), calorimetria, os minerais: Sódio (Na), Potássio (K), Cálcio (Ca), Magnésio (Mg), Fósforo (P), Ferro (Fe), Manganês (Mn), Cobre (Cu), Selênio (Se), e Zinco (Zn) e feito o perfil de ácidos graxos. Observou-se diferença estatística quando a umidade e proteínas, e quanto a amostra in natura sem congelamento quando comparada com as amostras in natura congeladas. Os resultados apresentaram uma variação (p<0,001) entre os animais provindo de biotérios e de fonte comercial, mostrando divergência no padrão de qualidade, determinando pouca confiança dos valores nutricionais de animais adquiridos congelados de fonte comercial. / Abstract: Mice (Mus musculus) currently make up a food base for several animal species, both mammals, birds and reptiles. having the same importance for the nutritional management of free-living animals that can be treated, by accidents, trafficking, captive animals in zoos and centers and screens, and animals that are marketed as exotic pets. This work aimed to provide a base of information on diet in relation to the nutritional needs of animals that feed on mice. It was compared or nutritional content of four groups (G1, G2, G3, G4) of mice differentiated by origin and freezing time. Each group generated a pool of which type of chemical composition (composition, lipids, proteins, ash), calorimetry and minerals: Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg), Phosphorus (P), Iron (Fe), Manganese (Mn), Copper (Cu), Selenium (Se), and Zinc (Zn) and fat profile or profile. Observe the statistical difference when a molecule and proteins and how much a fresh sample are compared to frozen samples. The results showed a variation (p <0.001) between animals that come from biotechnology and commercial sources, showing divergence in the quality standard, determining little confidence in the nutritional values of animals purchased frozen from commercial sources. / Mestre
45

Mathematical models of a tick borne disease in a British game bird with potential management strategies

Porter, Rosalyn January 2011 (has links)
Louping ill virus (LIV) is a tick borne disease that causes mortality in red grouse, an economically important game bird of British uplands. The aim of this thesis is to extend previously published models of LIV , to consider the potential impact of different management strategies. In addition a new route of infection and the seasonal biology of both grouse and ticks will be explored. Grouse chicks are known to eat ticks as part of their diet in the first three weeks of life which may contribute to virus persistence if chicks consume infected ticks. This novel route of infection is incorporated in to the model which predicts that ingestion increases the range of host densities for which the virus is able to persist. The ingestion of ticks by grouse also reduces the tick population so that for low host densities the ingestion of ticks by grouse reduces the tick population so virus cannot persist. The model is adapted to take account of the seasonal biology of grouse and ticks. Although the temporal predictions of the seasonal models show some differences the addition of seasonality does not alter the model predictions of when LIV is likely to persist at different grouse and deer densities. Consequently seasonality is felt to be unimportant when considering management strategies. The treatment of sheep with acaricide in an attempt to reduce the tick population on a grouse moor is currently being trialled in Scotland. We use a model to predict the likely effect of this strategy at different deer densities. The number of ticks found attached to sheep varies so we consider the effect of tick attachment rates as well as acaricide efficacy. Although we predict that acaricide treated sheep can reduce the tick population and therefore LIV in grouse in some circumstances the treatment is less effective in the presence of deer. Consequently we use a model to make theoretical predictions of the effectiveness of acaricide treated deer as a control strategy for reducing LIV in red grouse. The effect of culling deer on LIV in grouse is also modelled and contrasted with the effect of acaricide use. It is predicted that acaricide treatment of deer could be highly effective, particularly if the deer density is first reduced by culling. Finally we considered the direct treatment of red grouse with acaricide. Female grouse can be given an acaricidal leg band which protects her directly and indirectly protects her chicks as they acquire some acaricide whilst brooding. Trials have suggested this can reduce tick burdens for individuals. We use the model to determine the potential effect that treating individual broods may have on the whole grouse population. The model predictions suggest that unless acaricide efficacy on chicks is high and long lasting treating individual broods is unlikely to reduce LIV in the whole population but will still provide some benefit for the individuals. The effectiveness of treatment is reduced by higher deer densities. The success of the management strategies considered in this thesis appear to be restricted by the presence of deer. It may therefore be that a combination of treatments including the treatment of deer may be of the greatest benefit to the grouse population.
46

Factors que afecten l’èxit d’expansió de poblacions d’aus en medis transformats per l’home: l’arpella "Circus aeruginosus" a la Vall de l’Ebre Factors affecting expansion success of bird populations in human-transformed environments: the marsh harrier Circus aeruginosus in the Ebro Valley

Cardador Bergua, Laura 07 October 2011 (has links)
Change in species geographic ranges is a natural phenomenon, but the rate and magnitude of such change has significantly increased due to anthropogenic causes. The rate at which a population spreads/contracts through space is a function of the rates of population growth and dispersal, coupled with density-dependence. Human-induced environmental changes can lead to variation in density-independent components of local birth or death rates through deterministic process (e.g. impoverishment/increase of habitat and food resources), thus pushing populations toward positive/negative growth. Moreover, spatial range constraints, such as dispersal, and density-dependence may also limit population growth and range expansion, beyond environmental characteristics. The main goal of this thesis is to explore the role played by ecological factors such as habitat and food availability, spatial range constraints and density-dependence in the expansion of a species through human-transformed environments. For this purpose, I use as a study model an expanding population of the marsh harrier living in an agricultural landscape of the Ebro Valley (northeastern peninsular Spain). Results obtained in this thesis suggest that environmental factors, sociability, dispersal constraints and density-dependent mechanisms may play an important role in the distribution of a species. Marsh harrier breeding numbers had been greatly reduced in previous decades (1960-1980) mainly due to organochlorine pesticides, drainage of wetlands and direct persecution. Thus, at least part of their increase in recent decades may represent population recovery following reductions in organochlorine use and direct persecution. However, the species may also have benefited from the spread of human-made structures such as artificial ponds and reservoirs related to agricultural intensification, for breeding and from their surrounding herbaceous crops for hunting. At a local scale, individual variation in density-dependence for productivity and settlement patterns may have favoured dispersal of some individuals to new empty habitat patches, while others aggregated around traditional areas. However, at a large scale (i.e., across peninsular Spain), the breeding population of marsh harriers seems to be spatially constricted beyond environmental variables. This result indicates that potential habitat for marsh harriers still exists for further expansions in the Iberian Peninsula (at least at the spatial resolution of our analyses, which does not allow us to consider smaller scale processes that may restrict the species distribution such as local food abundances or pesticides). Potential consequences of this expansion for other species should be considered in order to properly conserve biodiversity in a world of change. / En aquesta tesi s’analitza el paper que desenvolupen factors ecològics com l’hàbitat i la disponibilitat d’aliments, les limitacions espacials i la denso-dependència en l’expansió d’una espècie en ambients transformats per l’home. S’utilitza com a model d’estudi l’arpella Circus aeruginosus en una zona agrícola de la Península Ibèrica, a la part oriental de la Vall de l’Ebre. Els resultats d’aquesta tesi indiquen que tant els factors ambientals, de sociabilitat, les limitacions dispersives i els mecanismes de denso-depèndecia poden jugar un paper important en la distribució d’una espècie. La població d’arpella s’havia reduït en dècades anteriors (1960-0980) degut principalment a l’assecament i contaminació de les zones humides on criava, a l’ús de pesticides i a la persecució directa per part de l’home. Si bé, part de l’augment que la població ha experimentat en els darrers anys podria ser degut a la recuperació de la seva població després de la reducció en l’ús d’organoclorats i en la seva persecució per part d l’home, l’espècie també s’hauria beneficiat en els darrers anys de l’increment d’estructures artificials, com embassaments i basses de reg artificials relacionades amb l’agricultura, e l’espècie utilitza per nidificar i dels cultius herbacis del voltant per caçar. A escala local, la variació individual en els efectes de la denso-dependència en la productivitat i patrons d’assentament, podrien haver afavorit la dispersió d’alguns individus a noves localitats buides, mentre altres individus amb una resposta diferent a la densitat s’agregaven al voltant de zones ja ocupades. A escala de la Península Ibèrica, l’àrea de distribució de l’arpella encara es veuria limitada, per factors espacials diferents al clima i al tipus d’hàbitat, indicant que encara hi hauria hàbitat potencial per a l’espècie (com a mínim a la resolució espacial de les nostres anàlisi, que no permeten considerar processos a escala local). Les possibles conseqüències de l’expansió d’aquesta i altres espècies haurien de ser considerades per tal de conservar adequadament la biodiversitat en l’actual escenari de canvi global.
47

Hunting area preference of raptors in range lands

Anderson, Jane Elizabeth January 1982 (has links)
No description available.
48

Farmland birds in semi-natural pastures : conservation and management /

Söderström, Bo, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.
49

Efeitos do fogo sobre assembleias de aves de cerrado / Fire effects on the bird assemblages of cerrado

Reis, Matheus Gonçalves dos 27 March 2015 (has links)
Submitted by Livia Mello (liviacmello@yahoo.com.br) on 2016-09-15T12:31:35Z No. of bitstreams: 1 TeseMGR.pdf: 2131208 bytes, checksum: b36415a6c84dfe47d1989b5ba8da4dcd (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-21T18:29:13Z (GMT) No. of bitstreams: 1 TeseMGR.pdf: 2131208 bytes, checksum: b36415a6c84dfe47d1989b5ba8da4dcd (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-21T18:29:21Z (GMT) No. of bitstreams: 1 TeseMGR.pdf: 2131208 bytes, checksum: b36415a6c84dfe47d1989b5ba8da4dcd (MD5) / Made available in DSpace on 2016-09-21T18:29:27Z (GMT). No. of bitstreams: 1 TeseMGR.pdf: 2131208 bytes, checksum: b36415a6c84dfe47d1989b5ba8da4dcd (MD5) Previous issue date: 2015-03-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fire is an ecological factor which seasonally affects fire-prone ecosystems, such as grasslands and open savannas of the Cerrado, and changes some patterns of the biota. This study aimed to investigate the influence of fire on birds that directly use food resources in grasslands of the Serra da Canastra National Park. From December 2012 to January 2015, sampling efforts were carried out in areas burned by wildfires, prescribed burnings (environmental management strategy) and in areas with no influence of fire, in order to record birds in foraging activities, their diet and the use of microhabitat for foraging. The 92 bird species recorded throughout the study exhibited specific results of the occurrence, abundance and response to fire. Considering all birds, the wildfires exerted a deeper and longer (3 - 4 months) influence on assemblage structure, than the prescribed burnings (2 - 3 months). The fire effects on some species of birds were observed in the proportion of food categories consumed, in the diversity of diet items and the microhabitats selected for foraging. The fire response models for birds of prey that occupy the top of the food chain in grasslands indicated a more intense use of food resources in the first post-fire months. Environmental management towards the conservation of grassland ecosystems depends on understanding the effects of recurrent disturbances on native species. / O fogo é um fator ecológico sazonal de ecossistemas pirofíticos, como os campos e savanas abertas do Cerrado, que altera as características do meio biótico. O presente estudo objetivou investigar a influência do fogo nas aves que forrageiam nos campos do Parque Nacional da Serra da Canastra. Entre dezembro de 2012 e janeiro de 2015, foram amostradas áreas atingidas por fogo natural, por queimadas prescritas (para manejo) e também áreas sem influência do fogo, para monitorar as aves que fazem uso direto de recursos alimentares, a dieta e seus micro-habitats de forrageamento. Foram registradas 92 espécies em todo o estudo, com diferentes resultados específicos de ocorrência, abundância e resposta às queimadas. O fogo natural exerceu influência mais profunda e de maior duração (3 - 4 meses) na estrutura das assembleias, do que as queimadas prescritas (2 - 3 meses). Para algumas espécies de aves, os efeitos das queimadas incluíram variação da proporção de tipos de alimentos consumidos, ampliação da diversidade de itens da dieta e alterações de micro- habitats preferenciais de forrageamento. Com relação às aves que ocupam o topo de cadeia alimentar, os modelos de resposta ao fogo apontam para um melhor aproveitamento de recursos alimentares nos primeiros meses pós-fogo. O manejo ambiental para a conservação de ecossistemas campestres depende da compreensão dos efeitos de distúrbios recorrentes na fauna. / CNPq: 141653/2011-6
50

"This Is a Forced Feminist Agenda" : IMDb users and their understanding of feminism negotiated in the reviews of superheroine films

Budirska, Alzbeta January 2021 (has links)
The thesis examines how users of the Internet Movie Database (IMDb) negotiate feminism in their reviews of four superheroine films – Wonder Woman, Captain Marvel, Birds of Prey: The Fantabulous Emancipation of One Harley Quinn, and Wonder Woman 1984. By combining critical discourse analysis with methods of corpus linguists, this corpus-based study of over 18,000 reviews analyses the frequency of the topic of feminism in the reviews, words and topics associated with it and the way the reviewers reflect broader mediated discourse over the four films, and the role of IMDb as a space for these reviews. The findings show that feminism is still understood as an anti-male movement where female-led films are shielded from criticism by the mainstream media by the virtue of the lead’s gender, the superheroines are criticised for being overpowered particularly where they have no equal male supporting character and that perceived feminist messaging is usually written off as a forced political agenda or as an insincere cash grab made by corporates which effectively use feminism for promotion. It also reveals IMDb as a highly polarised platform where the users leaving 1- and 10-star reviews are generalized as representatives of different sides of the political spectrum (antifeminist vs feminist, conservative vs liberal) regardless of the actual content of the review.

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