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Environmental and ecological determinants of urban bird community structure
Ferenc, Michal ; Sedláček, Ondřej (advisor) ; Lososová, Zdeňka (referee) ; Tryjanowski, Piotr (referee)
The urban environment has attracted much scientific attention as it stands at the core of environmental changes caused by the growing human population. The responses of bird communities to urbanization have been especially frequently studied. Despite the intensive research, there are several unresolved questions resonating in the field of urban ecology of birds: i) Are cities ordinary components of the original environment with the same macroecological bird diversity patterns as can be observed in the surrounding environment or do they have some specific impacts on native avifaunas? ii) Which traits are characteristic for species being able to persist in cities and for those avoiding urban areas? iii) How does the impact of the most important factors influencing urban bird communities - area, habitat heterogeneity and spatial position - change with spatial scale? Towards answering these questions, data on breeding bird communities were extracted from 41 European urban bird atlases, avifaunas of regions in which cities are embedded were retrieved from the EBCC Atlas of European Breeding Birds. Finer scale bird community data were obtained from the atlas of Prague and by point counts conducted in Prague. Data on bird traits were collated from published resources and additional environmental and...
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The effects of forest clearings on bird populations
Eršil, Lukáš ; Policht, Richard (advisor) ; Ferenc, Michal (referee)
The most widespread way of extraction of forest is still clearlcuting. It is almost impossible to find commercial forest without forest clearings. Forest clearing can be perceived as a special element in a connected forest. I am trying to find out the influence of these forest distributions on the bird community. I was interested how important the forest clearings will be in the different type of forests. In seven localities were collected set of environmental variability's and bird data, which were counted by point count method. There were deciduous and mixed forests as well as the coniferous monocultures. The data collection was conducted in the breeding season 2011 and 2012. I expected, that the forest glades ensure the heterogeneity in forest space and will increase the number of bird's species. I expected this influence more important in the coniferous than in the deciduous and mixed forests. This assumption was partly confirmed. The glades in the coniferous forests have higher influence, but it depends on the forest area. In large coniferous monocultures is the importance of glades high. In the case of deciduous and mixed forests the size of forests did not have a value. The tree richness has the bigger importance. With this variable correlate Common Chiffchaff, Eurasian Wren, Yellowhammer,...
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Role of microorganisms in the evolution of reproductive strategies in birds
Novotná, Lucie ; Javůrková, Veronika (advisor) ; Ferenc, Michal (referee)
Microorganisms are ubiquitous and can be found on the body of birds, in avian nests or may be carried into the nest along with nest-lining material. Microorganisms may therefore colonize eggshells of eggs in a clutch and subsequently penetrate into the egg contents. This so called trans-shell infection has been observed to affect hatching success, cause embryo mortality or subsequently influence hatchlings phenotype. Nevertheless, the probability of eggshell bacterial load or trans-shell infection depends on many factors, including environmental conditions, nest type, incubation pattern, and nest-lining material. Furthermore, some modifications of avian reproductive strategies may lead to reduction of negative effect of trans-shell infections, and significantly improve reproductive success. These mechanisms include incubation, mechanical and chemical barriers of egg, eggshell pigments or using of feathers and specific plants as nest lining material. Based on these findings, it can be concluded that the different reproductive strategies in birds should be a result of strong selective pressure caused by microorganisms. Although many recent studies have supported this assumption, research on this issue still suffers from many methodological shortcomings that must be eliminated in future studies.
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