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Selected impacts of climate change on birds in European mountains: shifts in altitudinal distribution, population changes and changes in phenology
Mikulcová, Eliška ; Reif, Jiří (advisor) ; Hološková, Adriana (referee)
Many studies focused on the impact of the climate change on organisms including mountain birds. Mountain birds are particularly threatened by the impact of climatic change because they occur in an extreme environment. Climate change impacts mountain birds through increasing temperature, which affects their altitudinal shifts and abundances. These two variables depend also on species-specific traits, distribution area and habitat change. This thesis aims to sort knowledge about impacts of climate change on mountain birds and to explain the variability of altitudinal shifts of these species. Species occupying lower altitudes, open habitat species and short-lived species showed the biggest upward shifts. Downward shifts occurred when the impact of habitat change outweighed the impact of climate change. No significant shifts were recorded in species that respond to climate change by changes in phenology which likely compensate the adverse climate change impacts without the need of translocation. Population trends were usually negative with the steepest declines in high- alpine species, ecological specialists, long-distance migrants and short-lived species. In order to reduce decline in numbers, it is important to set up effective local vegetation management and globally stick to climate targets. Key...
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Influence of food supply and habitat characteristics on the abundance of birds in intensively managed arable fields
Hološková, Adriana ; Reif, Jiří (advisor) ; Krištín, Anton (referee)
The decline of farmland birds is a well-documented phenomenon attributed to the impacts of agricultural intensification. However, the specific mechanisms responsible for population declines in individual species have not yet been satisfactorily elucidated. Most research has focused either on the influence of habitat characteristics or on the food supply. The aim of my thesis was therefore to link these two factors. The study was carried out in an intensively managed farmland of southwestern Slovakia. In the fields of winter wheat, winter rape and maize, I recorded the abundance of birds, namely Yellow Wagtail (Motacilla flava) and Eurasian Skylark (Alauda arvensis), habitat characteristics and food supply. Yellow Wagtail avoided maize fields, but its abundance did not differ among the other crops significantly. However, the number of wagtails varied within fields, as they more often occurred closer to field edges, most likely due more abundant and diverse food supply found near the edges. A positive relationship between the number of wagtails and invertebrate diversity further supports this explanation. Skylark abundance did not vary across the focal crops, but it was negatively affected by the presence of woody plants at the field edge. Neither the abundance nor the diversity of the food supply...
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Towards the understanding of agricultural intensification impacts on farmland birds: the effects of changes in invertebrate food supply
Hološková, Adriana ; Reif, Jiří (advisor) ; Lučan, Radek (referee)
Populations of insectivorous farmland birds recently underwent dramatic declines. Agricultural intensification is the main cause of these population changes, but involves numerous different mechanisms. Changes in food supply are thought to be one of the key factors. Homogenization of diet supplied to insectivorous chicks reduces their growth rate resulting in their smaller size as adults; decreased abundance of prey affects both survival and fitness of chicks and the overall breeding success. The accessibility of food is one of the most important factors limiting the use of food-rich habitats. However, the impact of all these factors on population trends has been shown in a single species - grey partridge. While the effect of changes in food supply on the breeding success has been confirmed in many other species, there is a lack of information on subsequent links to the survival of fledglings and the major causes of mortality outside the breeding period remain unclear. In general, there is insufficient information on population consequences of the changes in food supply for farmland birds, particularly in Central and Eastern Europe - the region with different characteristics from those we find in regions in which most of the findings were collected. Without this information, it is difficult to...
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