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Pesticide impacts on farmland bird populations
Kutzendőrferová, Adéla ; Reif, Jiří (advisor) ; Grünwald, Jan (referee)
Pesticides are problematic chemicals that are found in a variety of environments. These substances tend to accumulate in living organisms, where they decomposite very slowly and can have a negative impact on bird populations. This is why some chemicals are still detected in these environments today, even years after their use has been banned, and may continue to affect organisms. The aim of my bachelor thesis was to conduct a literature search on the impact of pesticides on farmland bird populations. The first part of the thesis focuses on pesticides, their history, their division into different systems and their effects. The second part of the thesis then discusses the overall effects of pesticide use on farmland bird populations, particularly on breeding success and abundance. In this part, several studies have been collected that confirm the negative effect of pesticides on bird abundance, but not all of these studies are representative of real situations in the landscape. Finally, the paper assesses the overall role of pesticides in the observed bird declines and also presents suggestions to address the current negative trends. The thesis points to the need for expanded research studies that reflect actual conditions in agricultural landscapes to reveal the true extent of the effects of these...
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The Ecology of the Little Owl in European Farmland
CHRENKOVÁ, Monika
The little owl population in the most of Europe is rapidly declining mainly due to dramatic changes and transformation of the agricultural landscape, which resulted in the loss of suitable foraging habitats. Due to rapid population decline and range contraction, urgent conservation measures have to be implemented to save the population from extinction in certain areas. The thesis aims were to identify long-term population trend in selected regions, to uncover the habitat selection of breeding birds and to evaluate the effectiveness of individual management measures for the little owl conservation in the European farmland. The research on population status in Czech Republic and Slovakia revealed long-term population decline and marked distributional range contraction of the little owl, documenting its rapid local extinctions over the last two decades. On the contrary, results from Hortobagy National Park,representing the first large-area systematic survey in Hungary, indicate high population density and its widespread distribution. In particular, the study uncovers one of the highest population densities of this species from an agricultural landscape in Central Europe. Further detailed investigation of habitat selection at three different scales shows the link between certain habitat characteristics and species occurrence and supports the hypothesis of agriculture intensification being the main driver of the population decline of little owl in the Central Europe. Finally, the thesis provides evidence on the effect of different conservation management measures on little owl population in Denmark, where the species is close to extinction. Research findings indicate that food limitation during the breeding season may be the main reason for the declining numbers of little owls in Denmark. To prevent little owl extinction, evidence based conservation measures, such as provision of suitable foraging habitats with high availability and good accessibility of prey close to nests, are inevitable.
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Intraspecific variability in population trends of farmland birds: influence of habitat and altitude
Hanzelka, Jan ; Reif, Jiří (advisor) ; Šálek, Miroslav (referee)
Farmland bird populations in Europe have been in decline for a long time. Agricultural intensification and growing a large share of crops that provide suboptimal breeding habitat could be the main causes of the observed decline. To explore these possible drivers, I focused on population trends of farmland bird species in different habitats in the Czech Republic over the periods 1982-1990 and 1990-2010. Specifically, I focused on the variability in trends within each species in respect to the differences in landscape management between the lowlands and mid-altitude areas before and after 1990. The expected effect of intensive farming in the lowlands until 1990 was reflected by a strong decline in populations of Northern Lapwing and Yellowhammer. The influence of less intensive farming in mid-altitude areas causing moderate population decline was confirmed rather by shrubs and trees species than farmland specialists. After 1990, less intensive farming in the lowlands should reduce the decline, which may have occurred, but compelling comparison of population trends between the two time periods was not possible for most species due to the lack of data. On the contrary, more intensive population decline in mid-altitudes after 1990, which should be the response to arable land abandonment, was not...
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The importance of woodlots and their ecological characteristics for birds in an intensively managed agricultural landscape
Rajmonová, Lenka ; Reif, Jiří (advisor) ; Šálek, Martin (referee)
Various types of woody vegetation are a key biodiversity refugee in intensively managed agricultural landscapes. However, the role of woodlots, representing an important type of such a vegetation, remains overlooked so far. Whereas the previous studies focused on the effect of their area, shape and isolation, consequences of variation in their habitat quality for biodiversity were not assessed up to now. This thesis is thus one of the first studies focusing on woodlots as a specific habitat for birds in agricultural landscape. My goals were: (I) to find out what is the bird community composition of woodlots in a Czech landscape, (II) to find out, what are the key habitat predictors of bird species richness and abundance in woodlots, (III) to describe differences in habitat preferences among various guilds and (IV) to formulate recommendations for conservational practice. I surveyed birds in 82 woodlots in an intensively managed landscape in Central Bohemia, Czechia, and measured variables describing woodlots' habitat quality together with woodlots' area, shape, isolation and types of surrounding land-use. I recorded numerous forest and non-forest bird species (57 in total), including some endangered farmland birds. The habitat variables showing significant relationships to bird community...
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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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The importance of woodlots for birds in farmland
Rajmonová, Lenka ; Reif, Jiří (advisor) ; Zasadil, Petr (referee)
One of the outcomes of agricultural intensification is landscape homogenization, particularly obvious in developed countries. Unproductive plots of woody vegetation may represent a refuge for many species within large blocks of open areas. Eventhough it is crucial to assess the importance of such plots for animals in farmland, surprisingly, no synthesis on this topic has been published up to now. Therefore, performance of such an assessment is the main task of this bachelor thesis which is focused on birds since they heavily suffer from agricultural intensification. It was found that marginal vegetation provides not only habitat for breeding and foraging but also ecological corridor for birds᾽ short-distance movement and stopover sites for long-distance migrants. The structure of avian community is affected by specific characteristics of vegetation itself considerably and also by characteristics of landscape in smaller measure. Both farmland and forest birds occur in marginal vegetation, each of these bird groups utilizes these plots in a different way based on its ecological needs, however. The understanding of these mechanisms will allow effective conservation of biodiversity and restoration of once devastated areas. The main goal of conservation should be to ensure heterogeneous landscape mosaic...
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Intraspecific variability in population trends of farmland birds: influence of habitat and altitude
Hanzelka, Jan ; Reif, Jiří (advisor) ; Šálek, Miroslav (referee)
Farmland bird populations in Europe have been in decline for a long time. Agricultural intensification and growing a large share of crops that provide suboptimal breeding habitat could be the main causes of the observed decline. To explore these possible drivers, I focused on population trends of farmland bird species in different habitats in the Czech Republic over the periods 1982-1990 and 1990-2010. Specifically, I focused on the variability in trends within each species in respect to the differences in landscape management between the lowlands and mid-altitude areas before and after 1990. The expected effect of intensive farming in the lowlands until 1990 was reflected by a strong decline in populations of Northern Lapwing and Yellowhammer. The influence of less intensive farming in mid-altitude areas causing moderate population decline was confirmed rather by shrubs and trees species than farmland specialists. After 1990, less intensive farming in the lowlands should reduce the decline, which may have occurred, but compelling comparison of population trends between the two time periods was not possible for most species due to the lack of data. On the contrary, more intensive population decline in mid-altitudes after 1990, which should be the response to arable land abandonment, was not...
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