|
|
Species-area relationship in birds: variation across temperate zone environments
Gaigr, Matěj ; Hořák, David (advisor) ; Hanzelka, Jan (referee)
The relationship between area and number of species is one of the oldest and most studied principles in ecology, often referred to as one of the laws of ecology. Ecologists use it primarily to model the expected number of species in a given area. The Species-Area Relationship (SAR) states that the larger the area being, the greater the number of species present. However, area is not the only factor influencing species diversity - habitat heterogeneity is also a frequently studied factor affecting species richness. The number of species in an area tends to be positively influenced by heterogeneity since factors that are positively correlated with heterogeneity have a large influence. These factors include the species diversity of vegetation, the level of energy productivity, the number of microhabitats, the effect of disturbance or the amount of different food sources. Individual temperate habitats differ in the relative contribution of heterogeneity in its impact on observed species abundance. Species abundance is not only influenced by habitat heterogeneity, but also by other factors such as altitude, climate or latitude. The most affected habitats regarding the relative contribution of heterogenity are forest environments. Vertical diversity is the main influence causing high heterogeneity in...
|
|
|
Temporal changes in bird communities at the landscape level in Třeboň basin
Havelka, Jan ; Sedláček, Ondřej (advisor) ; Reif, Jiří (referee)
Population trends of birds are usually studied mainly on large national and continental scales or, on the contrary, quite locally. In an attempt to link these spatial scales, we repeated a quantitative survey of bird communities in the Třeboň Protected Area twenty years later (between 2001 and 2021). Bird counts were conducted during the breeding season on a fifty- kilometre transect (128 count points) intersecting a diverse range of habitats. We found declines in long-distance migrants and insectivorous birds compared to more stable or slightly increasing populations of resident species. Consistent with known trends, we also observed declines in populations of species tied to agricultural landscapes. Deviations from the well described trends by JPSP and PECBMS relate more to individual species characteristics. For example, we observed increases in populations of otherwise declining House Sparrow (Passer domesticus) and Field Sparrow (Passer montanus), or nationally stable Eurasian Siskin (Spinus spinus). Using detailed mapping of habitat and vegetation changes and other ecological characteristics of individual species, we have attempted to explain these general and site-specific changes in bird abundance and population trends. We were also interested in the manifestations of the generally...
|
|
|
Drivers of avian diversity on an altitudinal gradient of Mount Cameroon
Djomo Nana, Eric ; Hořák, David (advisor) ; Šálek, Miroslav (referee) ; Waltert, Matthias (referee)
Altitudinal gradients constitute a powerful test system for understanding distribution of species around the globe. Tropical mountains are quite rich in species even after controlling for environmental productivity, and are ideally suited for studying patterns of species distributions because they have had sufficient time for species to produce a response to environmental changes that affect their life histories. In this thesis, I investigate basic ecological mechanisms potentially behind avian distribution patterns along an altitudinal gradient in West-Central Africa. I used data collected with four methodological approaches (point counts, mist netting, random walks and artificial nest experiments) along an altitudinal gradient on Mt. Cameroon from October 2011 to September 2013. This work is focused on two interrelated themes: selection pressures on life histories (Chapters 1, 2, 3 & 4), and avian assemblage structures (Chapters 5 & 6). In the General Introduction, I present an overview of the study area with conservation implications of the study and my study objectives. In Chapters 1, 2 & 3, I investigate how selection pressures, i.e., nest predation and parasitism by haematozoa, affect bird assemblages. I used artificial nest experiments to assess nest predation rates in Chapters 1 & 2, and my...
|
|
|
Influence of temperate zone wetlands drying and overgrowth on bird diversity and abundance
Tuháček, Filip ; Hořák, David (advisor) ; Cepák, Jaroslav (referee)
Wetlands, the essential ecosystems, contain plenty of animal and plant species. Due to their various types and characters, wetlands support very different organisms, especially birds. Animals are thanks to their adaptation made for life in water, and some species are water-dependent - they use wetlands to forage and as breeding sites or nesting sites. Birds, and mainly waterbirds, require var- ious habitat characteristics because some of these habitats are due to bird diverse ecology suitable just for a few bird species. Wetlands drying and overgrown is a major threat for these ecosystems, and they are influencing birds in different ways. The efficiency of hunt or food availability may be affected by both changes in water depth and the density and extent of vegetation. These variables have a diverse effect on nesting birds, firstly on habitat selection for nesting and secondly on nesting success and survival mainly because of predators, because predation tends to be increasing with decreasing both water depth and nest cover. In terms of possible wetland management and restora- tion, we have to remember that we cannot generalize these effects for all bird species. Possibilities are creating new wetlands or restoration, such as vegetation cutting, burning, and livestock grazing. These options bring...
|
|
|
Bird Communities Along the Altitudinal Gradient on Mt. Cameroon: Perspectives from Mist Nets
Petruf, Miroslav ; Sedláček, Ondřej (advisor) ; Lučan, Radek (referee)
in English Mt. Cameroon is a hotspot of diversity and endemism in Africa. Recent research of avian bird communities along the elevational gradient on Mt. Cameroon based on point counts has shown low-elevation plateau of species richness. At the same time, range-restricted montane populations of birds on Mt. Cameroon are unusually abundant if compared to lowland species. I analysed data on community composition, species richness and abundance of birds using an alternative quantitative method - 200 m of understory mist nets erected for three consecutive days across seven elevational plots along the forested gradient of the Mt. Cameroon. First, I looked at the technical limits of this method and confirmed the general opinion that they are better at detecting small birds below 33 g, and that they mostly detected fewer individuals after the first day and always detected fewer new species after the first day of mist-netting. Mist nets detected high proportions of ground-feeding and understory birds and low proportions of birds foraging in higher strata in the lowland forest, which has a scarce understory and a dense canopy. Mist nets recorded similar proportions of birds foraging in all forest strata in the vastly open mid-elevation forest, which has a dense herbaceous understory. They detected higher...
|
|
|
Funkční diverzita ptačích společenstev na ostrovech Oceánie
KOTOUNOVÁ, Adéla
Functional diversity is important part of biodiversity. It describes how organisms influent enviroment and how organisms respond to changes in the enviroment. First, I reviewed current knowledge, because the research of functional diversity accumulates exponentially, and new indexes appear quickly. The functional diversity is mostly calculated for plant communities, for which we have majority of available information those is nowadays the most available information. To fill knowledge gaps, I aimed to describe the functional diversity of bird communities on the islands of Oceania.
|
|
|
Drivers of avian diversity on an altitudinal gradient of Mount Cameroon
Djomo Nana, Eric ; Hořák, David (advisor) ; Šálek, Miroslav (referee) ; Waltert, Matthias (referee)
Altitudinal gradients constitute a powerful test system for understanding distribution of species around the globe. Tropical mountains are quite rich in species even after controlling for environmental productivity, and are ideally suited for studying patterns of species distributions because they have had sufficient time for species to produce a response to environmental changes that affect their life histories. In this thesis, I investigate basic ecological mechanisms potentially behind avian distribution patterns along an altitudinal gradient in West-Central Africa. I used data collected with four methodological approaches (point counts, mist netting, random walks and artificial nest experiments) along an altitudinal gradient on Mt. Cameroon from October 2011 to September 2013. This work is focused on two interrelated themes: selection pressures on life histories (Chapters 1, 2, 3 & 4), and avian assemblage structures (Chapters 5 & 6). In the General Introduction, I present an overview of the study area with conservation implications of the study and my study objectives. In Chapters 1, 2 & 3, I investigate how selection pressures, i.e., nest predation and parasitism by haematozoa, affect bird assemblages. I used artificial nest experiments to assess nest predation rates in Chapters 1 & 2, and my...
|
|
|
THE EFFECT OF AN INCREASING COVERAGE OF INVASIVE BLACK LOCUST ON BIRD COMMUNITIES IN FOREST STANDS
Kroftová, Magdalena ; Reif, Jiří (advisor) ; Ferenc, Michal (referee)
Biological invasions are one of the most important threats to global biodiversity and they were also found to negatively affect some bird species. Despite relatively large number of scientific studies dealing with the impacts of invasive plants on bird communities, their results are inconsistent, especially it is not clear how birds respond to increasing levels of expansion of invasive species in native species stands. Moreover, bird responses to plant invasions seem to depend on the ecological characteristics of individual bird species. This study contributes to elucidation of this problem; I investigated the impacts of black locust (Robinia pseudoacacia) invasion on bird communities in three types of forest stands with different levels of invasion: in stands containing solely the native oak (Quercus spp.), in partially invaded stands with different proportions of black locust and oak (mixed stands) and in pure black locust stands. Previous studies that examined birds in pure oak and pure black locust stands have found that they differ markedly in vegetation structure, but not in the total number of bird species. However, habitat specialists were associated with the oak stands, while generalists with the black locust stands. Therefore, I predicted that (1) the total species richness will be...
|
|
|
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,...
|
|
|
Bird communities in the invasive Knotweed (Reynoutria sp. div.)
Hajzlerová, Lenka ; Reif, Jiří (advisor) ; Sedláček, Ondřej (referee)
Although it is widely recognized that exotic plant invaders can affect diversity of native plant communities, a few studies of natural systems concern about the nature abundance and diversity loss and the associated consequences for higher trophic levels. Little is known impact of exotic riparian plant on higher-order consumers, such as birds. Such is requirement to understand underlying mechanisms of invasive processes and formulating effective management strategies. We examined interaction between invasive knotweed (Reynoutria sp. div., next only knotweed) and bird communities. We recorded occurrence of birds along three rivers in riverbanks that were either dominated by native vegetation or invaded by knotweed. Birds were recorded in breeding seasons in 2011 and 2012 near town Frýdek-Místek and Valašské Meziříčí. We interested especially in (i) how knotweed composition within riparian systems affects avian communities and (ii) what common bird characteristics are influenced by knotweed. Our outcome found positive effect of Marsh Warbler (Acrocephalus palustris) and Great Tit (Parus major) in high knotweed cover and negative effect of Grey Wagtail (Motacilla cinerea). Interspecific comparison common avian characteristics suggest that knotweed invasion can impact avian abundance living in lower...
|
guest ::
