National Repository of Grey Literature 63 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Geographical distribution of Piciforms' abundaces in Smrčina area, Šumava National Park
Souček, Michal ; Hořák, David (advisor) ; Riegert, Jan (referee)
The geographical distribution of Piciforms' is one of the factors indicating the state of the forest. These forest birds are bioindicators of climax forest communities. In Šumava National Park, some of the Piciforms' are flag species' and thanks to that, various historical data about them exist. The goal of my study was to evaluate data from 2006-2018 monitoring and add my own monitoring data from years 2019 and 2020. This data consists of location of individual birds living in the region called Smrčina, the southernmost point of the National Park. The goal of this thesis was to determine which factors influence the distribution. The method chosen for the monitoring was so called "point count method", used from the beginning of April till the end of June. For the statistical analysis, the R software was used. And for the visualization of geographical distribution, I used qGis. The result of my thesis is that from 10 Piciform species living in the Czech Republic, 8 live in the studied region. The abundance of Black Woodpecker and Great-Spotted Woodpecker from year 2006 and Three-Toed Woodpecker from year 2009 is stable. (Great- Spotted Woodpecker with 1,6, Black Woodpecker with 0,5 and Three-Toed Woodpecker with 0,8 pairs on one hectare.) The most rare species White-Backed Woodpecker was spotted...
Factors affecting farmland bird abundance in different European regions
Bystřický, Václav ; Reif, Jiří (advisor) ; Hořák, David (referee)
Farmland is a very important habitat for many open-habitat bird species. It serves as a food source as well as a breeding and wintering ground. In recent years, however, there has been evidence of population decline in some of these species. This decline is caused by various factors linked to human activities. The aim of this work is to summarise these negative factors and create a comprehensive overview of farmland bird populations status in different parts of Europe. I found that in comparison with other parts of Europe, a much more significant population decline of farmland birds occurs in western and northwestern Europe, mainly due to more intensively cultivated landscapes over the last decades. Central and Eastern European countries are less affected as they show lower intensity of land use associated with numerous small farms as well as the cultivation of spring cereals. In contrast, the abandonment of farmland may be one of the most threatening factors for the whole Mediterranean region. From the perspective of biodiversity conservation, one of the possible solutions could be a lower application of different types of pesticides, cultivation of various kinds of crops or longer- lasting stubble fields. Key words: farmland, birds, biodiversity, population decline, Europe
Effect of vegetation structure on abundance of lowland forest birds in Czechia and Slovakia
Tyčová, Barbora ; Hořák, David (advisor) ; Chmel, Kryštof (referee)
The vegetation provides an ecological space for birds and its structure reflects the availability of this place and resources. What specific influence does the vegetation structure have on bird abundance and which vegetation parameters are the most essential for bird species are classic, but still topical questions. The aim of this work was to find an answer using a study focused on birds in floodplain forests and to determine whether microhabitat characteristics affect the distribution of bird species within a single habitat. The data of this work were collected by the point counting method in six floodplain forests of the Czech Republic and Slovakia and statistically evaluated using regression, correlation and redundancy analysis. The birds were observed on a larger and smaller spatial scale. It was also used the study of the saturation of the environment by bird species over time and for the first time the analysis of habitat photo documentation as an alternative way for describing the vegetation structure. Results show that the analysis of vegetation photographs can be used to explain and predict avian abundance and thus create a new suitable method for birds' studies. Some bird species such as the collared flycatcher (Ficedula albicollis) and the Eurasian blue tit (Cyanistes caeruleus) have...
Influence of external conditions on egg incubation in lapwings (genus Vanellus) in temperate and subtropical climate
Pešková, Lucie ; Šálek, Miroslav (advisor) ; Hořák, David (referee)
During incubation, most birds require the presence of at least one parent to ensure suitable incubation conditions for embryo development. The main factors that affect the development of the embryo are temperature, humidity and egg turning. In this work, incubation conditions were investigated in two biparental Lapwing species (genus Vanellus), the Northern Lapwing (Vanellus vanellus), which faces the risk of egg cooling in temperate areas, and the Red-wattled Lapwing (Vanellus indicus), which faces the risk of egg overheating in the subtropics. A laboratory experiment testing the thermal properties of the Red-wattled Lapwing nest lining showed that it selects lining material that slows down temperature growth during egg heating, thus ensuring suitable thermal conditions during parental absence at high ambient temperatures. Temperature and egg turning during incubation were recorded by an artificial egg with a built-in sensors placed in the nests of both target species; data collected by the sensors were stored by a base-station located nearby. The average egg temperature was 32.5 řC for the Northern Lapwing, and 35.0 řC for the Red-wattled Lapwing. Egg temperature in both species fluctuated significantly, affected by many factors. Egg temperature increased with increasing ambient temperature, it...
Why are geographic ranges of species mostly small? Causes of range size variation
Kalendová, Pavlína ; Storch, David (advisor) ; Hořák, David (referee)
Species range size is collection of all regions which the specie occupies. Every specie has different range size, the most widespread are marine species. Range size distribution is log-normal, which means that the most of species have narrow ranges, some are widespread, and a few have extremely small ranges. This distribution can be a result of speciation and extinction. Speciation adds new species, which inhabits a part of original range. It causes a reduction of original range. Old species, which are getting closer to their extinction, are also declining their range together with abundance. One of the interesting theories is the stochastic theory, it is based on stochastic differential equation. This equation describes a changes of range size towards its equilibrium, which is the value when the range size is in steady state. The next factor is abundance. It is known that species with more individuals occupy larger ranges. Abundance distribution is also log-normal. In this thesis, I would try to summarize theories which explains why the most of species have small range sizes and how range vary among similar species.
Bird abundances and the height of vegetation
Černohorská, Eliška ; Hořák, David (advisor) ; Hanzelka, Jan (referee)
Bird abundance, it means the number of individuals at a specific site relates to the number of species in the area. It is common that species-richer habitats contain more individuals. Bird abundance which detected most frequently during the breeding period is influenced by the vertical structure of the vegetation so that habitats with low vegetation (e.g. grasslands) occupy smaller numbers of birds than the cover of higher vegetation (e.g. shrublands and forests). Most often total bird abundance positively correlates with increasing vegetation height determined by successional stages. Based at the stated studies, it is evident that bird species respond to vegetation height and its changes in a specific way, therefore it is difficult to make general conclusions. Negative correlation between vegetation height and bird abundance observed in some studies can be caused by various methods of data collection on vegetation height in different areas. In my opinion, bird abundance relates more to vegetation density and vegetation stratification than to vegetation height. The reason is that bird occurrence in forest habitats is impacted by well-developed undergrowth not just by forest canopy height. To further clarify how vegetation height affects bird abundance, we need more research that would compare bird...
Aesthetic value of biodiversity
Schmitzová, Daniela ; Hořák, David (advisor) ; Braun Kohlová, Markéta (referee)
The aesthetic experience of nature is a crucial part of human life. Because aesthetic experiences motivate people to engage in nature conservation, it makes sense to consider how biodiversity influences aesthetics and whether this influence can be used to promote conservation. First, this review touches on the measurement of nature's value to people and biodiversity, then discusses studies dealing with the connection of biodiversity and aesthetics. Nature offers a range of health benefits to people (e.g. stress relief, better recovery after surgery) that increase with biodiversity, but these benefits don't seem to increase the aesthetic value. At the landscape scale, heterogeneity of the environment is of particular importance, as is the presence of water bodies. For plant communities, biodiversity has a positive correlation with aesthetic value, and perceived biodiversity has a stronger effect in that regard. Preference is also influenced by the arrangement of planting. Aesthetically motivated nature conservation can potentially bolster biodiversity, as proven by the Lower Wisconsin State Riverway area, and should be considered a valuable conservation approach. Key words: biodiversity, aesthetics, species richness, functional diversity, value of the community/ecosystem, nature conservation
Ecological specializations of birds based on spatial co-existence patterns
Petrová, Kristýna ; Hořák, David (advisor) ; Weiser, Martin (referee)
Ecological specialization based on co-existence patterns is new methodology used for niche breadth measurement using co-existing community with occupancy data. It results in generalist-specialist continuum according to value of speciali- zation index. The aim of this thesis was testing index stability at spatial and tem- poral scale, compare this specialization index with other specialization indices and study changes in specialization with time changes in occupancy. Specialization was quantified using data of breeding birds atlases in the Czech Republic and Europe using two selected indices Theta and Simpson. Methodology seems to be sensitive to spatial scale. Instability appears at small scale for birds, stability and correlation between indices increase with gre- ater scale. Problems with using point counts corresponds to their unsuitability encompass birds' habitats, especially for water dependent birds. Correlations be- tween different time periods are stronger at greater spatial scale. Specialization based on co-existence patterns correlates with specialization according to experts' opinions. Results from comparing changes in specialization with changes in occu- pancy suggest, that most of species tend to leave more diverse sites with occupancy decline.
Ecological traits as a correlates of spatial variation in abundances of a Czech birds
Farkač, Jan ; Hořák, David (advisor) ; Reif, Jiří (referee)
Jan Farkač, Diplomová práce 2018 Abstract Bird species differ in their local densities, which seems to be related to their geographical distribution and species-specific traits. Investigating such a relationship can help us to understand better how the birds inhabit the space. The aims are as follow (i) to take an alternative approach to densities by counting them just in species preferred habitats and (ii) to explain the abundance characteristics such as an absolute density, variation in local densities or occupancy by species-specific traits. The relationship between abundance characteristics (local densities and their coefficient of variation in space) and avian traits such as a habitat specialisation, diet specialisation, PCA of morphological traits, PCA of reproduction traits - as an estimate of slow-fast continuum and a range size were tested using GLM. There are two abundance characteristics significantly related to species specialisation index. I have used the data from the Common Bird Monitoring Program run in the Czech Republic by the Czech Society of Ornithology. Due to the highest amount of records I have selected data from the year 2009 and subsequently species occupying more than 50 transects (out of 129), which resulted in inclusion of 47 species into analyses. This thesis contains...
Winter irruptions of birds in Europe
Souček, Michal ; Lučan, Radek (advisor) ; Hořák, David (referee)
Besides regular migrations, a phenomenon called "eruption", "invasion" or "irruption" exists in bird migratory behaviour. Although this phenomenon has been known since 19th century, its basic mechanisms are still not clear or are subjects of discussion. This bachelor thesis summarises in a form of review up-to-date knowledge and theories about winter irruption with information about all winter irruption occurrences in Czech Republic. Key words: Aves, irruption, winter invasion, migration

National Repository of Grey Literature : 63 records found   1 - 10nextend  jump to record:
See also: similar author names
1 Horák, D.
1 Horák, Dalibor
6 Horák, Daniel
4 Horák, David
1 Horák, Dominik
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