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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...
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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.
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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...
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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
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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.
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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...
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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
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Haemoproteus in passerines: infection dynamics at the individual level
Chalupová, Barbora ; Svobodová, Milena (advisor) ; Hořák, David (referee)
The genus Haemoproteus is worldwide distributed parasitic protist, which belongs to the phylum Apicomplexa. This blood parasite has dixenous life cycle and he is occurs in the bird's blood and in invertebrate vectors. Genus Haemoproteus is transmitted by blood-sucking vectors, biting midges (Ceratopogonidae) and hippoboscid flies (Hippoboscidae). Vectors are final hosts of the genus Haemoproteus and the sexual process takes place in these vectors. Birds are intermediate hosts, in which representatives of the genus Haemoproteus spend most of their lives. In this bachelor thesis I focused on the influence of the genus Haemoproteus on birds and I focus on the time, when the bird gets infected by Haemoproteus in his life. Key words: Haemoproteus, birds, infection, life cycle, host, Ceratopogonidae, Hippoboscidae
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Migratory divide in European birds
Branišová, Dominika ; Hořák, David (advisor) ; Klvaňa, Petr (referee)
This bachelor thesis deals with migatory divide in European birds, i.e. the contact zone between two population of one species differing in migration path and wintering site. It also comments on related methodological approaches, such as ringing, emlen funnels, satellite tracking or stable isotopes analysis. Between species with best documented migratory divide belong for example blackcap (Sylvia atricapilla) or willow warbler (Phylloscopus trochilus). In birds, many mechanisms are responsible for the creation of the migratory divide: (i) the colonization of Europe after the last glaciation by two or more populations of one species living in refugias, (ii) the presence of natural barrier separating populations and affecting their migration patterns, (iii) the impact of climate change as it causes selection pressure on a certain part of the population and creates differences in migratory behavior. Among key factors responsible for maintaining the divide belong mechanisms ensuring the low gene flow between populations, such as: (i) selection against hybrids or assortative matting. In non-passerines, also other mechanisms have been reported, such as learning migration route in juveniles from adults. Existence of migratory divides is supported by the selection pressure to find an optimal migration strategy,...
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