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Hatching synchrony in birds
Tippeltová, Zuzana ; Hořák, David (advisor) ; Riegert, Jan (referee)
This bachelor thesis is about hatching synchrony in birds. Generally, among birds there are two types of hatching - asynchronous and synchronous- and the type of hatching is primarily determined by the time of the onset of incubation. In many bird species, including most precocial ones, incubation does not begin until the last egg has been laid, which results in hatching of all the eggs within a few hours. In synchronously-hatched broods, all the chicks are about the same age. Thus no single individual has an advantage in size or strength over any of its siblings in the nest. The survival probability is then similar for all chicks which maximizes number of fledglings under favourable condition. In contrast many species of birds begin to incubate as soon as the first eggs is laid and hatch their eggs asynchronously over a period of days or weeks, handicapping last-hatched chicks with an age and size disadvantage. Many hypotheses have been proposed to explain why female birds start to incubate before clutch completion and some of those suggest that asynchronous hatching is a parental strategy for raising the largest number of offspring that food resources will allow when the abundance of food for the chicks cannot be predicted at the time that eggs are laid. The selective pressures leading to the evolution of...
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Testing of functions of song types and specific structures of tree pipit song
Kinštová, Anna ; Petrusková, Tereza (advisor) ; Riegert, Jan (referee)
4 Abstract Bird song is usually considered to have two primary functions; attract females and repels males. Hence, song features can be an indicator of male quality or aggressive motivation. It has been suggested that one of those features could be in the form of a trill - physically demanding structures. Two types of trill has been found in tree pipit, Anthus trivialis, "I" and "M" trills. Trill rates significantly differ among males in this species therefore we assume that repetitive syllable production may indicate male quality. Firstly, we tested if both types of trills are used in aggressive context using playback experiments. Only "I" trills were sung by males in response to playback, regardless of the type of trill involved in playback. Moreover, males increased the frequency of the singing of that trill as an immediate response to playback, and also increased the trill rate in comparison with spontaneous songs. In addition males who sung faster "I" trills were able to maintain the territory. We conclude "I" trills may carry information about the signaller's aggressiveness. Surprisingly, production of "M" trills decreased after the simulated territorial intrusion. Secondly, we tested hypotheses that males modify their response according to the intruders' quality therefore we used playbacks containing...
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Reproductive senescence in female barn swallows (Hirundo rustica): age-related changes in components of reproductive success
Pazdera, Lukáš ; Tomášek, Oldřich (advisor) ; Riegert, Jan (referee)
The effect of age on an individual's fitness is one of the key topics of evolution ecology. Currently intensively studied manifestation of age is an aging of organism, thus a deterioration of metabolic functions and condition with age. An increasing count of studies shows that aging in the wild is rather a rule than exception, even with short-lived species of which the aging has not been previously presumed at all. Despite an increasing interest of evolution ecologists in this matter, some important aspects remain overlooked. Senescence of the traits are usually studied separately, therefore, an information whether an individual traits show similar or different aging dynamics is missing. The information is needed to assess if the signs are aging synchronously, as predicted by the William's antagonistic pleiotropy theory, or rather asynchronously. The suitable traits for study are these, which are involved in a reproduction activity. The reproduction is a sequential process consisting of many components, e.g. an expression of sexual ornaments (attractivity), nesting timing, amount of eggs laid and their size, etc. There is currently a little knowledge of which of these reproduction components are affected by the aging the most, and which are resistant to the the effect of age. Well studied is...
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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...
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Reproductive senescence in female barn swallows (Hirundo rustica): age-related changes in components of reproductive success
Pazdera, Lukáš ; Tomášek, Oldřich (advisor) ; Riegert, Jan (referee)
The effect of age on an individual's fitness is one of the key topics of evolution ecology. Currently intensively studied manifestation of age is an aging of organism, thus a deterioration of metabolic functions and condition with age. An increasing count of studies shows that aging in the wild is rather a rule than exception, even with short-lived species of which the aging has not been previously presumed at all. Despite an increasing interest of evolution ecologists in this matter, some important aspects remain overlooked. Senescence of the traits are usually studied separately, therefore, an information whether an individual traits show similar or different aging dynamics is missing. The information is needed to assess if the signs are aging synchronously, as predicted by the William's antagonistic pleiotropy theory, or rather asynchronously. The suitable traits for study are these, which are involved in a reproduction activity. The reproduction is a sequential process consisting of many components, e.g. an expression of sexual ornaments (attractivity), nesting timing, amount of eggs laid and their size, etc. There is currently a little knowledge of which of these reproduction components are affected by the aging the most, and which are resistant to the the effect of age. Well studied is...
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Habitat specialization as determinant of species response to the Global Change
Rivas Salvador, Javier ; Reif, Jiří (advisor) ; Riegert, Jan (referee) ; Skorka, Piotr (referee)
Human-induced global change is altering the environmental systems as we know them. Significant evidence has been acquired that suggests these changes are triggering the sixth mass extinction. This biodiversity loss seems to not be occurring at random, but it is targeting species differently according to their niche breadth. Species with a narrow habitat niche seem to be experiencing strong population decline, especially due to the intense natural habitat transformation. Therefore, we investigated the role of habitat specialization within species ecology and its conservation implications, obtaining the following key findings: Habitat specialists gathered in montane regions and in areas with harsh climate conditions (cold and highly seasonal) across the European continent. Furthermore, we found two specialization hotspots, one in northern Scandinavia and one in the steppe region north of Caucasus. Additionally, we found that specialists and habitat generalists merge in the same communities. Habitat specialization predicts population declines at European pancontinental scales. It brings further support for widespread process biotic homogenization, likely caused by current human-induced land use and climate changes. When we tested whether conservation benefits of mid-field woodlots were...
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Breeding and singing activity of rainforest birds along an elevational gradient in tropical Africa
Zenklová, Tereza ; Sedláček, Ondřej (advisor) ; Riegert, Jan (referee)
Tropical areas are usually expected to be a stable environment when compared to the temperate zone. This is true especially for the temperature and the day length which ensure relatively stable food supply. As a consequence, tropical birds, especially rainforest species, are thought to breed all year round. But even in the tropics, breeding can be synchronized with some fluctuating environmental conditions such as rainfall and differences in food supply and breeding and singing activity may occur seasonally in tropical rainforest as well. But the data for testing these assumptions are still scarce. In the first part of my thesis, I focused on the seasonality in breeding activity in various feeding guilds of birds inhabiting tropical rainforest on Mount Cameroon in three different elevations - lowland, submontane and montane forest. The second part focuses on the seasonality in singing activity at both population and species level. I also compared singing activity with the data on breeding activity. The extent of breeding activity differed between feeding guilds and I showed preferences of different guilds to different seasons for breeding. Most of the groups, especially insectivorous birds, bred in the beginning of the dry season, except of species searching for invertebrates on the ground. These...
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Testing of functions of song types and specific structures of tree pipit song
Kinštová, Anna ; Petrusková, Tereza (advisor) ; Riegert, Jan (referee)
4 Abstract Bird song is usually considered to have two primary functions; attract females and repels males. Hence, song features can be an indicator of male quality or aggressive motivation. It has been suggested that one of those features could be in the form of a trill - physically demanding structures. Two types of trill has been found in tree pipit, Anthus trivialis, "I" and "M" trills. Trill rates significantly differ among males in this species therefore we assume that repetitive syllable production may indicate male quality. Firstly, we tested if both types of trills are used in aggressive context using playback experiments. Only "I" trills were sung by males in response to playback, regardless of the type of trill involved in playback. Moreover, males increased the frequency of the singing of that trill as an immediate response to playback, and also increased the trill rate in comparison with spontaneous songs. In addition males who sung faster "I" trills were able to maintain the territory. We conclude "I" trills may carry information about the signaller's aggressiveness. Surprisingly, production of "M" trills decreased after the simulated territorial intrusion. Secondly, we tested hypotheses that males modify their response according to the intruders' quality therefore we used playbacks containing...
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Hatching synchrony in birds
Tippeltová, Zuzana ; Hořák, David (advisor) ; Riegert, Jan (referee)
This bachelor thesis is about hatching synchrony in birds. Generally, among birds there are two types of hatching - asynchronous and synchronous- and the type of hatching is primarily determined by the time of the onset of incubation. In many bird species, including most precocial ones, incubation does not begin until the last egg has been laid, which results in hatching of all the eggs within a few hours. In synchronously-hatched broods, all the chicks are about the same age. Thus no single individual has an advantage in size or strength over any of its siblings in the nest. The survival probability is then similar for all chicks which maximizes number of fledglings under favourable condition. In contrast many species of birds begin to incubate as soon as the first eggs is laid and hatch their eggs asynchronously over a period of days or weeks, handicapping last-hatched chicks with an age and size disadvantage. Many hypotheses have been proposed to explain why female birds start to incubate before clutch completion and some of those suggest that asynchronous hatching is a parental strategy for raising the largest number of offspring that food resources will allow when the abundance of food for the chicks cannot be predicted at the time that eggs are laid. The selective pressures leading to the evolution of...
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