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Condition dependence of sexually selected ornaments in birds
Tomášek, Oldřich ; Albrecht, Tomáš (advisor) ; Verhulst, Simon (referee) ; Šálek, Miroslav (referee)
Sexual ornaments important for mating success in many species are often assumed to evolve as condition-dependent signals of individual quality. Ornament expression can be associated with age and survival, thereby signalling individual viability. Here, we have tested viability signalling function of tail streamers and their importance for within-pair and extra-pair fertilisation success in the European barn swallow (Hirundo rustica rustica). In contrast to previous studies on this subspecies, our data suggest that tail length is not associated with fertilisation success in our population. Instead, the most important predictors of within-pair and extra-pair fertilisation success were female and male age, respectively. Our data supported viability signalling function of male tail streamers, as documented by age-related within- individual increase in their length. There was no evidence for senescence in this trait. Contrary to some previous studies, the viability signalling function of tail streamers was further supported by observed selective disappearance of males with shorter tails. Several physiological mechanisms have been proposed as maintaining signalling honesty. Among them, oxidative stress from highly reactive species (RS), including free radicals, attracted a considerable attention. Given...
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Signaling function of plumage coloration in Yellowhammer males
Kauzál, Ondřej ; Petrusková, Tereza (advisor) ; Šálek, Miroslav (referee)
Sexual selection theory tries to explain evolution of apparently useless traits which mainly developed in males of numerous species. One such trait is also rich and vibrant coloration, typical for many of the bird species. These traits are difficult to be falsified, and therefore they honestly signal quality of the individual. Carotenoid coloration reflects the health condition and melanin coloration the social status, even though this traditional division might not be as strict according to the latest studies. Apart from these ways of maintaining honesty, recent studies are focusing more also on the effect of hormones, mainly two steroids: male sexual hormone - testosterone -, and the "stress" hormone - corticosterone. Both hormones could positively influence male's sexual traits such as ornamental coloration. On the other hand, elevated levels of these hormones possess risk to the organism (higher energetic expenditure, chronic stress), therefore also might potentially become costly. Using photographs of birds in standardized conditions as well as spectrophotometry I analyzed the plumage coloration of males of the Yellowhammer (Emberiza citrinella). Concentrations of testosterone and corticosterone deposited in feathers were analyzed using the LC-MS/MS. Also, for males in breeding season 2015,...
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Influence of incubation temperature on avian embryo development
Pešková, Lucie ; Šálek, Miroslav (advisor) ; Hořák, David (referee)
Avian incubation is influenced by three basic factors: temperature, humidity, and egg rotation. The incubation temperature can significantly affect the development of an individual before hatching as well as after it. In natural conditions the incubation temperature is maintained by a parent trying to stabilize it at the developmental optimum. The parents must also provide their own needs during incubation, which results in temperature fluctuations. Although the incubation temperature is species-specific, its mean varies between 30 řC and 40 řC across all avian taxa. Lower temperatures but still within the optimum range cause reduced hatchability and prolongation of incubation period. Higher temperatures within the optimum range shorten incubation period and also reduce hatchability. Incubation temperature affects also the weight of an individual, its body proportions, metabolism, survival after hatching, and possibly also reproduction success (fitness). A detailed understanding of the mechanisms by which temperature affects the embryo development and its features is necessary, among others, to optimize incubation methods in artificial incubators. Key words: incubation, temperature, reintroduction, egg, avian embryo, hatchability, incubation length
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Factors influencing variability i behaviour towards novel and aposematic prey in tits (Paridae)
Adamová, Dana ; Exnerová, Alice (advisor) ; Sedláček, František (referee) ; Šálek, Miroslav (referee)
Inter-specific and intra-specific variation in reactions towards novel and aposematic prey was found in several species of tits (Paridae). This Ph.D. thesis is focusing on various factors influencing reactions towards novel and aposematic prey in three European species of tits. We tested differences in exploration behaviour, neophobia, dietary conservatism, personality, age and experience as well as ability of avoidance learning and generalisation. We found no difference in exploration behaviour and in reaction towards novel prey in two different populations of great tits (Parus major). But the birds from the Finnish population were more neophobic than Czech birds, but they attacked aposematic firebug (Pyrrhocoris apterus) more often and faster than Czech birds. The difference can be explained by a different experience with local aposematic prey communities. Than we studied initial wariness in naive juveniles of great tits (P. major), coal tits (Periparus ater) and blue tits (Cyanistes caeruleus), and we tested how the initial wariness towards novel and aposematic prey can be deactivated by experience with palatable prey. Great tits and coal tits from experienced groups significantly decreased their neophobia towards both types of prey while blue tits did not change their strongly neophobic...
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Bird communities in stands of non-native trees
Hanzelka, Jan ; Reif, Jiří (advisor) ; Hořák, David (referee) ; Šálek, Miroslav (referee)
6 Abstract This thesis deals with the effects of non-native tree stands on birds in the Czech Republic. Non-native plants, including trees, are known to adversely affect the biodiversity. At the same time, birds represent a widely used biodiversity indicator. The studies of bird communities in stands of non-native trees presented here show the extent to which the birds have been impacted by non-native tree stands. This knowledge can be used to evaluate the importance of non-native plants as a biodiversity threatening factor. As the representatives of widespread non-native trees, the broad-leaved black locust and coniferous black pine were selected. In these stands I investigated possible mechanisms affecting bird communities, arising from assumed differences in vegetation structure, bird species richness, bird community composition, food supplies, and nest predation pressure compared to the stands of native oak and native Scots pine. In general, the bird species richness positively correlates with the vegetation structure complexity. Despite the fact that the non-native stands proved to have a higher heterogeneity of vegetation structure than the native stands, bird species richness did not differ among the focal stands. The bird community composition was primarily affected by the birds' preference of...
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Epigamic behaviour in male Northern Lapwings: variability of visual attributes of song-flight and their relationships with other reproductive traits
Nacházelová, Martina ; Šálek, Miroslav (advisor) ; Exnerová, Alice (referee)
The Northern Lapwing (Vanellus vanellus) is a species with conspicuous courtship rituals, the most noticeable part being the males' aerobatic song-flight. The aim of this study was to determine which song-flight characteristics are important in female mate choice and whether the perceived difficulty of the song-flight is correlated with other indicators of male quality. In 2014 and 2015 male lapwings were observed in the meadows and arable land in South Bohemia, Czech Republic, in the vicinity of České Budějovice, a traditional breeding area. In 24 males we video-recorded their song-flights and observed mating behaviour and/or incubation of nests, had they any. We measured various aspects of the most dramatic displays of agility and stamina in the song-flight (Ascent, Vertical Dive, and Alternating Flight) in order to find which of them acted as influencing factors in female mate choice. We found that the more complicated the pirouette in the Vertical Dive and the faster the pace of the Alternating Flight, the earlier the male nested. The most convincing result showed that the longer the male spent more or less vertically inclined along his longitudinal axis in the Alternating Flight on one side before revolving to the other, the higher the probability for him to establish a polygynous bond - attract more...
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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...
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