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The function and variability of song in two interacting nightingale species
Souriau, Abel ; Petrusková, Tereza (advisor) ; Kipper, Silke (referee) ; Linhart, Pavel (referee)
- ABSTRACT - The melodious and complex song of nightingales is a well-established model in studies focussing on the development and function of birdsong. Moreover, two sister species: the thrush nightingale (Luscinia luscinia) and the common nightingale (L. megarhynchos), meet in a recent secondary contact zone in Central Europe, in which their close ecological preference result in competitive interactions and interspecific hybridization. In sympatry, thrush nightingale males often replace part or all of their song repertoires with the songs of the common nightingale, a phenomenon called "mixed singing", while the opposite tendency has not been observed. Understanding the reasons behind the occurrence of thrush nightingale mixed singing, as well as exploring the similarities and difference in song structure between the two species, were the main aims of this thesis. In the first chapter, we tested the role of mixed singing on breeding common nightingale males and revealed its possible function in mediating territorial conflicts. Such advantage might be adaptive as it could help balance the potential costs of heterospecific song copying, and therefore help maintain the asymmetric song convergence between those species. The second chapter aims to explore further the function of thrush nightingale song...
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Effect of a dummy on passerine behaviour in playback experiments
Kubátová, Hana ; Petrusková, Tereza (advisor) ; Linhart, Pavel (referee)
Playback experiment is a frequently used method for the scientific research of the bird song and its functions. A recording of vocalization is played in the territory of the tested male, and its responses are observed. Majority of the studies using playback recordings presents only the acoustic stimulus. Sometimes a dummy is also used to provide a visual stimulus. This review focuses on the effects of the dummy on the passerine behavior in the playback experiments. In the first part a comparison is made within the groups of experiments with the same field of interest. The main questions are: how often is a dummy used in these types of experiments, how do designs and results differ depending on its presence/absence and, if possible, how do researchers evaluate its use. Subsequently, I tried to compare experiments with and without dummy within same species, but because of the differences of the experimental designs and the differences in forms of presentation the results, which were often not comparable, it was difficult to make clear conclusions. Next part analyses the few available studies where both trials with and without a dummy were performed on the same individuals. The review shows that the dummy allows tested males to express additional behavioural patterns, which can be noted by the...
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Individual variation in vocalization of Carnivores
Švůgrová, Barbora ; Linhart, Pavel (advisor) ; Vokurková, Jana (referee)
For carnivorans, as well as for other groups of animals, it is very important to be able to recognize other individuals. In this thesis, I focused on individual vocal variation in carnivoran's calls. I reviewed studies which desribed individual variability of calls in carnivorans. I focused on studies which used diskriminant analysis to quantify individual variation in calls. I updated the review of Insley et al. (2003) who suggested that the ability of individual recognition is more advanced in the Otariidae compared to Phocidae. My quantitative comparison on individual variability of Otariidae and Phocidae voices shows that the reason could be that Otariidae have more individually distinct voices. Furthermore, I compared the inidivuality in calls of other carnivorans. The comparison results do not support the hypothesis that animals living in groups have individually more variable voices than the animals living solitairy or in pairs. However, individuality seems to be influenced by ontogeny as it is easier to individually recognize calls of adults than calls of juveniles. In general, there have been many studies published about vocal individuality in carnivorans, but most of the research was done on just two very social families: Otariidae and Phocidae. It is necessary to study other carnivora...
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Boar vocalizations and their potential role in sexual selection
Roreitnerová, Daniela ; Linhart, Pavel (advisor) ; Schneiderová, Irena (referee)
The aim of this research was to gather existing knowledge about vocalizations of boars and their potential role in sexual selection. Few studies mainly from the 70s and 80s of the last century suggest that the so-called love song, emitted by males during courtship, could act as a stimulant that triggers mating. However, I did not find any evidence that boars significantly use calls in fights. Most studies deal with pig vocalization in a different context. For this reason, I tried to look at the studies of pig relatives - even-toed ungulates - to better evaluate the potential role of boar vocalizations in sexual selection. In their case, the influence of the calls on the sexual behavior of females and competing males was reported. It is possible to conclude that the role of boar vocalization is probably not that important as in red deers, for example, because boars use calls in short range communication. On the other hand, stimulatory effect on females was found in other species too. Further studies are needed to understand possible function of boar vocalizations that could be used for example in pig breeding to improve the effectiveness of artificial insemination of sows. Powered by TCPDF (www.tcpdf.org)
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Vocalization of the common cuckoo chicks: ontogenesis and influence of the host species and acoustic environment
Žabková, Klára ; Honza, Marcel (advisor) ; Linhart, Pavel (referee)
Brood parasitism is a breeding strategy which imposes significant selection pressure upon the host as well as the parasite. Consequently, specific adaptations were formed on both sides. One of the adaptations could be vocal behaviour of brood parasite juveniles. Several conducted studies suggested that juveniles of the common cuckoo (Cuculus canorus) adapt the form of their begging calls according to the host species they parasitize on. However, the outcomes of these studies were ambiguous. Therefore one of my tasks was to verify those findings. Two reed warblers - the great reed warbler (Acrocephalus arundinaceus) and the reed warbler (Acrocephalus scirpaceus) - living in sympatry were selected as the hosts. The structure of begging calls of common cuckoo juveniles raised by these two host species did not differ in any of the measured parameters (syllable duration, minimum and maximum frequency, peak frequency, frequency bandwidth and calling rate). On the contrary the structure of begging calls of own host juveniles varied significantly among the individual species. Moreover, a considerable individual variability was detected in both groups of cuckoo juveniles. Recent studies have revealed that juveniles already perceive sound and acquire knowledge of their parents' voices in the process of...
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Environment and avian song: case of South African birds
Mikula, Peter ; Albrecht, Tomáš (advisor) ; Linhart, Pavel (referee)
Relationship between animal signalization and environmental conditions, where these species are living, is one of crucial topics of ecology. Using two complementary statistical approaches (fourth-corner and RLQ analyzes) I investigated geographical variation in parameters of bird vocalization in South Africa (RSA) and Lesotho. Altogether, I used nine quantitative and five qualitative acoustic traits for 472 bird species and nine environmental variables which could significantly influence parameters of their vocalization. My results supported findings of previous studies about the important effect of body size on species-specific vocal characteristics. In passerines, analyzes corrected for body size showed that the number of elements and element types were increasing with variability of natural conditions and were highest in very arid and climatically unpredictable areas. Element and element type rate were positively associated with altitude. Minimal song frequency in passerines and frequency range of vocalization in other birds were negatively correlated with average temperature of warmest and coldest month of the year, respectively. Similarly, environmental variables significantly influenced distribution of several qualitative song traits in passerines. Passerines, where female song and...
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Individual acoustic monitoring of songbirds - case study on the tree pipit
Pišvejcová, Iveta ; Petrusková, Tereza (advisor) ; Linhart, Pavel (referee)
In field behavioural and ecological studies, it is often necessary to identify specific individuals. In birds, colour rings are often used as individual marks. However, rings might be difficult to observe, especially in small species and dense habitats. Thus recently, individual acoustic monitoring is becoming more commonly used to study of birds. This method is based on the recognition of individuals and often on the difference between temporal and spectral parameters of their vocalizations. However, in passerine species with more complex song these acoustic characteristics may not be reliable. In my thesis I used an alternative approach for the individual acoustic monitoring, based on differences in syllable repertoires of individual Tree Pipit males (Anthus trivialis). So far I have not found any study that would use a similar approach with other migratory passerine species with more complex song. The main aim of my study was to test the possibility of using syllable repertoires for recognition of specific individuals and to determine if this method is more efficient than identification by colour banding. From four years of research on the Tree Pipits population in the selected location in Brdy I received acoustic data from 59 males that I subsequently analyzed in a bioacoustic program. The...
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Role of evolutional mechanisms in designing of acoustic signals
Rulfová, Alena ; Policht, Richard (advisor) ; Linhart, Pavel (referee)
Acoustic communication is a wide-spread phenomen in all animal taxones. The theme of evolutional mechanisms and their functioning in acoustic communication has become more and more frequently studied during last years, and geographic variation in acoustic signals has been reported in various taxa such as insect, birds, anurans and mammals. However, some evolutional mechanism still remain poorly understood. The mechanisms comprise mainly stochastics forces such as genetic drift and bottleneck or cultural drift. Genetic drift causes stochastic changes in acoustic signals, whereas bottleneck probably primarily spawns reduction of acoustic variability. Some acoustic parameters are shaped by habitat and others by species' phylogeny. Physical environment and other ecological factors play important role in shaping vocalizations in most species, and thus distantly related populations occupying similar habitats may possess very simmilar vocalization. Because of that, revealing phylogenetic pattern is possible only by careful cladistic analysis of vocal characters in taxa that have simple songs or calls that are not learned, and whose habitat distributions are well understood. By finding the proper acoustic parameters we can also e.g. map connection between acoustic divergence and glaciations, history of colonisation...
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