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Yellowhammer dialects and citizen science
Diblíková, Lucie ; Petrusková, Tereza (advisor) ; Linhart, Pavel (referee) ; Osiejuk, Tomasz S. (referee)
Bird dialects, the cultural phenomena that can be linked to migration, gene flow, speciation and cultural evolution, have been studied extensively. The yellowhammer Emberiza citrinella, a common European bird with a simple song and long singing season, has been a model species for studying dialects for decades. In this thesis, I collate several studies that benefited from citizen science approaches to push this field forward. First, we have compiled and unified information on yellowhammer dialect distribution scattered in numerous publications, and unified different dialect nomenclatures used in the past. We supplemented this with data available thanks to volunteers contributing to public databases and other online sources, and demonstrated that the continental distribution patterns of yellowhammer dialects do not support the existence of broad, geographically distinct macrodialect groups as previously believed. In 2011, as part of the Bird of the Year campaign of the Czech Society of Ornithology, we launched a year-long public awareness project "Dialects of Czech Yellowhammers". Its first year's results exceeded expectations in quality and quantity, so a one-year, conservation-focused citizen science project became a long-term, investigative one. In subsequent years, improvements to the web user...
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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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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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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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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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Vocal accommodation in howling of grey wolf (Canis lupus)
Schindlerová, Loretta ; Schneiderová, Irena (advisor) ; Linhart, Pavel (referee)
Vocal accommodation is the adjustment made by interlocutors while communicating, such as the adjustment of vocal pitch (i.e. the fundamental frequency) to match that of the other speaker. This behaviour can strengthen social bonds and has been predominantly studied in humans but recently also in the field of animal communication. Wolves are highly social animals and their howls - solos, duets, and choruses - are rich in information, yet vocal accommodation has not been studied in this species. Using a number of approaches, we explore whether grey wolves (Canis lupus) vocally accommodate to other wolves in duet howls by altering their howl contours to either converge to or diverge from another wolf's howl. To this aim we assessed the differences in the variables of the fundamental frequency and the contour of fundamental frequency using linear mixed models, Euclidean distance and dynamic time warping as metrics. Of the multiple analyses that we performed, one analysis identified significant differences between solo and duet howls, while another analysis indicated that duet howls within dyads were more similar than duet howls from different dyads. Our results point to the need for further exploration of the sources of variability and the role of context in order to confirm the existence of vocal...
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