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Mechanisms enabling individual recognition of passerine birds
Caha, Ondřej ; Petrusková, Tereza (advisor) ; Vokurková, Jana (referee)
Vocalization allows birds to communicate over long distances or in environments, where can be difficult to detect visual signals. Vocalization can be divided into songs and calls. Song may inform a listener of signal about species, sex, male quality, aggressive motivation and also about singer's identity. Recognition of different individuals is very valuable ability that is commonly used during territorial interactions among males. Correct identification of males, that pose different threat, enable to respond adequately to the situation and save energy or to avoid injury in potential conflict. The ability of individual distinguishing based on song was demonstrated by using playback experiments for many passerines, but it was rarely revealed the way of such identification. This review deals with the issue of neighbour-stranger experiments that confirm the ability of passerines to discriminate between neighbours and strangers. Further, it focus on structures or characteristics of birdsong enabling individual recognition of passerines and their possibly use for individual acoustic monitoring.
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Individuální rozpoznávání na základě akustických signálů u pěvců
JAŠKA, Pavel
This study investigates the song-based recognition of individual songbirds with the main focus on the chiffchaff (Phylloscopus collybita) as a model species. The introductory part deals with vocalization-based recognition in birds in general.The following parts summarize our knowledge of individual recognition in songbirds based on song, namely the limitation of recognition ability caused by repertoire size or song sharing and how songbirds encode their identity in song. In the field study, we also proved the ability of the chiffchaff and willow warbler (Phylloscopus trochilus) to recognise particular neighbours based on one particular song from their repertoire. Our findings are interesting because chiffchaff and willow warbler differ in repertoire size and song organisation. We also analysed the repertoire size of chiffchaff males and the potential for identity encoding by basic voice characteristics (timing and frequency). We have found that chiffchaff song is unstable from year to year and that basic voice characteristics are useful for identification only when the same song type is used in the short time period. The last part of the thesis answers the question of whether there are some general voice characteristics independent of song content that might represent the structure of the sound organ and thus carry the identity of a bird independently of song content. We used ASRNI (Automatic system for the recognition of bird individuals) to identify particular birds based on unprocessed (raw) recordings of song without song preparation or manual measurements. This method also allows work with the data as an open set, so that the number of birds analysed does not have to be known in advance. Based on the parameters automatically extracted, we were able to recognise individuals with satisfactory accuracy. Based on such findings, we proved the existence of individually specific voice qualities that are independent of voice content and which may be used by birds for recognition. By using ASRNI we also introduced an approach that has great potential to be used in the effective acoustic monitoring of bird populations.
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Mechanisms enabling individual recognition of passerine birds
Caha, Ondřej ; Petrusková, Tereza (advisor) ; Vokurková, Jana (referee)
Vocalization allows birds to communicate over long distances or in environments, where can be difficult to detect visual signals. Vocalization can be divided into songs and calls. Song may inform a listener of signal about species, sex, male quality, aggressive motivation and also about singer's identity. Recognition of different individuals is very valuable ability that is commonly used during territorial interactions among males. Correct identification of males, that pose different threat, enable to respond adequately to the situation and save energy or to avoid injury in potential conflict. The ability of individual distinguishing based on song was demonstrated by using playback experiments for many passerines, but it was rarely revealed the way of such identification. This review deals with the issue of neighbour-stranger experiments that confirm the ability of passerines to discriminate between neighbours and strangers. Further, it focus on structures or characteristics of birdsong enabling individual recognition of passerines and their possibly use for individual acoustic monitoring.
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