|
|
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.
|
|
|
Being angry, singing fast? Signalling of aggressive motivation by syllable rate in a songbird with slow song
JAŠKA, Pavel
In this study, we focused on the role of syllable rate in territorial interaction of chiffchaff males. We confronted each tested male with one of three playback types which differed in song rate (slow, non-manipulated, fast). The behaviour and the song of each subject were recorded before, during and after the treatment. Males that attacked the loudspeaker during playback sang faster before the stimulation. When birds continued singing during playback they increased syllable rate when exposed to fast or non-manipulated song. Our results indicate that syllable rate could be a signal of aggression in chiffchaff and play a role as a conventional signal rather than a handicap signal.
|
|
|
Song as a signal of competitive ability and motivation in Chiffchaff
JAŠKA, Pavel
The basic aim of the thesis was testing the role of song length and syllable rate in male {--} male interactions in chiffchaff (Phylloscopus collybita). I looked for correlations between morphological measurements and vocal characteristics. I also presented stimuli manipulated in length and syllable rate to the chiffchaff males in the field playback experiments.
|
|
| |
guest ::
RSS feed.