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Context-related acoustic variation in male fallow deer (Dama dama) groans.

Charlton BD, Reby D - PLoS ONE (2011)

Bottom Line: We attribute this to the increased arousal state typically associated with this context.This indicates that, contrary to our predictions, male fallow deer do not exaggerate the acoustic impression of their body size by further lowering their formant frequencies in the presence of potential mating partners and competitors.Furthermore, since the magnitude of the variation in groan minimum formant frequency spacing remains small compared to documented inter-individual differences, our findings are consistent with the hypothesis that formants are reliable static cues to body size during intra- and inter-sexual advertisement that do not concurrently encode dynamic motivation-related information.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Biology, University of Vienna, Vienna, Austria.

ABSTRACT
While social and behavioural contexts are known to affect the acoustic structure of vocal signals in several mammal species, few studies have investigated context-related acoustic variation during inter-sexual advertisement and/or intra-sexual competition. Here we recorded male fallow deer groans during the breeding season and investigated how key acoustic parameters (fundamental frequency and formant frequencies) vary as a function of the social context in which they are produced. We found that in the presence of females, male fallow deer produced groans with higher mean fundamental frequency when vocal males were also present than they did when no vocal males were in close vicinity. We attribute this to the increased arousal state typically associated with this context. In addition, groan minimum formant frequency spacing was slightly, but significantly lower (indicating marginally more extended vocal tracts) when males were alone than when potential mates and/or competitors were nearby. This indicates that, contrary to our predictions, male fallow deer do not exaggerate the acoustic impression of their body size by further lowering their formant frequencies in the presence of potential mating partners and competitors. Furthermore, since the magnitude of the variation in groan minimum formant frequency spacing remains small compared to documented inter-individual differences, our findings are consistent with the hypothesis that formants are reliable static cues to body size during intra- and inter-sexual advertisement that do not concurrently encode dynamic motivation-related information.

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Spectrogram (A) and waveform (B) of a male fallow deer groan.Male fallow deer groans are low-pitched vocalisations characterised by a rapid downward shift in formant frequencies across the call (spectrogram settings: FFT method, window length = 0.05 s, time step = 0.01 s, Gaussian window shape, dynamic range = 30 dB).
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pone-0021066-g002: Spectrogram (A) and waveform (B) of a male fallow deer groan.Male fallow deer groans are low-pitched vocalisations characterised by a rapid downward shift in formant frequencies across the call (spectrogram settings: FFT method, window length = 0.05 s, time step = 0.01 s, Gaussian window shape, dynamic range = 30 dB).

Mentions: Groans were recorded from each of 18 male fallow deer at distances of 10–30 metres using a Marantz PMD 670 CF-card recorder and a Sennheiser MKH 416 P48 directional microphone (sampling rate of 44.1 kHz, 16 bits amplitude resolution). The sound files were transferred to an Apple Macintosh Macbook computer for visual inspection using narrow band spectrograms (see Figure 2: FFT method, window length = 0.03 s, time steps = 250, frequency steps = 1000, Gaussian window shape, dynamic range = 50 dB) and recordings with high levels of background noise were discarded. In total we used 269 groans from 11 males recorded on nine separate days. For each of the recording sessions we noted whether a vocally active male was within approximately 30 metres of the focal male. Vocal males are likely to constitute a greater threat because they are actively rutting [40]. We also noted whether any females were within 30 metres of the focal male (following [33]), and if the focal male was a harem holder.


Context-related acoustic variation in male fallow deer (Dama dama) groans.

Charlton BD, Reby D - PLoS ONE (2011)

Spectrogram (A) and waveform (B) of a male fallow deer groan.Male fallow deer groans are low-pitched vocalisations characterised by a rapid downward shift in formant frequencies across the call (spectrogram settings: FFT method, window length = 0.05 s, time step = 0.01 s, Gaussian window shape, dynamic range = 30 dB).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3113910&req=5

pone-0021066-g002: Spectrogram (A) and waveform (B) of a male fallow deer groan.Male fallow deer groans are low-pitched vocalisations characterised by a rapid downward shift in formant frequencies across the call (spectrogram settings: FFT method, window length = 0.05 s, time step = 0.01 s, Gaussian window shape, dynamic range = 30 dB).
Mentions: Groans were recorded from each of 18 male fallow deer at distances of 10–30 metres using a Marantz PMD 670 CF-card recorder and a Sennheiser MKH 416 P48 directional microphone (sampling rate of 44.1 kHz, 16 bits amplitude resolution). The sound files were transferred to an Apple Macintosh Macbook computer for visual inspection using narrow band spectrograms (see Figure 2: FFT method, window length = 0.03 s, time steps = 250, frequency steps = 1000, Gaussian window shape, dynamic range = 50 dB) and recordings with high levels of background noise were discarded. In total we used 269 groans from 11 males recorded on nine separate days. For each of the recording sessions we noted whether a vocally active male was within approximately 30 metres of the focal male. Vocal males are likely to constitute a greater threat because they are actively rutting [40]. We also noted whether any females were within 30 metres of the focal male (following [33]), and if the focal male was a harem holder.

Bottom Line: We attribute this to the increased arousal state typically associated with this context.This indicates that, contrary to our predictions, male fallow deer do not exaggerate the acoustic impression of their body size by further lowering their formant frequencies in the presence of potential mating partners and competitors.Furthermore, since the magnitude of the variation in groan minimum formant frequency spacing remains small compared to documented inter-individual differences, our findings are consistent with the hypothesis that formants are reliable static cues to body size during intra- and inter-sexual advertisement that do not concurrently encode dynamic motivation-related information.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Biology, University of Vienna, Vienna, Austria.

ABSTRACT
While social and behavioural contexts are known to affect the acoustic structure of vocal signals in several mammal species, few studies have investigated context-related acoustic variation during inter-sexual advertisement and/or intra-sexual competition. Here we recorded male fallow deer groans during the breeding season and investigated how key acoustic parameters (fundamental frequency and formant frequencies) vary as a function of the social context in which they are produced. We found that in the presence of females, male fallow deer produced groans with higher mean fundamental frequency when vocal males were also present than they did when no vocal males were in close vicinity. We attribute this to the increased arousal state typically associated with this context. In addition, groan minimum formant frequency spacing was slightly, but significantly lower (indicating marginally more extended vocal tracts) when males were alone than when potential mates and/or competitors were nearby. This indicates that, contrary to our predictions, male fallow deer do not exaggerate the acoustic impression of their body size by further lowering their formant frequencies in the presence of potential mating partners and competitors. Furthermore, since the magnitude of the variation in groan minimum formant frequency spacing remains small compared to documented inter-individual differences, our findings are consistent with the hypothesis that formants are reliable static cues to body size during intra- and inter-sexual advertisement that do not concurrently encode dynamic motivation-related information.

Show MeSH