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.
Highlights
Recent studies of mammal communication have highlighted the multi-component nature of vocal signals, and shown how the inter and intra-individual variation of the spectral components that compose these signals can simultaneously convey information on both static and dynamic attributes of callers
The results of this study indicate that the presence of mating partners and competitors has a significant effect on the vocal behaviour of male fallow deer, with frequency components of male groans varying between different social contexts
We have shown that the mean F0 of male fallow deer groans increases when males are with females and other vocal males are in close proximity
Summary
Recent studies of mammal communication have highlighted the multi-component nature of vocal signals (for review see [1]), and shown how the inter and intra-individual variation of the spectral components that compose these signals can simultaneously convey information on both static (long-term) and dynamic (short-term) attributes of callers. In the contexts of agonistic and sexual interactions, the ‘‘size’’ or ‘‘frequency’’ code hypothesis offers an evolutionary scenario whereby specific features of vocal signals known to encode honest information on static attributes of callers, such as their size, can simultaneously encode short-term, dynamic, motivational information [30]. This theory predicts that callers may evolve the ability to make ritualised use of relatively small variations of otherwise constrained parameters during social interactions. The possible ritualised use of acoustic cues to static attributes has not been investigated in the context of nonhuman mammal vocal interactions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
