Evidence of biphonation and source-filter interactions in the bugles of male North American wapiti (Cervus canadensis).
With an average male body mass of 320 kg, the wapiti, ITALIC! Cervus canadensis, is the largest extant species of Old World deer (Cervinae). Despite this large body size, male wapiti produce whistle-like sexual calls called bugles characterised by an extremely high fundamental frequency. Investigations of the biometry and physiology of the male wapiti's relatively large larynx have so far failed to account for the production of such a high fundamental frequency. Our examination of spectrograms of male bugles suggested that the complex harmonic structure is best explained by a dual-source model (biphonation), with one source oscillating at a mean of 145 Hz (F0) and the other oscillating independently at an average of 1426 Hz (G0). A combination of anatomical investigations and acoustical modelling indicated that the F0 of male bugles is consistent with the vocal fold dimensions reported in this species, whereas the secondary, much higher source at G0 is more consistent with an aerodynamic whistle produced as air flows rapidly through a narrow supraglottic constriction. We also report a possible interaction between the higher frequency G0 and vocal tract resonances, as G0 transiently locks onto individual formants as the vocal tract is extended. We speculate that male wapiti have evolved such a dual-source phonation to advertise body size at close range (with a relatively low-frequency F0 providing a dense spectrum to highlight size-related information contained in formants) while simultaneously advertising their presence over greater distances using the very high-amplitude G0 whistle component.
Mammal Vocal Communication and Cognition Research Group, School of Psychology, University of Sussex, Brighton BN1 9QH, UK reby@sussex.ac.uk.
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Reby
Mammal Vocal Communication and Cognition Research Group, School of Psychology, University of Sussex, Brighton BN1 9QH, UK.
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Wyman
Leibniz Institute for Zoo and Wildlife Research (IZW), Berlin 10315, Germany.
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Frey
Department of Science for Nature and Environmental Resources, University of Sassari, Sassari 07100, Italy.
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Passilongo
Laboratoire d'Acoustique de l'Université du Maine - UMR CNRS, le Mans 72085, France.
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Gilbert
Réserve de la Haute Touche, Muséum National d'Histoire Naturelle, Obterre 36290, France.
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Locatelli
School of Biology and Environmental Science, Science Centre West, University College Dublin (UCD), Belfield, Dublin 4, Ireland.
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Charlton
D000818:Animals; D003670:Deer / Q000502:physiology*; D005868:Gestures; D008297:Male; D009132:Muscles / Q000502:physiology; D009928:Organ Specificity; D010699:Phonation; D011187:Posture; D013018:Sound Spectrography; D014828:Vocalization, Animal / Q000502:physiology*
Deer; Elk; Formants; Mating call; Vocalisation; Whistling