Infrasound in mating displays: a peacock's tale

Male peafowl display to females with erection and movement of their elaborately ornamented train. We hypothesized that the male's concave train serves as a radiator of acoustic signals, and thus examined both the production and perception of acoustic signals associated with these displays in Indian peafowl, Pavo cristatus. We discovered that male train displays produced infrasonic signals, which were perceived by both male and female peafowl. Both males and females responded to a subset of infrasonic signals by increasing the time they spent walking/running and being alert during playbacks relative to baseline controls. Male peafowl also increased rates of vocalization in response to infrasonic signals, but not to audible train-based signals. The apparent intra- and intersexual saliency of these signals suggests that they play a potent role in peafowl social signalling. Infrasonic signals are likely adaptive in the peacock's natural habitat, as they would attenuate minimally as they are propagated through dense vegetation that otherwise would attenuate high frequencies in audible signals and obstruct visual signals.