ABSTRACT
Feathers act as vibrotactile sensors that can detect mechanical stimuli during avian flight and tactile navigation, suggesting that they may also function to detect signals during social displays. We explored this novel sensory modality using the crest plumage of Indian peafowl (Pavo cristatus). We first determined whether the airborne stimuli generated by peafowl courtship and social displays couple efficiently via resonance to the vibrational response of feather crests from the heads of peafowl. Peafowl crests were found to have fundamental resonant modes with frequencies that could be driven near-optimally by the shaking frequencies used by peafowl performing train vibrating displays. Crests also were driven to vibrate near resonance when audio recordings of sounds generated by these displays were played back in the acoustic near-field, where such displays are experienced in vivo. When peacock wing-shaking courtship behaviour was simulated in the laboratory, the resulting directional airflow excited measurable vibrations of crest feathers. These results suggest that peafowl crests have properties that make them suitable mechanosensors for airborne stimuli generated during social displays. Such stimuli could complement acoustic perception, thereby enhancing detection and interpretation of social displays. Diverse feather crests are found in many bird species that perform similar displays, suggesting that this proposed sensory modality may be widespread, and possibly derived from flow sensing in other contexts. We suggest behavioral studies to further explore these ideas and their functional implications.
Summary statement Avian crest feathers have mechanical properties that make them suitable for sensing airflows generated during multimodal social displays.