Possible communication by substrate vibration in a chameleon

Plant-borne vibration is a common mode of communication among insects, but its use in reptiles has never previously been reported. One of us (KEB) observed that in response to human touch, veiled chameleons (Chamaeleo calyptratus) produce a distinct vibration which emanates from the body just anterior to the front legs. We made accelerometer recordings from plants on which chameleons were placed and determined that conspicuous vibratory signals were produced by males and females in response to human touch. When an adult male was placed on a plant with an adult female, it produced a variety of vibratory signals which varied in their gross-temporal and frequency characteristics. We hypothesize that these vibrations serve as vegetation-borne vibratory communication signals because (1) they were barely audible or inaudible to humans, whose auditory sensitivity exceeds that of chameleons but were easily detected by the accelerometer attached to a plant at 0.1 m distance and (2) they were produced in courtship and disturbance contexts in which one might expect communication to take place.