Investigations of Biotremors in the Veiled Chameleon (Chamaeleo calyptratus)

While substrate-borne vibrations are utilized by different reptile species, true conspecific communication via biotremors has not yet been demonstrated in reptiles. This study follows a preliminary report that the veiled chameleon (Chamaeleo calyptratus) could produce biotremors in communicative contexts. I tested chameleon behavioral sensitivity to vibrations by placing them on a dowel attached to a shaker emitting vibrations of 25, 50, 150, 300, and 600 Hz and then measured their changes in velocity before and after the stimulus. I then paired chameleons in various social contexts [anthropogenic disturbance (human disruption of animal); dominance (malemale; female-female C. calyptratus); courtship (male-female C. calyptratus); heterospecific (C. calyptratus + C. gracilis); and predator-prey (adult + juvenile C. calyptratus)] and used a video camera and accelerometers to record their behavior. This study demonstrates that chameleons produce biotremors and that receivers exhibit a freeze response when exposed to a simulated biotremor stimulus. Furthermore, veiled chameleons produce biotremors in anthropogenic disturbance, conspecific dominance and courtship contexts, and these biotremors are elicited by visual contact with another adult conspecific and heterospecifics. Overall, two classes of biotremor were identified, hoots” and “rumbles,” which differ significantly in dominant frequency and waveform. No correlation was identified between animal size and dominant frequency of the biotremors they produced as biotremors originate from rapid muscle contractions. Juvenile chameleons of two months of age are able to produce biotremors, suggesting this behavior may have multiple functions. Overall, the data suggest that the veiled chameleon has the potential to utilize substrate-borne vibrational communication during conspecific and possibly heterospecific interactions