Chameleon Communication

By Donald L. Blanchard

Ken Barnett was handling Zappa, his pet veiled chameleon (Chamaeleo calyptratus) one day, when he noticed that it was producing a buzzing sound from an area just in front of its front legs. Insects are known to communicate by producing vibrations which are transmitted along twigs and branches. Although such communications have never been reported among reptiles, Barnett suspected that something similar might occur with chameleons.

In a report published in Copeia and reprinted (with permission) in the May, 1999 issue of Herp Beat, the newsletter of the Upstate (NY) Herpetological Association, Ken, along with Reginald Cocroft and Leo Fleishman, report their findings.

Ken and his co-workers attached a sensitive accelerometer to one branch of a small branching shrub. A hand-reared adult male chameleon was then placed on the branch, approximately 4 inches (10 cm) from the accelerometer. With the male alone and undisturbed, no vibrations were detected. However, when a receptive female was placed on the same branch, the male commenced a courtship display, changing its coloration, flattening its body, and approached the female. As it did so, it also produced a series of vibrational signals; 137 of them over a period of just over an hour were recorded.

Signals were produced in groups of 1 to 14, each typically beginning with a series of high-pitched short signals followed by one longer one. While the signals varied significantly, the shorter high-pitched sounds generally sere above 105 Hz, and lasted less than two tenths of a second. The longer, lower-pitched signals typically lasted close to a second, and were below 90 Hz. (These frequencies would lie comfortably within the vocal range of a baritone singer. --dlb)

None of these signals were audible to a person standing about 3 feet (1 m) distant from the lizard. Previous studies on chameleons have reported that the lizards are less sensitive to airborne sounds than humans, which suggests that the lizards in the study, if they were able to detect vibrations at all, must have been doing so by way of transmission through the branch.

Signals were also produced, both by the male and the female, when the lizard was lightly touched at the base of the tail. These signals were similar in characteristics to the shorter signals described above, but were faintly audible to a researcher immediately adjacent to the lizards.

The authors report that vibration in response to a direct touch has been reported previously in two other genera of chameleons, and concludes that vibrational communications of the sort detected may occur in many members of the chameleon family.

References:
Barnett, Kenneth E., Reginald B. Cocroft, and Leo J. Fleishman. Possible Communication by Substrate Vibration in a Chameleon. Herp Beat, Vol. 10, Issue 5, May, 1999.