Pursuit deterrent signalling by the bonaire whiptail lizard Cnemidophorus murinus

Abstract Pursuit-deterrent signalling may account for several behaviors, often subtle, that have no current satisfactory explanation. We conducted field observations and experiments to determine whether arm-waving by Bonaire whiptail lizards, Cnemidophorus murinus, is consistent with pursuit deterrent signalling. The hypotheses that lizards wave their arms to remove feet from hot substrates and that arm-waving is solely a social signal were falsified. Lizards preferentially waved the arm closer to an investigator simulating a predator, typically while looking directly at the predator. This strongly suggests signalling and contradicts the hypothesis that arm-waving is merely a flight intention movement. Most individuals retreat, providing a margin of safety, and then wave. As expected for a pursuit-deterrent signal, arm-waving is related to risk. During direct approaches lizards waved when the predator drew within 3-6 m if approached slowly, but fled without signalling if approached rapidly. Lizards approached tangentially signalled frequently when the minimum bypass distance was 2-4 m, but rarely when it was 10 m. They arm-waved when predators approached, but rarely while they retreated. Arm-waving was rare where lizards were habituated to human presence, but frequent elsewhere. Collectively, the data strongly suggest that arm-waving has a pursuit-deterrent function.