Response ofAnolis sagreito Acoustic Calls from Predatory and Nonpredatory Birds

Lisa R. Cantwell, T. G. Forrest
2013 Journal of Herpetology  
Predation is one of many selective forces driving evolution in prey organisms. Studies indicate that vertebrates and invertebrates use sensory cues to recognize predators and evaluate predation risk. Lizards and birds frequently inhabit the same ecosystems; consequently, avian predation on lizards has been implicated as an important selective pressure on lizard behavior. However, no studies have been conducted on anole response to non-visual cues. Male anoles exhibit characteristics that
more » ... e their vulnerability to predatory birds including conspicuous coloration and behavioral displays. They also posses well developed auditory systems with enhanced directionality. Interestingly, lizards are non-vocal animals and therefore their auditory systems must function for something other than intraspecific communication with likely functions including the detection of prey or predators. The response of adult male brown anoles (Anolis sagrei) to calls of birds was studied to determine whether they use auditory cues as an indicator of predation risk from birds. Anole responses (no reaction, eye movement, head tilt, and run to cover) varied among stimuli and were significantly dependent on the stimulus presented (G=69.9, P<<0.001). More than half of the 32 anoles did not respond to playbacks of non-predatory birds or white noise (Cardinal: N=20; Finch: N=19; Sparrow: N=18; Thrasher: N=16; white noise: N=18), whereas less than a third of the anoles did not respond to playbacks of predatory kestrel calls (N=8) or hawk calls (N=11). Anoles reacted with anti-predator behavior more often to high risk stimuli compared to non-threatening stimuli. Anoles responded significantly more often with head tilt, suggesting predator recognition, during playback of predatory vocalizations (kestrel: N=15, G=17.76, P<0.001; hawk: N=12, G=9.61, P<0.025) than to low risk stimuli (non-predatory bird calls, white noise and thrasher). Results indicate that anoles distinguish predatory from non-predatory birds by means of acoustic cues.
doi:10.1670/11-184 fatcat:mrwbcptcxfb6zpy2mwfgnlk77y