Acoustic behavior of the gekkonid lizard, Hemidactylus frenatus

The present study demonstrates that Hemidactyltis frenatus has a vocal repertory of three functionally, physically distinct calls that are important in its social behavior. The multiple chirp (MC) call is the most common and is closely associated with agonistic behavior and territorial defense. The MC call has a consistent temporal pattern of chirps, and call rate varies directly with air temperature. Die1 calling periodicity was investigated for the MC call and calls were observed to increase from dusk to a high in the early morning hours. Increasing call counts were positively correlated with numbers of active geckos. The churr call is infrequently heard, occurring only during aggressive encounters between $ $, and is thought to function as intimidation. The single chirp (SC) call is frequently heard and is closely associated with distress. The SC call may facilitate escape from predators. The acoustic behavior of H. jrenatus is compared to that of other species of geckos and some correlates found. MOST reptiles do not utilize sounds as produce distinct vocalizations. The family intraspecific comn~unication signals, but at Gekkonidae is noted for its vocal abilities least some members of the four major surwhich are thought to be of importance in viving orders have been reported to vocalintraspecific communication. ize in social situations (Busnel, 1963). In The significance of gccko sounds has most lizards sound production is lacking, been a source of controversy and specuor is limited to hissing, but a few can lation for years. Functional suggestions HERPETOLOCICA 30:44-52. March, 1974 March. 19741 HERPETOLOGICA 45 range from attraction of insects (Beebe, 1944) to the more plausible possibility that the calls function in social behavior (Brain, 1962; Evans, 1936; Mertens, 1955; Petzold, 1965; Wever et a]., 1963a). Evans (1936) was one of the first to state that a species of gecko was able to make more than one type of sound, but until recently no description or analysis of gecko calls had been published. In 1969 Haacke described the calls of three species of South African geckos of the genus Ftenopus, and his paper remains as the only attempt to work quantitatively with gecko acoustic behavior. The present paper describes the calls and documents some aspects of the acoustic behavior of Hemidactylus frenatus.