The Hearing of Geckos

Abstract

Geckos are found world wide in almost all regions which are relatively warm. The largest grow to a length of about 34 cm. Most are nocturnal and are able to climb on vertical surfaces and even upside down, thanks to their specialized finger-tip pads. Geckos form one of the most interesting families of lizards from the point of view of their hearing, for they are the only lizards that use strong vocalizations. These are chirps, croaks or barks that are used in intraspecific communication and as aggressive warning sounds (Frankenberg, 1975; Marcel-lini, 1977; Werner et al., 1978). Their signals have a pronounced time structure, which forms an optimal stimulus for the gecko inner ear (see below). It is possible that this usage of the auditory system developed in combination with their predominantly nocturnal or crepuscular way of life. The geckos also represent the only case in which we know of another clear usage of the auditory system in the life of lizards. Sakaluk and Belwood (1984) report that Mediterranean house geckos (Hemidactylus tursicus) exhibit positive phonotaxis to a loudspeaker broadcasting cricket calling song. In the field, these geckos are found close to the burrows of calling male crickets, a behaviour which enables them to intercept female crickets attracted by the male’s call.