reptiles

Four types of vocalizations uttered by the nocturnal Lizard Gekko gecko (the "Tokay'') are described. A bark of intimidation, distress calls, a short not very intense call, apparently related to sexual inter-action, and a long, complex sequence. This "long sequence'' is considered as a territorial proclamation which functions also as a mating-call. This call has been analysed in detail with special emphasis on the intra-individual variations. The mean duration of this sequence is 22.3 s, the intensity is 70 do at lm and the maximum of energy is between 300 and 400 Hz. This sequence is composed of three phases. The first one consists of several "roulades'', the second, of bi-motifs which sound like two syllables tok-kay, and the third, not always present, is a kind of "rattle''. The number of motifs and the occurrence of the 3rd phase vary in the sequence of an individual, but the duration of the motifs is relatively stable.

Four types of vocalizations of the nocturnal lizard Gekko gecko (the 'Tokay') are described. A bark of intimidation, distress calls, a short not very intense call, apparently related to sexual inter-action, and a long, complex sequence. This ‘long sequence’ is considered to be a territorial proclamation which also functions as a mating-call. It has been analysed in detail with special emphasis on the intra-individual variations. The mean duration of this sequence is 22.3 s, the intensity is 70 dB at lm and the maximum of energy is between 300 and 4000 Hz. This sequence is composed of three phases. The first one consists of several multipulse sounds called 'rattles', the second of hi-motifs which sound like a two syllable tok-kay, and the third, not always present, is a kind of ‘grumble’. The number of motifs and the occurrence of the third phase may vary but the duration of the motifs is relatively stable.

Based on nine calls of Calodactylodes illingworthorum recorded in the wild in Sri Lanka, the ‘spontaneous’ call of the species is a very rapid series of 4-7 roughly similar chirps. Call parameters are compared to those of Ptyodactylus guttatus of Israel because the species are similar in morphology (size, proportions, digit shape, scutellation, coloration), ecology (rupicolous, nocturnal), and reproductive biology (clutches of two eggs, stuck to rock, in ‘rookeries’). The calls of the two species, despite similarity in basic structure, greatly differ in the number of chirps, chirp repetition rate, total duration, dominant frequency, and relative intensity level. The functional implications of these differences are briefly considered.