ACOUSTIC SIGNALS OF THE NOCTURNAL LIZARD GEKKO GECKO: ANALYSIS OF THE ‘LONG COMPLEX SEQUENCE’

ABSTRACT

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 1m 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 bi-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.