CALL DIVERSITY IN AN OLD WORLD TREEFROG: LEVEL DEPENDENCE AND LATENCY OF ACOUSTIC RESPONSES

Abstract

ABSTRACT We studied the calling behaviour of the southeast Asian treefrog Polypedates leucomystax in the field. The spontaneous calling rate of isolated males was less than 3 calls/minute with irregular temporal patterning of their calls. Call diversity was very high with nine different call notes and at least 12 different call types recorded. 49% of the 1344 calls recorded were so-called “normal calls”. Isolated males produce normal calls almost exclusively, and females were attracted to males that only emitted this call. All other calls appear to mediate male-male interactions. The frogs responded to playbacks at stimulus levels below 70 dB SPL by increasing the number and diversity of calls. At higher stimulus levels, the evoked calling rate decreased. The latency between stimulus and response depended on the call type of the response. Some of the call types follow the stimulus with a latency of < 1 s. It is unlikely that the short latency responses in P. leucomystax function to avoid call overlap as reported for other frog species, since in this species calling is infrequent and aperiodic. Instead, short response latencies probably reflect increased levels of aggression directed towards the first caller. Thus, response latency itself may have a signal function.