Vocal repertoire and effect of advertisement call intensity on calling behaviour in the West African tree frog, Leptopelis viridis

Abstract

AbstractThe vocal repertoire of the West African tree frog Leptopelis viridis was investigated in the Comoé National Park, Ivory Coast. Leptopelis viridis had a complex vocal repertoire consisting of short clicks, multinote clicks, trills, and soft calls. Most calls produced were short advertisement clicks. Soft calls were emitted during agonistic interactions between males suggesting that they function as aggressive calls. In contrast, multinote calls and trills were emitted when advertisement call rate was high suggesting that these calls are used by males to increase their attractiveness to females. Even at high densities males were spaced widely with a median nearest neighbour distance of 4.8 m. We also examined the effects of increased sound level of advertisement calls on calling behaviour. Playback experiments using synthetic clicks showed that males increased the proportion of aggressive calls as the stimulus intensity was increased. Males typically responded with aggressive calls when playback levels exceeded 82 dB (re 20 μPa). At high playback levels males either aggressively approached the speaker or silently retreated.