Song duration and female response behaviour in the grasshopper Omocestus viridulus

Abstract

Abstract. The calling song of male grasshoppers of the genus Omocestus has a highly species-specific duration. Two playback experiments were conducted to investigate how variation in song duration affected female response. Females responded more readily and with longer stridulations to longer male songs. There was, however, a diminishing return in the female response so a male will gain less and less by singing longer songs. Repetition of short songs, with the same total duration as a long song, elicited a similar or even more intense response. Females did not necessarily wait for a male song to finish before responding with stridulation. A majority of the females had already started to respond when a long song ended. However, the females spent more time moving, probably towards the singing male, as a response to longer songs. These results suggest that the duration of individual songs is not important per se in evoking female response, and that a male seems to evoke most response by singing as much as possible. However, to maximize the efficiency of his singing, he must also time his songs to decrease the overlap with the female's response singing, and increase the probability of hearing her response.