Acoustic satellite behaviour in the Australian bushcricket Elephantodeta nobilis (Phaneropterinae, Tettigoniidae, Orthoptera)

Abstract

Male and female Elephantodeta nobilis duet with the female responding to the male's long and complex call. The duetting male's call consisted of four parts, described here as parts A, B, C and D. We found that the female replied 570ms after the male's D pulse, which followed the extended part B and short click of part C. Noncalling males were attracted to the duet and often used satellite tactics by inserting a volley of clicks 200ms before the alpha male's D pulse. Satellite males used part C of the alpha male song to cue their own call and this inserted call induced females to reply earlier compared with the alpha male call alone. Alpha males often extended their calls with additional D-type calls and so we examined the effectiveness of these calls as countermeasures to satellite calling. There was no influence of this alpha strategy on the satellite's propensity to call although more calls from the alpha male did cause the female to reply more frequently. We also examined the effect of relative intensity of alpha and satellite calls on the female's reply. Reduced satellite intensity increased the variance in the timing of the female response. Finally, we tested the effectiveness of the satellite's call on female phonotaxis within a two-speaker arena. Although females preferred the alpha male they were nevertheless attracted to the satellite calls regardless of the latter's relative intensity. We discuss the possible role of satellite calling as a novel conditional strategy.