Nightly Calling Durations of Male Sagebrush Crickets, Cyphoderris strepitans: Size, Mating and Seasonal Effects

Abstract

Male sagebrush crickets (Cyphoderris strepitans) provide their mates with two forms of nutrient investment at mating: 1) while coupled, the female consumes a portion of the male's hind wings and ingests haemolymph oozing from the wound and 2) the female consumes the externally attached spermatophore some time after copulation. We examined the effect of this large nutrient investment on the ability of males to sustain calling after a mating. Calling activity of males was monitored using an electronic sound-activated relay apparatus. Nightly calling durations of recently mated males were significantly reduced relative to those of virgin males, after the effects of male body mass and sampling date had been removed. Non-virgin males, having lost a substantial portion of available energy reserves through mating, may lack the resources required to sustain calling at pre-mating levels. Nightly calling durations of virgin males exhibited a significant seasonal decline. Acoustic signalling probably depletes energy reserves that are not replenished because of reduced foraging opportunities. Virgin male body mass was positively correlated with calling duration suggesting that larger males possess greater resources to sustain a more expensive signal. These results demonstrate that male investment at mating is not always trivial, and may detract significantly from other costly forms of mating effort, particularly acoustic signalling behavior.