Male Field Cricket Songs Are Altered After Aggressive Interactions

To address the hypothesis that male acoustic sexual advertisement signals, in addition to chemical signals, might be indicators of aggressiveness, we examined the relationship between levels of aggression/dominance status and acoustic sexual advertisement signals in the field cricket Gryllus integer. Males were paired in aggression trials and recorded the night before and night after the trial. This allowed us to test whether aggression is inherently linked to song phenotypes, or whether aggressive interactions cause males to alter their songs. We found that dominant (winning) males signaled with higher energy, amplitude, and power the night after winning an aggressive encounter, but we could not detect any differences before the encounter. Time spent calling and the number of calling bouts were apparently unrelated to aggression, whereas winning males increased their bout lengths after winning, and losing males decreased their bout lengths after losing.