Traffic noise exposure impacts song production in wild male field crickets (Gryllus bimaculatus) under predator and intrasexual competition contexts

Animals are known to adjust their acoustic signals in the presence of anthropogenic noise. These changes may affect fitness by altering susceptibility to predators or changing signal efficiency in intra and intersexual interactions. Male field crickets, Gryllus bimaculatus, chirp to attract females, with chirp rate being an important success factor. Males reduce chirp rate when exposed to predators or traffic noise and increase it in response to male competitors. However, the combined effects of these pressures on signalling are unknown. This study examined whether antipredator responses are influenced by male-male competition and variation in traffic noise exposure. We used substrate-borne vibrations to simulate a predator approaching calling males and varied perceived male-male competition using playbacks. We found that responses to increased competition were affected by variation in traffic noise exposure, with males chirping faster as noise levels increased. Additionally, antipredator responses depended on an interaction between traffic noise and competition. Under high competition, males reduced chirp rate as traffic noise increased. Our results demonstrate that adjustments in signal production in response to noise pollution may negatively impact communication in both antipredator and competitive contexts, indicating more pervasive effects of anthropogenic noise than previously recognized.