Rivers and roads, silence and songs: female crickets respond similarly to conspecific male song in natural and anthropogenic soundscapes.

Many studies have demonstrated that anthropogenic noise affects animals' auditory perception of salient stimuli. Few have tested whether these effects are different from those experienced in nature. We tested the ability of female field crickets, Teleogryllus oceanicus, to phonotactically locate a speaker playing conspecific male song in four acoustic backgrounds: silence, road noise, river noise and heterospecific song. Crickets approaching conspecific song paused more frequently in river noise and heterospecific song treatments compared with silence or road noise. We also recorded auditory interneuron (AN1 and AN2) activity under the first three acoustic background treatments to construct and compare treatment-specific audiograms and interneuron responses to conspecific song. We found little difference in activity, other than that AN2 thresholds for 6 kHz sounds (the tested frequency closest to male song) were highest in river noise, while heterospecific song increased baseline AN2 activity and reduced AN2 activity to conspecific song onset. Our results suggest road noise is not necessarily a greater disturbance than river noise.