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 locate a
speaker playing conspecific male song in four background acoustic
conditions: silence, road noise, river noise, and heterospecific song. We
recorded how successful crickets were in reaching the correct speaker in
each condition, as well as varying other metrics for the ones that were
successful, such as speed, path length and latency to start. Crickets
paused more frequently during river noise and heterospecific song
treatments compared to silence or road noise. We also recorded auditory
interneuron (AN2) activity under the first three background conditions to
construct and compare condition-specific audiograms and AN2 response to
conspecific song. We examined the the thresholds of response for AN2 at
difference frequencies and how responsive it was to male under said noise
conditions. AN2 thresholds for 6 kHz sounds (the frequency close to male
song frequency) were highest in river noise, while heterospecific song
increased baseline AN2 activity and reduced AN2 activity to conspecific
song onset. Together, our results suggest road noise is not a
qualitatively greater disturbance than is river noise.