The effect of anthropogenic noise and weather conditions on male calls in the bladder grasshopper Bullacris unicolor

Abstract

Acoustic communication in animals relies upon specificcontextsandenvironments for effective signal transmission. Increasing anthropo-genic noise pollution and different weather conditions can disruptacoustic communication. In this study, we investigated call parameterdifferences in the bladder grasshopperBullacris unicolorinhabitingtwo sites in close proximity to each other that differed in their noiselevels. Calling activity was monitored via passive acoustic recorders.Weather conditions, including wind speed, temperature and humid-ity, were also recorded. We found that the interval between succes-sive calls increased with higher noise levels at both sites, and the peakfrequency became lower. The total number of calls detected alsodecreased with anthropogenic noise, but this relationship was onlyevident at the noisier site. In addition, grasshoppers shifted the timingof their calls to later in the night at the noisier site, possibly to takeadvantage of relatively lower noise levels.