Traffic Noise Affects Brazilian Mundo Novo Treefrog Calling Behavior

Abstract

Anthropogenic disturbance, including noise, is a major cause of biodiversity decline worldwide. Especially in anurans, the effect of noise pollution is known to have major consequences on their reproduction since acoustic communication is an essential part of this process. In this study, we tested the effect of three levels of traffic noise (55 dB, 65 dB, and 75 dB) corresponding to three different distances from the road (200, 100, and 50 m, respectively) on the Brazilian Mundo Novo treefrog (Boana marginata). The results of the playback experiments showed an effect on call type B. More specifically, there was a decrease in the advertisement call rate, a reduction in the number of pulses, and a lengthening of the interval between pulses, particularly at 65 dB. These findings suggest that at distances of up to 100 m, the masking effect significantly influences acoustic communication on the species. However, a 55 dB stimulus—equal to 200 m from the road edge—did not change the call in this species, suggesting a minimal distance to implement noise-inflicting infrastructures. We recommend that new studies adopt sampling methods from this distance to refine the threshold of the traffic noise effect.