The effect of anthropogenic noise on male advertisement call rate in the neotropical treefrog, Dendropsophus triangulum

Anthropogenic change such as road construction and subsequent traffic noise in pristine habitats has been shown to be detrimental to a range of vertebrate taxa. The effect of anthropogenic noise on anuran communication is not well known, and has only recently been a topic of investigation. We tested the effect of anthropogenic noise on the calling behaviour of the Amazonian treefrog Dendropsophus triangulum. We performed four experiments. We first presented frogs with the noise of a pre-recorded motorcycle engine, and recorded the call rates of focal frogs for 5 min, then for another 5 min during which they were presented with a broadcast of noise, and again for 5 min post-stimulus. We repeated this experiment using music as the stimulus. We then tested the effect of intermittent engine noise, recording baseline call rate and response to six cycles of intermittent noise. In all experiments, call rates nearly doubled during playbacks. Finally, we compared frogs' responses to anthropogenic noise to responses to chorus noise broadcast at the same intensity; call rates did not differ between treatments. These results demonstrate a clear effect of exogenous noise on male D. triangulum.