Effects of traffic noise on vocalisations of the rhacophorid tree frog Kurixalus chaseni (Anura: Rhacophoridae) in Borneo

Transportation networks are currently growing at rapid rates, and the increase in roads can have detrimental effects on biodiversity. Increases in anthropogenic noise have been demonstrated to negatively impact several types of behaviour across taxa, as well as to mask key elements of vocalisations required for communication. While much information has been collected for species in temperate regions, fewer data are available for Southeast (SE) Asian species. Given that SE Asia has the highest rate of deforestation, which is the largest driver of road expansion, more data are needed on the impacts of traffic noise on SE Asian species. To that end, we exposed calling tree frogs (Kurixalus chaseni) to traffic noise to determine the impacts of two levels (low and high) of anthropogenic noise on dominant frequency, mean amplitude, and signal rates. While there was no observed impact of exposure to low traffic noise, we observed an increase in mean call amplitude when frogs were exposed to high traffic noise. Increased amplitude is energetically expensive compared to changes in frequency or signal rate, which indicates that increased traffic noise may have negative impacts on long-term fitness in this species. We encourage further studies on the relationship between traffic noise and reproduction in this and other species across the region.