Traffic noise differentially impacts call types in a Japanese treefrog (Buergeria japonica)

Abstract

Acoustic noise from automobile traffic impedes communication between signaling animals. To overcome the acoustic interference imposed by anthropogenic noise, species across taxa adjust their signaling behavior to increase signal saliency. As most of the spectral energy of anthropogenic noise is concentrated at low acoustic frequencies, species with lower frequency signals are expected to be more affected. Thus, species with low‐frequency signals are under stronger pressure to adjust their signaling behaviors to avoid auditory masking than species with higher frequency signals. Similarly, for a species with multiple types of signals that differ in spectral characteristics, different signal types are expected to be differentially masked. We investigate how the different call types of a Japanese stream breeding treefrog (Buergeria japonica) are affected by automobile traffic noise. Male B. japonica produce two call types that differ in their spectral elements, a Type I call with lower dominant frequency and a Type II call with higher dominant frequency. In response to acoustic playbacks of traffic noise, B. japonica reduced the duration of their Type I calls, but not Type II calls. In addition, B. japonica increased the call effort of their Type I calls and decreased the call effort of their Type II calls. This result contrasts with prior studies in other taxa, which suggest that signalers may switch to higher frequency signal types in response to traffic noise. Furthermore, the increase in Type I call effort was only a short‐term response to noise, while reduced Type II call effort persisted after the playbacks had ended. Overall, such differential effects on signal types suggest that some social functions will be disrupted more than others. By considering the effects of anthropogenic noise across multiple signal types, these results provide a more in‐depth understanding of the behavioral impacts of anthropogenic noise within a species.

Calling and foot‐flagging: Territory competition behavior of two male Buergeria otai

“…My observation showed that B. otai used a combination of visual and vocal cues in a competition for signaling site and that long calls used in the competition were distinct from normal advertisement calls (Legett et al, 2020a; Wang et al, 2017). If Buergeria otai alters the call types to coordinate with different behaviors warrants further examination (Legett et al, 2020b).…”

Potential effects of traffic noise on anuran call characteristics in Louisiana, USA during winter

“…Most male anurans produce advertisement calls to attract mates and defend territories (Gerhardt, 1994 ; Lee et al., 2023 ) but traffic noise overlaps many species' frequency niches and has high amplitude (Bee & Swanson, 2007 ; Cunnington & Fahrig, 2010 ; Grace & Noss, 2018 ), which can mask anuran vocalizations (Bee & Swanson, 2007 ; Lee et al., 2023 ). To compensate for traffic noise, some species increase the dominant frequency (Caorsi et al., 2017 ; Grenat et al., 2019 ; Leon et al., 2019 ), amplitude (Halfwerk et al., 2016 ; Leon et al., 2019 ), call rate (Cunnington & Fahrig, 2010 ; Grenat et al., 2019 ; Legett et al., 2020 ), or number of notes (Grace & Noss, 2018 ; Leon et al., 2019 ) of their vocalizations, whereas others avoid calling during periods of high background noise (Vargas‐Salinas & Amézquita, 2013 ). Though these strategies can improve vocalization audibility, changing call characteristics can be energetically costly, constrained by physiology, and can increase predation risk (Gerhardt, 1994 ).…”

Influence of Conspecifics and Road Noise on the Properties of the Advertisement Call of Phyllodytes Luteolus (Anura, Hylidae)

“…Among the strategies used by anurans to reduce or avoid the overlap between biotic and anthropic noises on their calls, there are changes in amplitude (Halfwerk et al, 2016;Parris et al, 2009;Yi & Sheridan, 2019), frequency (Caorsi et al, 2017;Cunnington & Fahrig, 2010), duration (Zhao et al, 2021) and emission rate (Hanna et al, 2014;Kaiser & Hammers, 2009;Legett et al, 2020). These changes can be advantageous when the individuals are under external influences, since the acoustic signals indicate physical condition of the individuals.…”