Mate attraction by male anurans in the presence of traffic noise

Abstract

We previously found that males of two anuran species – Hyla versicolor and Rana clamitans – alter their mating calls in response to traffic noise. To test whether these alterations compensate for an effect of traffic noise on mate attraction, we (1) recorded a male calling at a quiet site; (2) played traffic noise at the same male and recorded its altered call; (3) used these recordings to attract females to a trap at sites either with or without broadcast traffic noise. The calls produced without traffic noise attracted fewer females when they were played at sites with traffic noise than when they were played at sites without noise. However, the calls of the same individuals produced with traffic noise attracted as many females at sites with noise as at sites without noise, and they attracted as many females as did the call of the same male made without noise and played at sites without noise (the ‘natural’ situation). Therefore, for these species, traffic noise does not affect mate attraction; males change their calls to compensate for a potential effect of traffic noise on mate attraction. A third species – Bufo americanus – does not alter its call in response to traffic noise, and its call made in the absence or presence of traffic noise was equally able to attract females in the absence or presence of traffic noise, indicating that traffic noise does not negatively affect mate attraction. Therefore, it appears that traffic noise does not negatively affect mate attraction in these three species of anurans. We suggest that, if our results apply to anurans in general, the previously documented negative effects of roads on anuran populations are likely caused mainly by road mortality. If this is true, road mitigation for anurans should focus mainly on reducing this mortality.

Suffering in receivers: Negative effects of noise persist regardless of experience in female anurans

“…The importance of our findings is twofold: One is that noise pollution can have substantial and prevalent negative impacts on signal receivers, and possibly on any animals with hearing abilities that overlap frequencies dominated by anthropogenic noise. Even if signallers mitigate masking effects of noise by altering their calls (Cunnington & Fahrig, ; Francis et al., ; Nemeth et al., ), impacts of noise on communication and therefore ultimately on fitness may persist through the chronic distracting or aversive effects on signal receivers. Indeed, the impacts of noise on anurans detected here (i.e., late arrival to breeding sites and disorientated phonotaxis) can cause lower fitness via reduction in mating success, fertilization and survival (Tennessen, Parks, & Langkilde, ).…”

“…Males of several anuran species can alter the frequency of their call in the presence of low‐frequency traffic noise to reduce its masking effect (Bee & Swanson, ; Kaiser & Hammers, ; Parris, Velik‐lord, & North, ), and frequency‐shifted calls are more attractive for females in noise (Cunnington & Fahrig, ). However, our preliminary tests showed that our model species did not have such ability (Appendix S1).…”

“…Detrimental effects of noise, however, can be mitigated by behavioural and phenotypic plasticity of animals against noise (Lampe, Reinhold, & Schmoll, ; LaZerte, Slabbekoorn, & Otter, ). Indeed, there is plenty of evidence showing that signallers can reduce negative effects of acoustic masking by modifying their signal properties such as frequencies (Cunnington & Fahrig, ; Francis, Ortega, & Cruz, ; Patricelli & Blickley, ; Slabbekoorn & Peet, ) or amplitudes (i.e., the Lombard effects) (Halfwerk, Lea, Guerra, Page, & Ryan, ; Zollinger & Brumm, ). Moreover, recent studies have shown that prior experience with noise can be related to such modifiability in signallers (Gentry, Derryberry, Danner, Danner, & Luther, ; LaZerte et al., ).…”

“…Indeed, there is plenty of evidence showing that signallers can reduce negative effects of acoustic masking by modifying their signal properties such as frequencies (Cunnington & Fahrig, 2013;Francis, Ortega, & Cruz, 2011;Patricelli & Blickley, 2006;Slabbekoorn & Peet, 2003) or amplitudes (i.e., the Lombard effects) (Halfwerk, Lea, Guerra, Page, & Ryan, 2016;Zollinger & Brumm, 2011). Moreover, recent studies have shown that prior experience with noise can be related to such modifiability in signallers LaZerte et al, 2016).…”

“…Specifically, we use female phonotaxis towards male advertisement calls in an anuran species as the model system. Anurans have cosmopolitan distributions, and female phonotaxis in anurans is directly relevant to their reproductive success (Bee, 2008;Bee, Kozich, Blackwell, & Carl Gerhardt, 2001;Cunnington & Fahrig, 2013;Lee, Ward, Vélez, Micheyl, & Bee, 2017;Moreno-Gómez, Sueur, Soto-Gamboa, & Penna, 2013). Based on previous studies (LaZerte et al, 2016;Luo et al, 2015), the experiment was designed as follows: gravid females were collected from quiet and traffic noise-exposed wetlands.…”