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Frogs Call at a Higher Pitch in Traffic Noise

Frogs Call at a Higher Pitch in Traffic Noise,Kirsten M. Parris,Meah Velik-lord,Joanne M. A. North

Frogs Call at a Higher Pitch in Traffic Noise   (Citations: 13)
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ABSTRACT. Male frogs call to attract females for mating and to defend territories from rival males. Female frogs of some species prefer lower-pitched calls, which indicate larger, more experienced males. Acoustic interference occurs when,background,noise reduces the active distance or the distance over which an acoustic signal can be detected. Birds are known to call at a higher pitch or frequency in urban noise, decreasing acoustic interference from low-frequency noise. Using Bayesian linear regression, we investigated the effect of traffic noise on the pitch of advertisementcalls in two species of frogs, the southern brown tree frog (Litoria ewingii) and the common,eastern froglet (Crinia signifera). We found evidence that L. ewingiicalls at a higher pitch in traffic noise, with an average increase in dominant frequency of 4.1 Hz/dB of traffic noise, and a total effect size of 123 Hz. This frequency shift is smaller than that observed in birds, but is still large enough to be detected by conspecific frogs and confer a significant benefit to the caller. Mathematical modelling predicted a 24% increase in the active distance of a L. ewingiicall in traffic noise with a frequency shift of this size. Crinia signiferamay also call at a higher pitch in traffic noise, but more data are required to be confident of this effect. Because frog calls are innate rather than learned, the frequency shift demonstrated,by L. ewingiimay,represent an evolutionary adaptation to noisy conditions. The phenomenon,of frogs calling at a higher pitch in traffic noise could therefore constitute an intriguing trade-off between audibility and attractiveness to potential mates. Key Words: acoustic interference; ambient noise; amphibian,decline; animal behavior; bioacoustics; road
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    • ...) and which lack the vocal flexibility to make frequency (kHz) adjustments (calls are usually innate and are therefore expected to be less ‘flexible’ than learnt vocalizations such as song; ...

    Hélène Lowryet al. How Noisy Does a Noisy Miner Have to Be? Amplitude Adjustments of Alar...

    • ...Interest in the impacts of noise on ecosystems has burgeoned recently and noise-related effects on physiology, behaviour, spatial distribution and interactions have been demonstrated (Slabbekoorn and Peet 2003; Rabin et al. 2006; Brumm et al. 2007; Parris et al. 2009; Francis et al. 2009)...
    • ...Anyhow, it is undeniable that underpass entrances, and motorway surroundings in general, are currently subject to noise levels that are capable of causing a range of negative effects on physiology, behaviour and interactions amongst vertebrate species (Slabbekoorn and Peet 2003; Parris et al. 2009; Barber et al. 2010)...
    • ...Environmental noise, at the levels detected in this study, is known to affect vocal communication in species that depend on it (Slabbekoorn and Peet 2003; Brumm et al. 2007; Parris et al. 2009), and it may determine the speciescomposition of a community (Francis et al. 2009)...

    Carlos Iglesiaset al. The Influence of Traffic Noise on Vertebrate Road Crossing Through Und...

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