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Anthropogenic noise disrupts use of vocal information about predation risk

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)988-995
Number of pages8
JournalEnvironmental Pollution
Early online date29 Aug 2016
DateAccepted/In press - 20 Aug 2016
DateE-pub ahead of print - 29 Aug 2016
DatePublished (current) - 1 Nov 2016


Anthropogenic (man-made) noise is rapidly becoming an universal environmental feature. While the impacts of such additional noise on avian sexual signals are well documented, our understanding of its effect in other terrestrial taxa, on other vocalisations, and on receivers is more limited. Little is known, for example, about the influence of anthropogenic noise on responses to vocalisations relating to predation risk, despite the potential fitness consequences. We use playback experiments to investigate the impact of traffic noise on the responses of foraging dwarf mongooses (Helogale parvula) to surveillance calls produced by sentinels, individuals scanning for danger from a raised position whose presence usually results in reduced vigilance by foragers. Foragers exposed to surveillance calls in traffic-noise compared to ambient-noise playback exhibited a lessened response (increased personal vigilance). A second playback experiment, using noise playbacks without surveillance calls, suggests that the increased vigilance could arise in part from the direct influence of additional noise (the ‘increased threat hypothesis’) as there was an increase in response to traffic-noise playback alone. Acoustic masking could also play a role. Foragers maintained the ability to distinguish between sentinels of different dominant class, increasing personal vigilance when presented with subordinate surveillance calls compared to calls of a dominant groupmate in both noise treatments, suggesting complete masking was not occurring. However, a signal transmission experiment showed that surveillance calls were likely inaudible during periods of peak traffic, but audible during approaching traffic noise, thus reducing perceived call rate; in dwarf mongooses, lower surveillance-call rates are associated with higher risk situations, necessitating greater vigilance. While recent work has demonstrated detrimental effects of anthropogenic noise on defensive responses to actual predatory attacks, which are relatively rare, our results provide evidence of a potentially more widespread influence since animals should constantly assess background risk to optimise the foraging–vigilance trade-off.

    Research areas

  • anthropogenic noise, environmental change, vocal communication, predation, risk assessment, sentinel behaviour

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    Accepted author manuscript, 747 KB, PDF document

    Licence: CC BY-NC-ND


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