Kern Julie M, Radford Andrew N
School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, University of Bristol, BS8 1TQ, United Kingdom.
Environ Pollut. 2016 Nov;218:988-995. doi: 10.1016/j.envpol.2016.08.049. Epub 2016 Aug 29.
Anthropogenic noise is rapidly becoming a 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 exhibited a lessened response to surveillance calls in traffic-noise compared to ambient-sound playback, increasing 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 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 dominance 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, an acoustic-transmission experiment showed that while surveillance calls were potentially audible during approaching traffic noise, they were probably inaudible during peak traffic intensity noise. 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.
人为噪声正迅速成为一种普遍的环境特征。虽然这种额外噪声对鸟类性信号的影响已有充分记录，但我们对其在其他陆地生物分类群中、对其他发声以及对接收者的影响的了解更为有限。例如，尽管存在潜在的适应性后果，但关于人为噪声对与捕食风险相关的发声反应的影响却知之甚少。我们通过回放实验来研究交通噪声对觅食的侏獴（Helogale parvula）对哨兵发出的警戒叫声的反应的影响，哨兵是从高处扫描危险的个体，其存在通常会导致觅食者的警惕性降低。与在环境声音回放中相比，觅食者在交通噪声中对警戒叫声的反应减弱，从而提高了自身的警惕性。第二个回放实验，使用没有警戒叫声的噪声回放，表明这种增加的警惕性可能部分源于额外噪声的直接影响，因为仅对交通噪声回放的反应就有所增加。声学掩蔽也可能起作用。觅食者保持了区分不同优势等级哨兵的能力，在两种噪声处理中，与优势同伴的叫声相比，当听到从属哨兵的警戒叫声时，它们会提高自身的警惕性，这表明完全掩蔽并未发生。然而，一项声学传播实验表明，虽然在接近的交通噪声期间警戒叫声可能听得见，但在交通高峰强度噪声期间它们可能听不见。虽然最近的研究表明人为噪声对实际捕食攻击的防御反应有不利影响，而实际捕食攻击相对较少见，但我们的结果提供了证据，表明其影响可能更广泛，因为动物应该不断评估背景风险以优化觅食 - 警惕性之间的权衡。
