Animals glean information about risk from their habitat. The acoustic environment is one such source of information, and is an important, yet understudied ecological axis. Although anthropogenic noise has become recently ubiquitous, risk mitigation behaviors have likely been shaped by natural noise over millennia. Listening animals have been shown to increase vigilance and decrease foraging in both natural and anthropogenic noise. However, direct comparisons could be informative to conservation and understanding evolutionary drivers of behavior in noise. Here, we used 27 song sparrows (Melospiza melodia) and 148 laboratory behavioral trials to assess foraging and vigilance behavior in both anthropogenic and natural noise sources. Using five acoustic environments (playbacks of roadway traffic, a whitewater river, a whitewater river shifted upwards in frequency, a river with the amplitude modulation of roadway traffic, and an ambient control), we attempt to parse out the acoustic characteristics that make a foraging habitat risky. We found that sparrows increased vigilance or decreased foraging in 4 of 6 behaviors when foraging in higher sound levels regardless of the noise source or variation in frequency and amplitude modulation. These responses may help explain previously reported declines in abundance of song sparrows exposed to playback of intense river noise. Our results imply that natural soundscapes have likely shaped behavior long before anthropogenic noise, and that high sound levels negatively affect the foraging-vigilance trade-off in most intense acoustic environments. Given the ever-increasing footprint of noise pollution, these results imply potential negative consequences for bird populations.

中文翻译：

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自然和人为的噪音提高了松雀的警觉性并减少了觅食行为

动物从栖息地收集有关风险的信息。声学环境就是这样一种信息来源，是一个重要但尚未被充分研究的生态轴。尽管人为噪声最近变得无处不在，但数千年来自然噪声可能已经塑造了风险缓解行为。倾听动物已被证明可以提高警惕性并减少自然和人为噪音中的觅食。然而，直接比较可以为保护和理解噪声行为的进化驱动因素提供信息。在这里，我们使用 27 只歌雀 (Melospiza melodia) 和 148 个实验室行为试验来评估人为和自然噪声源中的觅食和警觉行为。使用五种声学环境（道路交通、激流河、一条白水河的频率向上移动，一条具有道路交通幅度调制的河流，以及一个环境控制），我们试图解析出使觅食栖息地有风险的声学特征。我们发现麻雀在较高声级觅食时，在 6 种行为中的 4 种行为中提高了警惕性或减少了觅食，无论噪声源或频率和幅度调制的变化如何。这些反应可能有助于解释先前报道的暴露于强烈河流噪音播放的歌麻雀数量下降的原因。我们的研究结果表明，自然声景可能早在人为噪声之前就已经塑造了行为，并且在最强烈的声学环境中，高声级会对觅食-警惕性的权衡产生负面影响。鉴于噪音污染的足迹不断增加，