Communication and Social Behaviour Group, Max Planck Institute for Ornithology, 82319 Seewiesen, Germany.
Proc Biol Sci. 2013 Jan 8;280(1754):20122798. doi: 10.1098/rspb.2012.2798. Print 2013 Mar 7.
When animals live in cities, they have to adjust their behaviour and life histories to novel environments. Noise pollution puts a severe constraint on vocal communication by interfering with the detection of acoustic signals. Recent studies show that city birds sing higher-frequency songs than their conspecifics in non-urban habitats. This has been interpreted as an adaptation to counteract masking by traffic noise. However, this notion is debated, for the observed frequency shifts seem to be less efficient at mitigating noise than singing louder, and it has been suggested that city birds might use particularly high-frequency song elements because they can be produced at higher amplitudes. Here, we present the first phonetogram for a songbird, which shows that frequency and amplitude are strongly positively correlated in the common blackbird (Turdus merula), a successful urban colonizer. Moreover, city blackbirds preferentially sang higher-frequency elements that can be produced at higher intensities and, at the same time, happen to be less masked in low-frequency traffic noise.
当动物生活在城市中时，它们必须调整自己的行为和生活史以适应新的环境。噪声污染通过干扰声信号的检测，对声音通讯造成了严重的限制。最近的研究表明，与非城市栖息地的同类相比，城市鸟类会唱出更高频率的歌曲。这被解释为一种适应策略，以抵消交通噪声的掩蔽作用。然而，这种观点存在争议，因为观察到的频率转移似乎不如大声歌唱更能有效减轻噪声，并且有人提出，城市鸟类可能会使用特别高频率的歌曲元素，因为它们可以以更高的振幅产生。在这里，我们展示了首张鸣禽的语音图，该图显示在成功的城市殖民者普通乌鸫（Turdus merula）中，频率和幅度呈强烈正相关。此外，城市乌鸫更喜欢唱出可以以更高强度产生的更高频率的元素，并且同时在低频交通噪声中受到的掩蔽作用较小。
