Anthropogenic noise (≤ 3 kHz) can affect key features of birds’ acoustic communication via two different processes: (1) song‐learning, because songbirds need to hear themselves and other birds to crystallize their song, and (2) avoidance of song elements that overlap with anthropogenic noise. In this study we tested whether anthropogenic noise reduces the number of song elements in the repertoire of House Wren Troglodytes aedon, an urban species. Additionally, we tested whether the proportion of high‐frequency elements (i.e. elements where the minimum frequency is above 3 kHz) is related to anthropogenic noise levels, and how the frequencies and duration of shared elements between males change with different levels of anthropogenic noise. We recorded 29 House Wren males exposed to different anthropogenic noise levels (36.50–79.50 dB) during two consecutive breeding seasons from four locations. We recorded each male on 2 days during each season continuously for 50 min (we collected 104 h of recordings) and measured anthropogenic noise levels every 10 min inside each male territory during the recording period. In general, individuals inhabiting noisier territories had smaller repertoires. However, only in two locations with anthropogenic noise levels between 38.60 and 79.50 dB did males inhabiting noisier territories have smaller repertoires. In the other two locations with lower anthropogenic noise (36.50–66.50 dB), the anthropogenic noise inside each territory was not related to the repertoire size. Individuals inhabiting the noisiest location showed a tendency to include more high‐frequency elements in their songs. In 26% of the elements, the anthropogenic noise affected their frequency features. Our results showed that not all House Wrens inhabiting urban environments modify their songs at the highest level of organization (i.e. repertoire) to reduce the masking effect of anthropogenic noise on acoustic communication.

中文翻译：

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House Wrens Troglodytes aedon减少了曲目的大小，并响应人为噪声改变了歌曲元素的频率

人为噪声（≤3 kHz）可以通过两个不同的过程影响鸟类的声音交流的主要特征：（1）歌唱学习，因为歌鸟需要听自己和其他鸟的声音才能使它们的歌声结晶；（2）避免歌声元素与人为噪声重叠。在这项研究中，我们测试了人为噪声是否会减少House Wren Troglodytes aedon曲目中的歌曲元素数量，一种城市物种。此外，我们测试了高频元素（即最低频率高于3 kHz的元素）的比例是否与人为噪声水平有关，以及男性之间共享元素的频率和持续时间如何随人为噪声水平的变化而变化。我们记录了在四个地点连续两个繁殖季节中，有29只House Wren雄性在不同的人为噪声水平（36.50–79.50 dB）下暴露。我们在每个季节的2天中连续记录50分钟（收集了104小时的记录），并在记录期间每10分钟测量一次每个男性区域内的人为噪声水平。一般而言，居住在嘈杂地区的个人保留曲目较少。但是，只有两个地点的人为噪音水平在38.60到79之间。居住在嘈杂地区的男性的声音库较小，只有50 dB。在其他两个人为噪声较低的地方（36.50–66.50 dB），每个区域内的人为噪声与曲目集大小无关。居住在最嘈杂的地方的人表现出在歌曲中包含更多高频元素的趋势。在26％的元素中，人为噪声影响了它们的频率特征。我们的结果表明，并非所有居住在城市环境中的House Wrens都会在组织（即曲目）的最高级别上修改其歌曲，以减少人为噪声对声音传播的掩盖效应。每个区域内的人为噪声与曲目大小无关。居住在最嘈杂的地方的人表现出在歌曲中包含更多高频元素的趋势。在26％的元素中，人为噪声影响了它们的频率特征。我们的结果表明，并非所有居住在城市环境中的House Wrens都会在组织（即曲目）的最高级别上修改其歌曲，以减少人为噪声对声音传播的掩盖效应。每个区域内的人为噪声与曲目大小无关。居住在最嘈杂的地方的人表现出在歌曲中包含更多高频元素的趋势。在26％的元素中，人为噪声影响了它们的频率特征。我们的结果表明，并非所有居住在城市环境中的House Wrens都会在组织（即曲目）的最高级别上修改其歌曲，以减少人为噪声对声音传播的掩盖效应。