Low-frequency urban noise can interfere with avian communication through masking. Some species are able to shift the frequency of their vocalizations upwards in noisy conditions, which may reduce the effects of masking. However, results from playback studies investigating whether or not such vocal changes improve audibility in noisy conditions are not clear; the responses of free-ranging individuals to shifted signals are potentially confounded by functional trade-offs between masking-related audibility and frequency-dependent signal quality. Black-capped chickadees (Poecile atricapillus) naturally sing their songs at several different frequencies as they pitch-shift to match conspecifics during song-matching contests. They are also known to switch to higher song frequencies in response to experimental noise exposure. Each male produces both high- and low-frequency songs and absolute frequency is not a signal of aggression or dominance, making this an interesting species in which to test whether higher-frequency songs are more audible than lower-frequency songs in noisy conditions. We conducted playback studies across southern and central British Columbia, Canada, using paired song stimuli (high- vs low-frequency songs, n = 24 pairs) embedded in synthetic background noise created to match typical urban sound profiles. Over the course of each playback, the signal-to-noise ratio of the song stimuli was gradually increased by raising the amplitude of the song stimuli while maintaining background noise at a constant amplitude. We evaluated variation in how quickly and aggressively territorial males reacted to each of the paired stimuli. We found that males responded more quickly to playbacks of high- than low-frequency songs when high-frequency songs were presented first, but not when low-frequency songs were first. This difference may be explained by high-frequency songs being more audible combined with a carry-over effect resulting in slower responses to the second stimulus due to habituation. We observed no difference in overall aggression between stimuli. These results suggest that high-frequency songs may be more audible under noisy conditions.

译文

低频城市噪声会通过掩蔽干扰鸟类通信。某些物种能够在嘈杂的条件下向上移动发声的频率,这可能会减少掩蔽的影响。然而,来自回放研究的结果尚不清楚这种声音变化是否会改善嘈杂条件下的可听性; 自由放送的个体对移位信号的响应可能会因与掩蔽相关的可听性和频率相关的信号质量之间的功能权衡而混淆。黑帽山雀 (Poecile atricatillus) 自然会以几种不同的频率唱歌,因为它们会在歌曲匹配比赛中进行音高转换以匹配特定对象。众所周知,它们会响应实验噪声暴露而切换到更高的歌曲频率。每个雄性都会产生高频和低频歌曲,而绝对频率并不是攻击或支配的信号,这使其成为一个有趣的物种,可以在嘈杂的条件下测试高频歌曲是否比低频歌曲更容易听到。我们在加拿大不列颠哥伦比亚省南部和中部进行了播放研究,使用了嵌入合成背景噪声中的成对歌曲刺激 (高频和低频歌曲,n = 24对),以匹配典型的城市声音配置文件。在每次播放过程中,通过提高歌曲刺激的幅度,同时将背景噪声保持在恒定幅度,逐渐增加歌曲刺激的信噪比。我们评估了领土雄性对每个配对刺激的反应速度和积极程度的变化。我们发现,当首先呈现高频歌曲时,男性对高频歌曲的播放反应比低频歌曲的反应更快,而在低频歌曲首次出现时则没有反应。这种差异可以通过高频歌曲的可听性更高,并结合了遗留效应来解释,该效应由于习惯而导致对第二刺激的响应较慢。我们观察到刺激之间的总体攻击没有差异。这些结果表明,在嘈杂的条件下,高频歌曲可能更容易听到。

+1
+2
100研值 100研值 ¥99课程
检索文献一次
下载文献一次

去下载>

成功解锁2个技能,为你点赞

《SCI写作十大必备语法》
解决你的SCI语法难题!

技能熟练度+1

视频课《玩转文献检索》
让你成为检索达人!

恭喜完成新手挑战

手机微信扫一扫,添加好友领取

免费领《Endnote文献管理工具+教程》

微信扫码, 免费领取

手机登录

获取验证码
登录