Abstract Birds living near airports can reduce the noise interference by advancing their dawn chorus timing and avoiding the start of airport operations. Data supporting this finding come from temperate areas, but little is known from tropical environments, where seasonal variation is lower and biodiversity is higher. Here, we investigated whether 15 tropical bird species are able to advance their dawn song and avoid aircraft noise interference. We sampled dawn song in three airports and three control sites in Brazil, using automated recording units. We found that dawn song times were not globally affected by the exposure to airport noise. Instead, changes were highly variable and species-specific, as dawn song onset was significantly advanced in two and delayed in four species. This large variation in responses was surprising given patterns found in previous studies. Indeed, this is the first time that a significant delay is reported for bird’s dawn song. We explored whether between-species differences in this response could be explained by additional variables (song frequency, degree of urbanity, and noise release), but none of them explained the direction or the strength of the changes. We suggest that earlier airport activity and shorter variations in day length and in twilight duration of tropical areas may be restricting birds’ ability to change dawn song timing. Further studies should consider these differences and analyze to what extent populational declines in noisy areas and the resultant reduced competition for acoustic space may be affecting the changes in dawn chorus onset time. Significance statement Birds have been shown to advance the timing of their song at dawn to avoid airport noise in Europe. However, we did not find a similar pattern in the birds near three Brazilian airport-affected sites, where the tropical environment can be a key factor (higher biodiversity and lower seasonal variation). We found that of the 15 studied species, only two followed this pattern, 9 species showed no changes in their timing, and 4 species showed the opposite trend, delaying their dawn song in an apparently non-adaptive manner. Neither differences in the birds’ song frequencies and degree of urbanity nor the noise release could account for delays in dawn song. We suggest that the birds’ ability to change their song timing may be limited by shorter seasonal light variations in tropical areas and by earlier airport activity in studied sites.

中文翻译：

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在热带机场附近鸟类种群的黎明歌唱时间中对飞机噪音缺乏一致的反应

摘要 居住在机场附近的鸟类可以通过提前黎明合唱时间和避免机场运营开始来减少噪声干扰。支持这一发现的数据来自温带地区，但对季节性变化较小且生物多样性较高的热带环境知之甚少。在这里，我们调查了 15 种热带鸟类是否能够推进它们的黎明歌唱并避免飞机噪音干扰。我们使用自动录音装置在巴西的三个机场和三个控制站点对黎明之歌进行采样。我们发现黎明歌曲时间并未受到机场噪音的影响。相反，变化是高度可变的并且具有物种特异性，因为黎明歌曲的开始在两个物种中显着提前，在四个物种中延迟。鉴于先前研究中发现的模式，这种反应的巨大变化令人惊讶。事实上，这是第一次有报道称鸟儿黎明的歌声出现了明显的延迟。我们探讨了这种反应的物种间差异是否可以用其他变量（歌曲频率、城市化程度和噪音释放）来解释，但没有一个解释了变化的方向或强度。我们认为，较早的机场活动以及热带地区白天长度和黄昏持续时间的较短变化可能会限制鸟类改变黎明鸣叫时间的能力。进一步的研究应考虑这些差异，并分析嘈杂地区人口下降的程度以及由此导致的声学空间竞争的减少，可能会影响黎明合唱开始时间的变化。重要声明 鸟类已被证明会在黎明时分提前鸣叫，以避免欧洲的机场噪音。然而，我们没有在三个受巴西机场影响的地点附近的鸟类中发现类似的模式，热带环境可能是一个关键因素（较高的生物多样性和较低的季节性变化）。我们发现在所研究的 15 个物种中，只有 2 个遵循这种模式，9 个物种的时间没有变化，4 个物种表现出相反的趋势，以明显不适应的方式延迟它们的黎明歌唱。鸟类鸣叫频率和城市化程度的差异以及噪音释放都不能解释黎明鸣叫的延迟。