DISSERTATION RESEARCH: The Acoustic Niche and Decline of Avian Diversity

人类是非常嘈杂的，我们发出的声音在音调上是不同的，而且往往比大多数自然环境中听到的声音大得多。环保人士担心，由人类产生的噪音主导的新声学背景可能会对许多鸟类产生负面影响，即因为它们严重依赖声音交流，噪音可能会掩盖或淹没它们的歌声和叫声，使它们在功能上保持沉默。这可能是特别有问题的，因为鸟类发声的声学特征受到物种的限制？进化历史和身体大小到特定的频率范围和幅度限制。换句话说，物种有声学上的小生境，可能无法调整发声来在我们这个嘈杂的世界中进行有效的交流。然而，最近一些鸟类被证明在它们的声学生态位上有一些灵活性，并调整它们的发声来克服噪音的掩蔽效应。在这个项目中，研究人员的目标是1)确定声学生态位灵活性在鸟类群落中是常见的还是罕见的，以及2)评估一个物种？占据嘈杂栖息地的能力取决于声学生态位的灵活性。为了实现这些目标，研究人员将把他们的研究重点放在10种已知对噪音的耐受性有显著差异的物种上：4种避免嘈杂的栖息地，2种喜欢嘈杂的栖息地，以及4种似乎不受噪音影响的物种。对于每个物种，研究人员将记录和测量许多个体在噪音强度梯度内唱歌或叫声的发声特征。由于该项目是一个社区范围的方法，结果将加强对鸟类物种中声学生态位灵活性普遍性的有限了解。这在人类改变的景观及其周围的鸟类保护方面尤其重要，因为它将提供必要的洞察，了解为什么许多物种放弃了嘈杂的地区，为什么少数物种可能会繁衍生息。

Humans are extremely noisy and sounds that we produce are different in pitch and often much louder than sounds heard in most natural settings. Conservationists have worried that the new acoustic background dominated by human-generated noise may negatively affect many birds, namely because they rely heavily on vocal communication and noise may mask or drown-out their songs and calls, rendering them functionally silent. This may be especially problematic because acoustic characteristics of bird vocalizations are constrained by a species? evolutionary history and body size to specific frequency ranges and amplitude limits. In other words, species have acoustic niches and may unable to adjust vocalizations to effectively communicate in our noisy world. Recently, however, a few birds have been shown to have some flexibility in their acoustic niche and adjust their vocalizations to overcome the masking effects of noise. In this project, the investigators aim to 1) determine whether acoustic niche flexibility is common or rare within an avian community and 2) evaluate whether a species? ability to occupy noisy habitat is dependent on acoustic niche flexibility. To achieve these objectives the investigators will focus their research on ten species known to vary markedly in their tolerance to noise: four species that avoid noisy habitat, two species that prefer noisy habitat, and four species that appear uninfluenced by noise. For each species, the investigators will record and measure vocalization characteristics from many individuals singing or calling throughout a noisy intensity gradient. Because the project is a community-wide approach, results will enhance the limited understanding of the universality of acoustic niche flexible among bird species. This is especially important in terms of avian conservation in and around human-altered landscapes because it will provide needed insight as to why many species abandon noisy areas and why a handful may flourish.