Animals employing acoustic signals, such as birds, must effectively communicate over both background noise and potentially attenuating objects in the environment. To surmount these obstacles, animals evolve species-specific acoustic signals that do not overlap with sources of interference (such as songs of close relatives), and issue these songs from locations that maximize transmission. In multispecies assemblages of birds, the acoustic resource may thus be interspecifically partitioned along multiple axes, including song perch height and signal space. However, very few such studies have focused on open habitats, where differences in sound transmission patterns and limited availability of song perches may drive competition across multiple axes within signal space. Here, we demonstrate acoustic signal space partitioning in four sympatric species of wren-warbler (Cisticolidae, Prinia), in an Indian dry deciduous scrub-grassland habitat. We found that the breeding songs of the four species partition acoustic signal space, resulting in interspecific community organization. Within each species’ signal space, we uncovered different intraspecific patterns in note diversity. Two species partition intraspecific signal space into multiple note types, whereas the other two vary note repetition rate to different extents. Finally, we found that the four species also partition song perch heights, thus exhibiting acoustic niche separation along multiple axes. We hypothesize that divergent song perch heights may be driven by competition for higher singing perches or other ecological factors rather than signal propagation. Acoustic signal partitioning along multiple axes may therefore arise from a combination of diverse ecological processes.

中文翻译：

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Sympatric ren鸣鸟分隔声音信号空间和歌曲栖息高度

使用声音信号的动物（例如鸟类）必须通过背景噪声和可能衰减环境中的物体进行有效通信。为了克服这些障碍，动物会进化出与干扰源（例如近亲的歌曲）不重叠的特定于物种的声音信号，并从最大化传播的位置发出这些歌曲。因此，在鸟类的多物种组合中，声源可以沿多个轴进行种间分配，包括歌曲栖息高度和信号空间。但是，很少有这样的研究集中在开放的栖息地上，在这些地方，声音传播方式的差异和歌曲栖息地的可用性有限可能会推动信号空间内多个轴之间的竞争。这里，我们展示了印度干燥落叶灌丛草地生境中w鸣鸟（C科，普里尼亚）的四种同伴物种的声信号空间划分。我们发现，这四个物种的繁殖歌曲会划分声音信号空间，从而导致种间群落的组织。在每个物种的信号空间内，我们发现了音符多样性中的不同种内模式。两种将种内信号空间划分为多种音符类型，而另外两种将音符重复率不同程度地改变。最后，我们发现这四个物种还划分了歌鲈的高度，从而在多个轴上表现出声学利基分离。我们假设不同的歌曲栖息高度可能是由竞争更高的演唱栖息或其他生态因素而不是信号传播所驱动。