Behavioral niche partitioning is an important and widely assumed mechanism for the coexistence of ecologically similar species. Here we assessed this mechanism by testing its core assumption, that evolved differences in foraging behavior correspond with differences in resources consumed. We combined data on foraging behavior, available prey, and observed diets of five coexisting species of New World wood warblers (Parulidae), a system that has been foundational to our understanding of behavioral niche partitioning. Consistent with past work, we found that the five species differed markedly in their foraging behavior, enough that some species pairs hardly overlapped at all in foraging microhabitat. In contrast, the birds overlapped highly in diet, while exhibiting small, interpretable differences in resource use. The high overlap resulted mostly from all five species consuming numerous ants, a prey source that moves between microhabitats. To test the prediction that the large differences in foraging behavior explain the small dietary differences, we generated expected diets based on available prey and foraging microhabitat use. Consistent with niche partitioning as a coexistence mechanism, we found that the small dietary differences were explained by a combination of foraging microhabitat and available prey, but this pattern was driven by only a small number of prey taxa. Thus, we found mixed support for behavioral niche partitioning. Our results indicate that foraging behavior among these bird species help explain subtle variation in diet, potentially facilitating coexistence. However, our results also revealed a weak relationship between foraging behavior and resource partitioning. Consequently, studies that rely solely on foraging behavior may greatly overestimate the degree of niche differentiation leading to erroneous conclusions. Overall, this study calls into question how and why these differences in foraging behavior evolved, and what role if any they play in facilitating coexistence.

中文翻译：

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重新审视行为生态位划分：行为差异是否可以预测莺的饮食差异？

行为生态位划分是生态相似物种共存的重要且广泛假设的机制。在这里，我们通过测试其核心假设来评估这种机制，即觅食行为的进化差异与消耗的资源差异相对应。我们结合了有关觅食行为、可用猎物和观察到的五种新世界林莺（Parulidae）共存物种的饮食的数据，该系统一直是我们理解行为生态位划分的基础。与过去的工作一致，我们发现这五个物种的觅食行为明显不同，足以使某些物种对在觅食微生境中几乎没有重叠。相比之下，这些鸟类在饮食方面高度重叠，同时在资源利用方面表现出小的、可解释的差异。高度重叠主要是由于所有五个物种都食用大量蚂蚁，这是一种在微生境之间移动的猎物来源。为了测试觅食行为的巨大差异解释了饮食的小差异的预测，我们根据可用的猎物和觅食微栖息地的使用生成了预期的饮食。与生态位划分作为共存机制一致，我们发现微小的饮食差异可以通过觅食微栖息地和可用猎物的组合来解释，但这种模式仅由少数猎物类群驱动。因此，我们发现了对行为利基划分的混合支持。我们的结果表明，这些鸟类的觅食行为有助于解释饮食的细微变化，可能促进共存。然而，我们的结果还揭示了觅食行为和资源分配之间的弱关系。因此，仅依赖觅食行为的研究可能会大大高估生态位分化的程度，从而导致错误的结论。总体而言，这项研究质疑这些觅食行为的差异是如何以及为何演变的，以及它们在促进共存方面发挥的作用（如果有的话）。