Studies of intraspecific dietary variation can greatly enrich our view of a species’ niche and role in the ecosystem, particularly when species with broad diets are found to be composed of generalist and specialist individuals. However, the current framework for quantifying dietary specialization leaves certain standards unformalized and is susceptible to overestimating specialization when there are few repeated observations per individual, as is often the case in observational studies of wild populations. Here, we use the hihi (Notiomystis cincta), a threatened New Zealand passerine, as a case study for demonstrating how existing statistical tools can be applied to strengthen the dietary specialization framework. First, we assess whether the reliability of common dietary measures can be improved through Bayesian adjustments and by using rarefaction to compare uncertainty levels of metrics calculated from different sample sizes. As diet links closely to environmental factors, we also demonstrate how adding phenological data and habitat assessments to standard protocols can help validate our dietary measures as evidence for resource selection rather than random foraging. Finally, in light of our finding that diet predicts survival in hihi, we discuss the utility of dietary specialization for elucidating broader behavioral syndromes.

中文翻译：

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在野生动物种群的观察研究中加强饮食专业化指标

种内饮食变化的研究可以极大地丰富我们对物种的生态位和在生态系统中的作用的看法，尤其是当发现具有广泛饮食的物种由通才和专业人士组成时。但是，当前量化饮食专业化的框架使得某些标准尚未正式化，并且当每个人重复观察的次数很少时，容易受到高估专业化的影响，这在野生种群的观察研究中经常如此。在这里，我们使用hihi（Notiomystis cincta），这是一个受到威胁的新西兰雀形目，作为一个案例研究来说明如何使用现有的统计工具来加强饮食专业化框架。首先，我们评估是否可以通过贝叶斯调整和使用稀疏度比较从不同样本量计算出的指标的不确定性水平来提高常规饮食措施的可靠性。由于饮食与环境因素密切相关，因此我们还演示了如何将物候数据和生境评估添加到标准方案中，可以如何帮助验证我们的饮食措施作为资源选择而不是随机觅食的证据。最后，根据我们的发现饮食可以预测hihi的存活，我们讨论了饮食专门化在阐明更广泛的行为综合症方面的作用。