Data from: Habitat specialization of birds in the Czech Republic: comparison of objective measures with expert opinion

CAPSULE: Expert-based classification of bird species as habitat specialists and as generalists agrees with objective measures of species’ habitat requirements based on large-scale monitoring data. AIMS: To compare habitat specialization of 137 common bird species breeding in the Czech Republic using three different measures and to test their relationships to species’ abundance and habitat associations. METHODS: Data on bird abundance and surveyed habitats were collected through a standardized monitoring scheme of common breeding species in the Czech Republic. From these data we calculated a quantitative species specialization index (SSI). Canonical correspondence analysis (CCA) was applied to calculate species’ habitat niche breadth and the level of association of each species to the main habitats. A panel of 11 local bird experts classified each species as habitat generalist or habitat
specialist. RESULTS: Species classified as habitat specialists by expert opinion showed higher habitat specialization according to the SSI, as well as according to CCA-based habitat niche breadth. These species were also
more closely associated with one of the main habitat types. These relationships were significant even
after controlling for abundance. CONCLUSIONS: As expert opinion accords with the level of species’ habitat specialization expressed using two quantitative objective measures, we suggest that these characteristics reflect real interspecific variation in the breadth of habitat requirements in birds. Interspecific differences in habitat specialization are not
caused solely by the variability in abundance among species.

研究概要：基于专家经验将鸟类物种划分为栖息地专性物种与广适性物种的分类结果，与基于大规模监测数据得到的物种栖息地需求客观度量结果相一致。
研究目标：针对在捷克共和国繁殖的137种常见鸟类，采用三种不同度量方式对比其栖息地特化程度，并检验这些度量与物种丰度及栖息地关联之间的关系。
研究方法：通过针对捷克共和国常见繁殖鸟类的标准化监测方案，收集鸟类丰度与调查栖息地相关数据。基于这些数据，我们计算得到量化的物种特化指数（Species Specialization Index, SSI）。采用典范对应分析（Canonical Correspondence Analysis, CCA）计算物种的栖息地生态位宽度，以及各物种与主要栖息地类型的关联程度。由11位本地鸟类专家组成的专家组，将每个物种划分为栖息地广适种或栖息地专性种。
研究结果：经专家经验划分为栖息地专性种的物种，基于SSI的栖息地特化程度更高，同时基于CCA得到的栖息地生态位宽度指标也显示出更高的特化程度。此类物种与某一类主要栖息地类型的关联更为紧密。即便在控制物种丰度的影响后，上述关联仍具有统计学显著性。
研究结论：由于专家经验分类结果与通过两种量化客观度量得到的物种栖息地特化程度相一致，因此我们认为这些特征能够反映鸟类物种间栖息地需求广度的真实种间差异。鸟类栖息地特化程度的种间差异并非仅由物种间丰度的变异所导致。