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：基于专家的鸟类物种栖息地特化种（habitat specialist）与栖息地泛化种（habitat generalist）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，采用三种不同方法量化其栖息地特化程度，并检验这些指标与物种丰度及栖息地关联的相关性。 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。基于上述数据，我们计算得到定量物种特化指数（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位当地鸟类专家组成的专家组，将每个物种划分为栖息地泛化种或栖息地特化种。 研究结果：经专家判定为栖息地特化种的物种，基于物种特化指数（SSI）以及基于典范对应分析（CCA）的栖息地生态位宽度，均表现出更高的栖息地特化程度；同时这些物种与某一主要栖息地类型的关联度也更强。在控制物种丰度的影响后，上述关联依然显著。 研究结论：由于专家分类结果与两种基于量化客观方法得到的物种栖息地特化程度指标相一致，本研究认为这些指标能够真实反映鸟类物种间栖息地需求广度的种间差异。鸟类栖息地特化程度的种间差异并非仅由物种间丰度的差异所导致。