Summary of seabird assemblages.

Dominant species were defined as those summing to ≥ 50% of species’ relative density for each assemblage. No dominant or co-dominant species are listed for the singles assemblage (Fig 4), as five species were needed to meet the ≥ 50% relative density threshold. Mean relative density relates to all cell-days within an assemblage. The silhouette coefficient assessed each cluster’s distinctness or ‘goodness’ where 1 indicates ideal clustering, 0 indicates that observations are between two clusters (cluster is not highly distinct), and -1 indicates observations are in the wrong cluster. Cell-day = a single 10 x 10 km cell with seabird observations in a given day.

优势种（dominant species）的定义为：在任一物种集合中，相对密度之和≥50%的物种。单一种群集合未列出优势种或共优种（co-dominant species）（见图4），因需纳入5个物种方可达到≥50%的相对密度阈值。平均相对密度对应某一物种集合内的全部单元格-日（cell-day）样本。轮廓系数（silhouette coefficient）用于评估各聚类簇的区分度与“聚类质量”：取值为1时代表理想聚类，取值为0时代表观测样本介于两个聚类簇之间（聚类簇区分度较低），取值为-1时代表观测样本被错误分配至聚类簇。单元格-日（cell-day）指某一日内存在海鸟观测记录的单个10×10 km网格单元。