Spatio-species variation of halogenated organic pollutants reflected by bird feathers.

Feathers have emerged as a promising non-destructive monitoring tool for halogenated organic pollutants (HOPs). However, the influence of feather substructure and contaminant properties on HOP accumulation, and the ability of feathers to reflect regional and interspecific variation in contamination, remain incompletely understood. This study investigated HOP partitioning between feather shafts and vanes, evaluated the relationships between HOP concentrations and compositions in feathers and internal tissues, and examined spatial and species-specific variation across three representative regions in China. Perfluorosulfonic acids (PFSAs) preferentially accumulated in the shaft, whereas relatively short-chain perfluorocarboxylic acids (PFCAs, <C9), BDE 209, and p,p'-DDE were enriched in the vane. Whole feathers, rather than shafts or vanes alone, showed greater similarity to the PFAS profiles observed in bird internal tissues. PCBs, PBDEs, and DP concentrations were significantly higher in feathers from piscivorous birds at the e-waste site than in those from Poyang Lake and Yongxing Island. Significant interspecific differences in feather HOP profiles were observed. Piscivorous species associated with aquatic habitats showed greater contributions of PFOS, long-chain PFCAs, and lower-brominated PBDEs, whereas species with greater reliance on terrestrial food resources exhibited higher contributions of BDE 209 and short-chain PFCAs. These differences may be associated with variations in habitat use, dietary sources, and trophic position, although previous exposure history, particularly in migratory species, may also contribute. These findings highlight the importance of considering feather substructures and ecological traits in bird biomonitoring.