The role of migratory birds in the long-distance dispersal of antibiotic resistance genes (ARGs) across ecosystems is of growing concern, yet the seasonal dynamics of the gut microbiome and resistome in migratory raptors—particularly large apex predators such as white-tailed sea eagles—remain critically understudied. To address this gap, we conducted a metagenomic study on the white-tailed sea eagle ( Haliaeetus albicilla ) at Jingxin Wetland, Northeast China, analyzing 29 fecal samples with comparable numbers across three distinct seasonal stages: 9 from southward migration, 10 from wintering, and 10 from northward migration. Our results revealed a distinct resistome profile characterized by 60 unique ARGs during the wintering period—accounting for 22.99% of the 261 genes detected—far exceeding those found during southward (4) and northward (9) migration.The gut microbiota was consistently dominated by Proteobacteria, Actinobacteriota, and Firmicutes (>70% total relative abundance), and Principal coordinate analysis (PCoA) revealed a significant separation of the wintering period from both migration periods in ARG composition (Adonis, P = 0.037), a pattern further supported by clear clustering in the corresponding heatmap. Our findings demonstrate that the wintering phase is a critical period for the accumulation and potential reorganization of ARGs in white-tailed sea eagles. This is likely driven by prolonged exposure to local environmental resistance pools at the stopover site, dietary shifts linked to aquatic food webs, and potential horizontal gene transfer within the gut. These findings establish white-tailed sea eagles as sentinel species for anthropogenic antimicrobial pressure in wetland ecosystems and identify wintering grounds as critical intervention nodes for mitigating ARG dispersal at the human–wildlife interface.
Zhang et al. (Mon,) studied this question.