Interactions between diet and gut microbiota and differentiated metabolic adaptations in sympatric migratory birds during autumn migration preparation at high altitudes

To investigate food resource utilization and gut microbiota metabolic adaptation in sympatric migratory birds during autumn migration preparation at high altitudes (> 4,500 m), we studied Grus nigricollis , Tadorna ferruginea , and Anser indicus in the Yellow River Source Area of Sanjiangyuan National Park. Fecal DNA metabarcoding, 16S rRNA sequencing, Spearman correlation, and MetaCyc/KEGG pathway analyses revealed distinct interspecific differences in diet, gut microbiota, and metabolic functions. G. nigricollis preferred starch-rich Argentina anserina tubers and chitin-rich Tipula subcunctans , whereas T. ferruginea mainly consumed fiber-rich Stuckenia pectinata together with diverse animal foods, and A. indicus exhibited intermediate dietary diversity. The gut microbiota of G. nigricollis was dominated by lactic acid bacteria that fermented starch into short-chain fatty acids, promoting energy storage, while T. ferruginea was enriched in cellulolytic bacteria that converted fiber into energy. Although A. indicus exhibited the highest microbial diversity, no significant diet–microbiota correlation was detected. Functionally, G. nigricollis enhanced both catabolic and anabolic pathways for efficient fat accumulation, T. ferruginea primarily enriched anabolic pathways to support dietary diversity, and A. indicus optimized energy metabolism to maintain homeostasis. These findings provide new insights into microbial mechanisms underlying migratory energetics and inform wetland food resource management.