Seasonal Difference of Gut Microbiota at a Stopover Site in Five Passerines of Different Migratory Behavior.

Migration is a physically challenging period in a bird's life. Both seasonal variation and migratory behavior may shape the gut microbiota composition of migrating birds. In this study, we investigated the seasonal changes of gut microbiota in a total of 140 individuals across five passerine species with different migratory behaviors. 16S rRNA sequencing analysis revealed significant seasonal variation in the composition, except in the resident species Suthora webbiana. Species sharing similar migratory behaviors exhibited consistent seasonal patterns in their core gut microbiota. Notably, in migratory birds, we recorded lower body mass and a higher relative abundance of potentially pathogenic bacteria in spring than in autumn. Our results suggest that gut microbiota undergoes seasonal restructuring in response to the differing physiological demands associated with species-specific body condition, dietary, and migratory strategy, providing insights into host-microbe interactions across different passerines.