Foraging Environment Shapes the Gut Microbiota of Two Crane Species in the Yellow River Delta Wetland

The foraging environment is a critical source of microbes for wild birds, yet its role in shaping the gut microbiota of sympatric crane species remains poorly understood. This study investigated this relationship in the Yellow River Delta wetland by analyzing the microbial communities of paired foraging environments and fecal samples from Common Cranes (Grus grus) and White Cranes (Grus leucogeranus) via 16S rRNA gene sequencing. Significant inter-group differences in alpha diversity (ACE, Chao1, Shannon, Simpson) indicated strong environmental filtering effects. Beta diversity (PCoA) revealed pronounced segregation between foraging and fecal samples (PC1 = 25.0%), underscoring a significant microbial turnover between the environment and the gut. Dominant phyla included Proteobacteria (24.6–37.4%), Firmicutes (4.8–29.0%), and Actinobacteriota (12.4–23.3%). LEfSe identified genus-level biomarkers highly specific to sample type and host, including Ligilactobacillus (12.1% in Common Crane feces) and Cryobacterium (9.2% in White Crane feces). SourceTracker analysis indicated that >70% of gut microbial sources remained unknown, suggesting a vast uncharacterized environmental reservoir. Functional prediction highlighted group-specific adaptations, such as elevated amino acid transport metabolism in Common Cranes (9.8% vs. 7.1%; p < 0.05), potentially linked to local dietary resources. Our findings demonstrate that the gut microbiota of cranes is synergistically shaped by host-specific factors and the unique saline–alkaline foraging environment of the wetland.