Host-Associated Differentiation of Gut Microbiota Among Four Crane Species Wintering in Rice Paddies Around Poyang Lake.

Whether different bird species retain distinct gut microbial communities when using the same broad foraging habitat remains unclear. We used 16S rRNA gene amplicon sequencing to characterize fecal microbiota from 51 samples representing four crane species wintering in rice paddies around Poyang Lake, China. The sampled species were Siberian cranes (Leucogeranus leucogeranus), white-naped cranes (Grus vipio), common cranes (G. grus), and hooded cranes (G. monacha). Taxonomic composition and all four alpha-diversity indices differed among host species, while beta diversity showed partial host-associated separation (PERMANOVA, R 2  = 0.19, p = 0.0033). Only eight of 124 core ASVs were shared across all four species, whereas 85 were species-specific. Common and hooded cranes clustered together in both host and microbial trees, providing limited topological concordance. However, host phylogenetic distance was not significantly associated with microbial community dissimilarity overall (Mantel r = -0.293, p = 0.667). Predicted functional profiles retained a substantial shared component, with 77.8% of KEGG orthologs detected in all four species, although overall functional composition differed significantly among hosts. Potentially pathogen-associated taxa occurred at generally low relative abundances and showed some variation among species. These findings show that shared use of rice paddies does not ensure microbial convergence and highlight the need to integrate dietary data when testing phylosymbiosis in wild birds.