Comparative Analysis of Gut Bacteria of Four Waterbirds Species in Taolimiao-Alashan Nur (T-A Nur) in Erdos Relic Gull National Nature Reserve, Inner Mongolia, China.

Taolimiao-Alashan Nur (T-A Nur) is an important breeding site for the Relict Gulls () and many other waterbirds. To understand the gut health status of rare bird species living there and to protect these bird species, this study analyzed the gut microbiota of four waterbird species, including Relict Gull (), Black-necked Grebe (), Greylag Goose (), and Ruddy Shelduck (), using 16S rRNA high-throughput sequencing. Results showed that the gut microbiota of Ruddy Shelduck had the highest α-diversity, while Greylag Goose had the lowest. The composition of gut microbiota varied significantly among the bird species. The dominant bacterial phylum in the guts of Black-necked Grebe, Greylag Goose, and Ruddy Shelduck was Firmicutes, while it was Pseudomonadota in Relict Gull. At the genus level, the dominant bacteria were in Black-necked Grebe, in Relict Gull, in Greylag Goose, and in Ruddy Shelduck. Correlation analysis revealed significant relationships among gut bacterial communities, suggesting that gut bacteria can regulate host metabolism and physiological state by their interactions. KEGG functional predictions indicated that gut microbiota were primarily involved in metabolism. The abundance of metabolism-related microorganisms in Relict Gull was significantly lower than in Greylag Goose and Ruddy Shelduck, indicating that the gut microbiota of Greylag Goose and Ruddy Shelduck can provide stronger metabolic functions for the hosts. Additionally, microorganisms related to human diseases were more abundant in the gut of Relict Gull compared to Ruddy Shelduck and Black-necked Grebe, and in Greylag Goose compared to Ruddy Shelduck. These findings suggested that the gut microbiota of birds in this area harbor some human pathogens, which warrants attention and preventive measures.