Comparison of fecal microbiota of little egret (Egretta garzetta) inhabiting coastal and inland environments

The digestive tract of birds contains diverse microbiota that help hosts adapt to different environments. The environment is considered one of the main factors affecting the gut microbiota of wild animals, however, there is limited understanding of the role and function of environmental matrices in it. In this study, we collected feces of little egret ( Egretta garzetta ) from coastal saline and inland freshwater areas; analyzed the composition, diversity, and function of the microbial community using 16S rRNA high-throughput sequencing technology; and compared them with the soil and water microbiota to explore their interactions. We found that although the dominant bacterial phyla were the same, the dominant bacterial genera and the level II and III of the KEGG hierarchy of the microbiota of egrets in the two environments differed. We also observed that the egrets shared fewer core microbial communities with their living environment, and had significant differences in beta diversity. Overall, our results indicate that the microbial communities in the egret gut change with the bird's living environment; however, these changes showed a weak correlation with the water quality and soil of their habitats, suggesting that external environmental factors are not the main contributors to the gut microbiota differences. Since opportunistic pathogens were detected in the fecal microorganisms of the egret, especially individuals from the coastal saline area had a higher abundance of zoonotic pathogens such as Vibrio , research should be conducted to mitigate the ecological risk of intestinal pathogen transmission.