Chaoyang Wang ¹ Chao Zhang ¹ Hao Cai ¹ Yunlong Zhu ² Jiwan Sun ³ Wen Liu ³ Zhenyu Wang ^1* Yankuo Li ^1*

• ¹ College of Life Sciences, Jiangxi Normal University, Nanchang, Jiangxi Province, China
• ² State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
• ³ Office of Poyang Lake Water Control Project Construction of Jiangxi Province,, Nanchang, China

Extreme weather events driven by climate change profoundly affect migratory birds by altering their habitats, food sources, and migration routes. While gut microbiota is believed to play a role in helping birds adapt to environmental changes, research on how extreme weather impacts their gut microbiota and how these microbial communities respond to such conditions has been limited. In this study, we utilized 16S rRNA gene sequencing to investigate the gut microbiota of common cranes (Grus grus) wintering at Poyang Lake from 2020 to 2023, with a particular focus on their response to extreme drought conditions on both inter-annual and monthly timescales. Our findings revealed that extreme drought conditions substantially impact gut microbiota, with inter-annual water-level fluctuations exerting a more pronounced impact on microbial community structure than that of inter-monthly fluctuations. Notably, a significant decline in bacterial diversity within the gut microbiota of common cranes was observed in the extreme drought year of 2022 compared with other years. Monthly observations indicated a gradual increase in gut microbial diversity, coinciding with relatively minor water-level changes. Key taxa that responded to drought included the Enterobacteriaceae family and Bifidobacterium and Lactobacillus species. Additionally, functional genes related to carbohydrate metabolism, the phosphotransferase system, and the two-component systems were significantly enriched during the extreme drought year. These functions may represent adaptive mechanisms by which the gut microbiota of common cranes respond to drought stress. This research provides novel insights into the temporal variability of gut microbiota in wintering waterbirds, underscoring the significant impact of climatic fluctuations on microbial communities. The findings highlight the importance of understanding the ecological and functional responses of gut microbiota to extreme weather events, which is crucial for the conservation and management of migratory bird populations in the face of climate change.