Abstract
The wild populations of red-crowned cranes (Grus japonensis) in west China are gradually decreasing, necessitating the optimization of reintroduction measures. This study used 16S rRNA high-throughput sequencing technology to compare the gut microbiota communities of cranes living in two modes (captive and semi-free-range) before their reintroduction in Zhalong National Nature Reserve, Heilongjiang Province, China. The results showed that Proteobacteria (74.39%) and Firmicutes (25.29%) were the dominant gut bacterial phyla inhabiting these cranes. Significant differences were found in the gut microbiota community composition between semi-free-range and captive cranes (p < 0.01). Psychrobacter, Sporosarcina, and Lactococcus were significantly enriched in captive cranes (p < 0.05), while Pseudomonadaceae_Pseudomonas, Pantoea, Lysobacter, and Enterobacteriaceae_Pseudomonas were more abundant in semi-free-range cranes (p < 0.05). The functions and community structure of gut microbiota were affected by feeding patterns (p < 0.05). The metabolic pathways of ethylbenzene degradation, PPAR signaling pathway, betalain biosynthesis, systemic lupus erythematosus, and shigellosis were up-regulated in semi-free-range cranes (p < 0.05).