The Great Bustard ( Otis tarda ) and Common Crane ( Grus grus ) Utilize Food Resources via Gut Microbiota Remodeling During Wintering in the Yellow River Wetlands in Ordos City, Inner Mongolia, China

The great bustard ( Otis tarda ) and common crane ( Grus grus ), which are first‐ and second‐class protected animals in China, respectively, winter in the Yellow River wetlands of Inner Mongolia. The focus of this study was on the winter ecology of these birds in this region, in particular the relationship between their utilization of food resources and gut microbiota remodeling during the winter period. High‐throughput sequencing was used to analyze the diets and gut microbiotas of the birds, and liquid chromatography‐mass spectrometry was used to examine their fecal metabolites. The results showed that both bird species primarily consumed plant‐based food. The diet of the common crane consisted mainly of Poaceae plants, whereas that of the great bustard was relatively more diverse. The different diet components drove the diversity and composition of the gut microbiotas in the two species, with the great bustard exhibiting higher microbial diversity. The gut microbiota and metabolites of the common crane were mainly influenced by Poaceae plants, whereas those of the great bustard were influenced by multiple factors, with no single predominant driver. The gut microbiota of the great bustard contained more probiotic bacteria, whereas that of the common crane comprised a higher abundance of probiotic fungi. Moreover, the fecal metabolites of the great bustard were enriched with probiotic compounds such as flavonoids and phenolic acids, which are beneficial for overall health. This study provides insights into the survival status of these bird species, particularly the nationally protected great bustard, and offers a scientific basis for their conservation.