Temporal changes in the gut microbiota of overwintering great bustard Otis tarda dybowskii

Abstract

The gut microbiota of wild birds is sensitive to external environmental factors. Under the stress of cold temperatures in winter, seed-eating birds residing in stable habitats for a prolonged period experience gradual deterioration of dietary resources as time progresses. Investigating the dynamics of the gut microbiota of endangered birds throughout the wintering phase can offer an essential foundation for designing specific conservation measures. In this study, fresh faecal samples were collected from populations of great bustard Otis tarda dybowskii in stable wintering habitats during early, mid, and late winter. The gut microbiota of the great bustard at different time points was comparatively analyzed using high-throughput sequencing of the 16S rRNA gene. The results showed that the gut microbiota of overwintering great bustard comprised primarily 4 phyla: Firmicutes (80.13%), Bacteroidetes (10.54%), Actinobacteria (6.86%), and Proteobacteria (1.23%), accounting for 98.75% of the total microbial abundance across all samples. While there were no significant differences in the gut microbiota during the early and mid-winter periods, significant changes occurred during the late wintering period. There was a significant decline in cofactor and vitamin metabolism, along with lower bacterial richness indices. In the late wintering period, the great bustard population in the wild may face increased survival pressures. Providing food supplementation before spring migration could potentially play a crucial role in saving this endangered species.