The intestinal microbes are huge and diverse microbial communities, which play key roles in maintaining organism health through promoting nutrient uptake, defense, and immune regulation. However, any change in the intrinsic and extrinsic factors can affect the composition of gut microbiota, especially the food composition. The feeding habits of birds vary wildly, from fruit, seeds, foliage to carrion and capturing live animals. Bird life-history traits are diverse, such as migratory behavior, flight capacity, diet, mating systems, longevity and physiology, all of which may affect gut microbes. With the development of gene sequencing technology, and the increasing attention to intestinal microbes, intestinal bacterial diversity of birds has received some attention. However, publications are dominated by the studies of domestic poultry. The structure changes and maintenance mechanism, and the influencing factors of gut microbes in wild birds remain less studied. Here, we review current knowledge of the intestinal microbes in wild birds, to better understand the dynamics of wild bird gut microbiota, and will contribute to the future study of avian microbiology. In general, among the wild birds with different feeding habits, herbivorous birds have the lowest intestinal bacterial diversity, with high abundance of Proteobacteria and Firmicutes; and omnivorous birds have the highest intestines bacterial diversity. Genetics, life-history, human activities, urbanization, captive behaviors, etc. have significant effects on the bacterial diversity of wilds bird gut microbes.