Intestinal bacteria play an important role in animal health. They extract and process nutrients present in their host's diet, help to develop their host's immune system, and recycle organic compounds, water, and minerals. The gut bacterial diversity is poorly known in wild animals. This study is the first description of the diversity of bacteria along the whole intestine of a wild bird (Passer domesticus). Pyrose-quencing of the 16S rRNA gene unveiled a high bacterial diversity, distributed in 11 bacterial phyla. The most abundant groups were Pro-teobacteria and Firmicutes. Bacterial diversity was greater in the upper section of the intestine and decreased toward the final portion of the gut. After a conservative denoising of the sequences, we found 4,436 OTUs in the gut of P. domesticus. Our data shows that the diversity of intestinal bacteria in the gut of wild birds is much larger than what had previously been estimated using fecal samples.