Abstract <p>The results of a long-term study of the bird communities of Central Siberia, including route surveys 11 200 km in length in 685 biotopes, are summarized. It has been established that the population density of birds increases from the Arctic deserts to the southern tundra, significantly decreases in the forest tundra, and then sequentially increases to the forest steppe. The species richness also increases in the southern direction, but reaches its maximum in the middle taiga, where species with a more northern or southern distribution are located on the periphery of their ranges. The dominant composition of ornithocomplexes is characterized by the fact that one to four species are not spread beyond the boundaries of their own zones, and one to two species are common to neighboring zones. As a result of changes in the composition and ratio of species, the differences between the ornithocomplexes of the Arctic deserts and tundra, as well as between the forest–tundra and the taiga zones, become the most significant. Differences in bird communities of the forest tundra and tundra and of the forest-steppe and taiga zones are poorly pronounced due to the distribution of the most widespread species. Altitude-belt changes in the bird population consist of a sharp decrease in the number of species and individuals during the transition from each lower belt to the higher one. Bird communities of high-altitude belts are increasingly different from each other from the foothills to the peaks of the mountains and from communities of the adjacent lowland zones and subzones, which is determined by the increasing autonomy of their formation.</p>