How and how did the birds adapt to different environmental conditions?

The birds have adapted to a wide variety of environmental conditions. Most of them conquer the air, which helps:
1) a special structure of feathers with barbs and barbs, clinging to each other and creating a flying surface;
2) the fusion of many bones in the skeleton, including the formation of a buckle and ankle, which makes it possible to withstand enormous loads during flight;
3) significant development of the cerebellum and vision.
For birds that have mastered the aquatic habitat, the presence of a special air cushion, which is formed by the lower layer of feathers, is characteristic, as well as the enhanced work of the glands (including the coccygeal), which makes the feathers non-wettable. Running birds have highly reduced wings and a closed pelvis for cushioning running movements.