Leonardo's study of the motion of the air was closely linked to his studies on water. On several occasions he states that an understanding of the movements of swimming fish is essential for grasping the principles of the flight of birds.

In his maturity, Leonardo's investigations were focused on observing the way in which birds exploit winds and air currents. From this research came pioneer knowledge on the operation of winds and currents, on the anatomical conformation of birds, and on the versatility of their adaptation to the forces of air.