Codex on the Flight of Birds of a kite as seeking a wind current. When the winds are high, one will see the bird very high in the sky, but when the winds are low, the bird stays closer to the ground. Leonardo describes how a bird rests in the air, after flapping its wings to gain altitude, by gliding downward to the ground. Folio 6 contains multiple diagrams of birds flying and their bone structure, and all of the commentary is on flight and how birds fly the way that they do. Leonardo starts off by describing how a bird ascends or descends in different
Beak beak morphology. A number of species, including storks, some owls, frogmouths and the noisy miner, use bill clapping as a form of communication. Studies have shown that some birds use their beaks to rid themselves of excess heat. The toco toucan, which has the largest beak relative to the size of its body of any bird species, is capable of modifying the blood flow to its beak. This process allows the beak to work as a "transient thermal radiator", reportedly rivaling an elephant's ears in its ability to radiate body heat. Measurements of the bill sizes of several species of