The tail - is very important for flight and maneuvering. While the bald eagle is soaring or gliding in flight, the tail feathers are spread, in order to attain the largest surface area and increase the effect of thermals and updrafts. The tail also helps to brake the eagle when landing and assists in stabilization during a controlled dive or swoop toward prey. The strength of the feathers and the follicles holding the feathers is quite impressive, while watching the tail move back and forth and up and down during maneuvers. Bald eagles have 7,000 feathers.
Eagle feathers are lightweight yet extremely strong, hollow yet highly flexible.
They protect the bird from the cold as well as the heat of the sun, by trapping layers of air. To maintain its body temperature an eagle simply changes the position of its feathers. While an eagle suns itself on a cold morning, it ruffles and rotates its feathers so that the air pockets are either opened to the air or drawn together to reduce the insulating effect. Feathers also provide waterproofing and protection, and are crucial for flight. Feather structure makes pliability possible.