Eagle Eagles are chordates where 60 different species exist. Flight muscles make up between 35 to 60 percent of the eagle's body weight. Eagles move by expanding and contracting muscles on their back, stomach, and wings which enables the wings to move up and down. They also have involuntary muscles that are attached to their feathers that help them to fly. When an eagle flaps its wings, most of the power for flying comes from the movement downward of the wings. For this reason, the muscles that pull the wings down are much larger than the muscles that pull the wings up. An eagle can fly faster or slower by changing the position of its wings. When It wants to fly fast, it turns the front edges of the wings into the wind and cuts through the air. When the eagle wants to slow itself down, it turns the wide surface of the wings into the wind, and the wings "drag" through the air. To slow themselves for a landing, eagles spread their wings and tall down, and drag them through the air to act like brakes.