Glaucous gull going by force against strong wind

　To go against wind, the bird's speed must be faster than that of wind. Then, the thrust is taken precedence than the lift. It is important to reduce the drag, too. As the methods increasing the thrust, we can consider the raise up of the amplitude and frequency of the flapping, the change of the angle of attack in the flapping down and up runs, the beating of the wing parallel to the stream, and the enlarged flapping down angle. The flapping with the downward concaved wing may be adequate to take the above methods totally. Thick feathers covering up the body form the thickest spindle-shape with the short neck. It may protect the durable muscles and the internal organs, and also prevents the stream separation and reduces the frictional drag together with the drawn in legs and a little curved wing. There are the possibilities in which the surface effect in the bottom of the atmosheric boundary layer and the effect of the increased density in snow-air two phase flow are used. (Prod. Sep. 2005, scale 1/2, No.1)