Columba livia landing by flapping with short steps

　If a gliding bird makes flap the wing back and forth, the lift will be increased. If a bird makes flap the wing up and down and then the angle of attack in the flapping up run changes to the same as that in the flapping down run, the thrust will be canceled out but the lift will be produced continuously. Farther, if the above flappings are combined the more large lift will be obtained. The small ratio of the outer blade to the inner blade in the primaries feathers and also the contacting sound accompanied with the flapping suggest that the cascade has been constructed and the feathers have been rotated. (Prod. Jun. 2005, full‐scale, No.1)