House swallow in bounding flight by riding on wind over sea wave

　It is said that the swallows migrate by tiny group or sometims separately in skimming close to sea surface. It may be convenient to protect a foreign enemy, and to make use of the ascending and acceleratin wind blowing over the sea waves, and also to make use of the surface effect. If the ascending and accelerating wind near the top of sea waves is utilized to the beating accelerating run in the intermittently beating flight, the economical flight may be possible on the force burden and the energy consumption. Anyway it is surprised to imigrate between Japan and Southeast Asia with the weight of only 18 gram. (Prod. Aug. 2006, full-scale, No.1)