Great egret in typical beating flight with two hinges

　It is known that the great egret uses the two joints for the beating and there is a phase gap between the motion of the primaries and the secondaries. That is the flapping up run of the secondaries begins in the midst of the flapping down run of the primaries. It may produce the lift and the thrust continuously. When it flaps up the secondaries, it makes large the angle of attack to keep the lift. The resultant negative thrust may be canceled out by the positive thrust produced by the flapping down of the primaries (by the bending of the wrist). The neck of the great egret is long. Thereby, the egret is used to bend the neck to S-type at the flying.
(Prod. Jan. 2003, scale 1/2, No.1)