There is a box on the magicians table which is made of three sections. Left and right sections are movable and the center one is fixed. The box size is exactly the size of one dove. The magician opens the box door and puts the dove in it. Then pushes the left section in to the center section. Now does the same thing with the right section, too. Two sections are now in the center one and the volume of this item is 1/3.

To show that the dove has vanished. there are 5 silver bars in the base and 5 holes on the center section (4 holes around the box and 1 center of the box) The magician puts all 5 bars through the holes then rotates the table to show spectators the end of all bars. After that, pulls out all bars from the holes and also the left and right sections of the box will be pulled out. The magician opens the box, the beautiful dove has returned, Unharmed!

Origami Dove Illusion (watch video)