Most of the creases in a stretched bird base are present in the regular bird base. When forming this bird base, make sure to crease the triangle at the center corner through all layers. (If you unfold completely, you will see a small square at the center of the paper.) After forming the bird base, either partially unfold the paper, and/or "stretch" two opposite corners of the bird base. These two corners, their associated flaps, and the central square will all lie flat. The other two flaps will form a pyramid. Rabbit ear each flap that is in the pyramid, so that the model lies flat. All of the raw edges will lie along the centerline of the model. The stretched bird base is used in Lang's Bald Eagle, Greenberg's Eeyore, and some other high-intermediate and complex models.