One of many bases, the Bird Base is best known for being used in the traditional crane; however, its appearance in many non-bird-related models is surprisingly frequent.
The paper here is 15cm x 15cm, single-sided origami paper. Any paper cut into the shape of a square should be usable.
Turn the paper over.
Fold the top down to meet the bottom edge. Crease then unfold.
Rotate the paper 90°.
Fold the top down to meet the bottom edge and crease.
Unfold.
Turn the paper over.
Bring the top left corner to the bottom right corner. Crease then unfold.
Bring the top right corner to the bottom left corner and crease.
Unfold.
Turn the paper over.
Rotate 45° so that a corner of the paper points towards you.
Bring the right corner to the bottom corner. Use the previous creases as a guide.
Bring the left corner to the bottom corner.
Bring the top corner down to meet the others.
Flatten the model. It should be in the shape of a square with the open side towards you.
Take the first flap of the bottom left side and bring its open edge to the vertical line in center.
Repeat on the other side using the bottom right side.
Fold the top triangle down over the other two flaps.
Unfold.
Open the topmost bottom flap.
Bring the bottom corner up.
Petal fold.
Turn the model over.
Fold the flaps in to the center.
Fold the top triangle down.
Petal fold. You have completed the Bird Base.