Full bird meter
After you beat the level after THE EVIL EYE. You must get through the last crystal flowers.Thats what I call them. When you see the green thing. There will be a fish .You will need to hold down the down button and press the B button and then you will see one or two sparkling thing fall down. When you get it your bird meter fully charge up.
Invincibility
Pause the game at any point and enter D,Y,L,A,D,B,R,C.
Level Select
Go to the OPTIONS screen.
Use the SECOND controller and press L,R,L,R,U,D,LS,RS,S.
The words SECRET MODE should appear at the top of the screen.
Now go back to the TITLE screen and press U,D,L,R,LS,RS,A,Y,C,Z,B,X.
You can now choose your starting level.
Replenish Life
Pause the game at any point and press ,RS,U,LS,X,A,Y,B,Z,C,R,L.
Now unpause the game for full life.
Secret Mode
Go to the OPTIONS SCREEN and on the 2nd controllerm press L,R,L,R,U,D,L,R,S.
You can now change your lives up to 99.
Self Kill
Pause the game at any point and press LS,A,RS,C,B.