This statement is a metaphor for saving ones self from a bad situation. It is derived from a bird in free-fall. If the bird spreads its wings, it can simply soar and stop it's impending pain/demise. Likewise, when a bird wants to fly away quickly, it spreads its wings wide open and with a few powerful thrusts flies away. Consequently, this statement is often used to remind one of their inner strength.

When you eat dirt for the first time and leave your family to build a shack in the woods