The correct expression is `waiting in the wings’. The `wings’ in this idiom has nothing to do with the wings of a bird. The idiom comes from the world of theatre. The word `wings’ refers to the sides of the stage, which are usually hidden from the audience by the curtain. Actors normally wait here before they walk onto the stage. When you say that someone is waiting in the wings, what you mean is that the person is ready to perform; all he needs is an opportunity.
*We must give him an opportunity. He’s been waiting in the wings for too long.