The Outlaws of Sherwood by Robin McKinley
Tales of the Sherwood Forrest, the women and men who rob of the rich and give to the poor. They train to shoot their arrows straight and true.
They try to keep on the good side of the sheriff as they want no duel with him.
They take on plans to rob from Roger as he's stolen things from Little John and Roger wants to steal a woman away from one that is betrothed.
The contest of the golden arrow attracts many to the event.
The outlaws continue to do good but not all see it as such.
They use whistles in the forest to communicate with everybody.