Why do bishops carry a shepherd's staff?

Roman Catholic AnswerCatholic bishops carry a crosier, which is an ornamental staff shaped like a shepher's crook. It symbolizes a bishop's role as caretaker of his flock. It may also be used by mitered abbots, and other privileged prelates.

from Modern Catholic Dictionary by John A. Hardon, S.J. Doubleday & Co., Inc. Garden City, NY 1980