Spy-birds

Birds in the service of Saruman, capable of spying out the movements of his enemies and reporting to their master. The term is especially associated with the black crows known as crebain, though other kinds may have existed. It is uncertain how these spy-birds reported what they had discovered to Saruman; they must have had some means of communicating, but whether they were able to speak is unclear (we know that the ravens of Ravenhill had this ability, so it is not entirely implausible).

Saruman's ability to use birds as spies and lookouts was one that he shared with at least one of his fellow Wizards. Indeed, he may have learned the skill from Radagast, who was especially skilled in communication with birds and used them himself to watch the Enemy and carry news.