Crebain flock in the New Line film
The Crebain were a wicked species of crow-like birds who spied for Saruman. They spied on the Fellowship of the Ring when they tried to pass through Dunland, causing the Fellowship to hide. They hid for the entire day as flocks of Crebain continued to fly by, seeking information about the Ring of Power. They rushed to tell Saruman what they had seen, and that the Fellowship had to take the dangerous path through Moria. Before the Battle for Helm's Deep, the Crebain spied on the Rohirrim and reported to Saruman that they heard word of Saruman's plan to destroy them.