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In the Lord of the Rings books, the Great Eagles are massive, intelligent and sentient birds who act as messengers for Manwë, the ruler of the Valar. Feathers are usually golden or bronze and they have piercing eyes. Their Talons are sharp enough to tear through flesh and metal. the feathers are usually golden or bronze with piercing eyes. They can understand and speak Quenya, Sindarin and Westron and form alliances with Elves, Men, and Dwarves when morally appropriate. Their moral alignment is always good, but they act wisely, not blindly, only intervening when necessary.
 
They travel fast and can see small objects from great distances. Unless slain in battle, they are immortal. They appear at key turning points, not as omnipresent heroes. They were sent to Middle-earth to help the free peoples and they play a crucial role by rescuing Gandalf, assisting in the final battle against Sauron and saving Frodo and Sam from Mount Doom at the end of the story. They are immortal spirits in bird form and act as agents of divine intervention, rescuing key figures at pivotal moments.
 
The Lord of the Eagles, Gwaihir, rescues Gandalf from the tower of Orthanc (Isengard) after he is imprisoned by Saruman. He later rescues Gandalf again from the peak of Mount Celebdil after searching for him at the request of Galadriel. At the end of The Lord of the Rings, the Eagles, led by Gwaihir the Windlord, Landroval son of Gwaihir and Meneldor, rescue Frodo and Sam from the slopes of Mount Doom after the One Ring is destroyed. While their role in the final rescue is crucial, Tolkien depicted them as a divine-like force that only intervened in extraordinary circumstances, rather than a readily available taxi service for Gandalf.

Bats were flying creatures of the night that tended to roost in caves or dark forests. Related to bats are also vampires, evil bat-like creatures. In the late First Age, Thuringwethil was Sauron's messenger and took the form of a giant bat with great fingered wings. Lúthien would take her form when she and Beren journeyed to Thangorodrim.​Bats were apparently quite common in the northern parts of Middle-earth. When Bilbo Baggins was walking alone in the tunnels of the Misty Mountains he heard the whirr of bats by his ears so often that it ceased to startle him. As Bilbo and the dwarves marched through Mirkwood they gave up lighting fires at night because they attracted thousands of moths, followed by huge black bats. Bats were most famous in Middle-earth for taking the part of the Goblinsduring the Battle of Five Armies, in which they flew together over the battlefield so densely that no light could be seen between their wings.

Crebain are large, crow-like birds from Dunland and Fangorn Forest that served as spies, most notably for Saruman. The Fellowship encountered a large flock of them in Hollin, which was seen as an ill omen and made the group hide without a fire, as they feared being spied on. The birds' intelligence allowed them to be used for reconnaissance, and their large numbers made them a significant threat. They flew in large, dark flocks and made a loud, croaking sound. While intelligent, they did not speak any language other than their own. Saruman, after he turned to evil, used them as spies. They were also associated with other evil powers and the Wild Men of Dunlending Hill Tribesmen.​​