The Great Eagles were the messengers and spies of the King of Arda who possessed the ability to see through most physical matter except for the deepest blackness of Morgoth's evil pits. They are possibly to be considered spirits of the Maiar who derived their abilities and shape from Manwë himself, but this is mere speculation. Morgoth first discovered the limits on their sight prior to the fall of the great stronghold of Utumno. Their leader and the king of these eagles was Thorondor and later descendents of his, which include the eagle lord Gwaihir, who carried Gandalf many times during the Third Age.

http://lotr.wikia.com/wiki/Great_Eagles

Спекулейшен-то спекулейшен, но Торондору в молодости удавалось разодрать морду целому Морготу. И они разумные, в отличие от "животных" Средиземья.

> все равно на орлах не долетишь, так ведь?

Я полагаю, там был вопрос совсем не в технической возможности долететь. Именно потому что орлы не простые.