The scoop on eagles

[Gothmog]

This is a really old thread, but I have a question related to this topic but it's not important enough to start a new thread. So I'll just add this question to the ones above:

Why didn't the eagles drop the ring in... No, kidding. I'm not going to bring that one up... No, my question is this: in the 8th day after the fellowship left Lothlorien, Aragorn spots something in the sky and thinks it's an eagle. Legolas confirms that it is an eagle, a giant hunting-eagle. This makes them both worried and the following night they get attacked by orcs and for the first time the winged nazguls appear. What is the eagle doing there, far from it's normal habitat in the misty mountains? And is it more than a coincidence that the Nazgul appear the following night? The eagles are supposed to be almost neutral. Almost neutral as in not helping the good side too much but definitely not helping the dark side. Not interfering at all if possible. Is it possible that this eagle wasn't "neutral" and came to warn the fellowship? Or could it be an evil eagle?

Eagles are a symbol of Manwe and the good forces, so an eagle serving Sauron is quite unthinkable. But we now that he had other animals under control. Gandalf says something about many creatures serves him, both bird and beast. Is it possible to control noble beings like the eagles?

Unfortunately I don't have a copy of the books in English here right now so I can't provide any quotes. Quotes in swedish wouldn't help much I'm afraid...