Like the others said it was to symbolize his freedom.He was the caged bird.Besides that oro specifically said he wants nothing to do with this war.So why would he then turn around and go to ground zero ?
That eagle was to symbolize Neji's freedom. It was shown during the Chuunin exam arc as well.
There was a chapter called bird in a cage, when naruto faught neji, I think its as metaphorical message for neji being free from his curse realising it in his dying moments
hmmmm....that hawk maybe