A Hunting Eagle???

[Leyrana Silumiel]

Hiya! I've been chugging along in my thorough re-reading of LOTR, and taking thorough notes for my thesis. I stumbled across a passage, and I'm not sure it holds any significance, but it would seem to me that it may.

There were many birds about the cliffs and the rock-chimneys, and all day high in the air flocks of birds had been circling, black against the pale sky. As they lay in their camp that day Aragorn watched the flights doubtfully, wondering if Gollum had been doing some mischief and the news of their voyage was now moving in the wilderness. Later as the sun was setting, the Company was stirring and getting ready to start again, he descried a dark spot against the fading light: a great bird high and far off, now wheeling, now flying on slowly southwards.

'What is that, Legolas?' he asked, pointing to the norther sky. 'Is it, as I think, an eagle?'

'Yes,' said Legolas. 'It is an eagle, a hunting eagle. I wonder what that forebodes. It is far from the mountains.'

I've checked for other references to this eagle, but I couldn't find one. I must have somehow missed this passage on every other reading of LOTR that I've done (or else then I didn't see the possible significance of it). Anyone have any clue what it could refer to or signify?