Gwaihir the Windlord is never explicitly connected with the Eyrie of the Misty Mountains, but the association is strongly suggested by the fact that he and his fellow Eagles were said to be 'of the North' (The Return of the King VI 4, The Field of Cormallen). This is not absolutely conclusive, because there were evidently many different eyries in the North of Middle-earth (at the Battle of Five Armies, the Eagles '...must have gathered from all the eyries of the North', according to The Hobbit 17, The Clouds Burst). Nonetheless, the main Eyrie of the Misty Mountains was home to the Lord of Eagles at the time of Quest of Erebor, so it seems natural to assume a connection to the Windlord Gwaihir, quite possibly a Lord of Eagles himself.