I imagine the Corby of the name is really a ‘Corbie’? – that is, as the OED says, a raven (or maybe a carrion crow).
That’s a nice image – the Corbies’ Crags.
But they’re not always ‘nice’ of course, as in this traditional Scottish ballad, The Twa Corbies, in which they daydream about picking out and eating the eyes of a dead knight:
books.google.co.uk/books?id=_g4JAAAAQAAJ&pg=RA1-PA283&lpg=RA1-PA283
Careful on those crags then.