There seems to be a bird of prey nesting on buttress 4 in the Rocky Valley at Ilkley. I think could be a peregrine but i'm not well up on my ornithology. Anyway I would suggest avoiding climbing on buttress 3 and buttress 4 until the chicks fledge in June or so.
I saw it while walking along the path at the bottom - it seemed to be going in and out of a hole in one of the offwidths.
Post edited at 13:54