The annual restrictions to protect nesting Ravens start on February 15th and run to 31st May while those to protect Peregrine Falcons start on 1st March and run to 30th June. There are a few crags with both Ravens and Peregines in residence, these are restricted from 15th February to 30th June.
Full details can be found in the Climbing area of this website and in The BMC’s Regional Access Database (RAD).