I think they're generic hybrid baboons as the brochure just states they're "baboons" and has information on different baboon species.
Previous discussion of this subject (trying to find a link as we speak) reached the tentative conclusion that they are mostly Olive Baboons ('mostly' genetically speaking!) with some interbreeding with Yellow and possibly other baboon species. They seem to be predominately Olive though - I think the other species are pretty watered-down. EDIT: discussed (for reasons of perversity) in this Woburn thread: http://www.zoochat.com/38/woburn-14679/index8.html
