Once that I know of. I'm not sure if one of the current pair is the chick that was hatched, about 6 or 7 years ago.
Originally they recieved six birds, I'm not sure where from but I think Edinburgh, in 1992.
IMO the humboldt mix was not conducive to breeding rockhoppers in that enclosure as the rockhoppers nest in the open, and humboldts are quite inquisitive. The exhibit was given an overhaul a few years ago, it may be that the rockwork provides areas now that only the rockhoppers can access, but that certainly wasn't the case before the refurb of the enclosure.
