These huge Biomechanicle birds were designed by the Makuta to make a new and faster transport system. However, the Makuta's treachery lead them to take these animals under their command. Thus, these gentle giants unwittingly helped the Brotherhood take over the universe.
It definitely captrutes the old Rahi feel - the mask, the radical machine parts alongside animal ones. The only thing I think could be added to is the tail. Needs a blade on it. Can't have a decent rahi without at least 'one' blade on it. XD