I was so focused on the bird exhibits that I didn't give the mammal exhibits equal time. Plus, I had only four hours to see the zoo, and that wasn't nearly enough time. For some reason, I didn't expect that Mandrill could be mixed with other primates (it's probably because of the size of their canine teeth!). I'm glad to hear that it's working out in San Diego!
@Summer Tanager Mandrills, Drills and most of the Afro-Eurasian monkeys kept in AZA are able to be mixed together, especially if the sexual ratio incudes mostly females in at least one of the species.
@Grant Thank you - I had no idea! I've seen guenons and colobus mixed at several zoos, and it's common to see mixes of lemurs, as well as mixes of tamarins, marmosets, sakis, and titis, but mixes involving Mandrills, mangabeys, and macaques seem to be rare (or I'm not paying close attention). I appreciate you adding this comment!