Yeah I might be wrong but I think that it’s only been this decade that they’ve even officially divided the zoo up into geographically-themed areas.Detroit Zoo doesn't seem too hung up on geography. In recent years they have kept fallow deer in both the eland and guanaco yards, and for a while had North American elk in the camel yard. Last time I visited a variety of birds from different continents were mixed in one of the big bird yards as well. That being said, plenty of zoos mix their pronghorn with bison, including relatively nearby Columbus, so that mix does make sense.