This may be cheating but oh well. At the Folsom City Zoo Sanctuary a black feral cat one day made it's way into Sequoia's, an American black bear, exhibit. Rather than eating the cat, the bear decided to become best friends with it. The two can now regularly be seen hanging it together. The zookeepers later nicknamed the cat "Little Bear." At the Folsom Zoo, a bear and cat enjoy each other’s company
Having watched black bears interact with wolves in Yellowstone Park on numerous occasions, I just can't see this being a stress-free environment for the animals. When I've seen them encounter each other in the wild, it's been a "high alert" situation for both species — unlike brown bear/wolf encounters, where the brown bears really don't seem to care.
I offer @Orycteropus's website, the zoorope.hu. If you click to Tartástechnológia, you can read English descriptions about mixed exhibits with bears and other carnivores.
Since I last posted in this thread I have also seen American black bears and brown bears mixed, at Pairi Daiza.
Animal Park Goldau built a bear-wolf exhibit: ZooLex Exhibit - Bear and Wolf But I echo Gary Robson's comment. If you read up on wolf and bear interaction, you soon learn that bears are known to kill wolves and wolf packs will attack bears. Some of this involves conflicts over kills but wolves apparently will hunt and kill black bears as prey. The Surprising Relationship Between Wolves & Bears And both bears and wolves are reported as killing and eating the other's young. I suppose keeping all of them well fed in a zoo and feeding them separately plus isolating any less than full grown animals from the mixed species exhibit could minimize the possibility of a conflict that could lead to injury or worse, especially if the wolf pack consisted of only a few animals, but I'd still consider it unacceptably risky.
Here's a very comprehensive report on mixed species exhibits with bears: en/Mixed exhibit Ursidae I am amazed at the number of zoos that have exhibited wolves and bears together, almost all in Europe.
Turtle Back Zoo keeps American Black Bears with Red Foxes. I only saw the Bears when I went in February, though.
A few zoos keep bears with foxes in the US it seems. California Living Museum had the same mix as above and Space Farms has Syrian Brown Bear with silver fox. ~Thylo
In a similar vein, Sequoia Park Zoo in Northern California exhibited an unreleasable pair of gray foxes with an elderly American black bear for several years successfully. It was a pretty small, old style grotto, but with renovations and lots of plantings the two species were generally able to get out of each other's way when desired. The mix only ended because the bear passed due to age, and the grotto is now home to a pair of bush dogs (to give an idea of how relatively small the space was).
NaturZoo Rheine has Sloth Bears with Golden Jackals, and had in the past a Golden Wolf (was back than still seen as a subspecies). Zoom Gelsenkirchen had Kamtschatka Brown Bears together with Artic Foxes.
