The bears left the mappins around 1984-85, I think the polar bears went to dudley, they also still had brown and black bears until then but I don't know where they were sent. I don't think any other bear species were on the mappins past the late 70s. I first saw them in 1985, after the bears had left, and there were brown pelicans in the bottom pool, wild boar and collared peccaries in the pig pens, and barbary sheep/mouflon/markhor/ bighorn on the mountains. I believe the mouflon were loaned to a farm park in somerset, I've no idea where anything else went.
Bear mountain was opened I think in 1997, that's when I first saw it.
I think gibbons were tried on the mappins briefly at one point, these were the lar gibbons moved from the long cage under the trees by three island pond, not the golden-cheeked/hybrid pair, I never saw them but remember an email with the news story. It obviously didn't work as they were soon gone.
Visually the exhibit is now very impressive, although I wouldn't like to be up there with all that sand on a windy day! Structurally, the terraces were never designed to have tonnes of earth dumped on them, maybe that's also why the change has happened?