The bronx Zoo uses the same sort of design in their outside "habitats". So you can look at a field-- with zebra in the foreground- and lions in the background-- and not see the "fence" that seperates them. From the Lion side, you see the wall is almost 10 feet high-- the lions "space" is almost like a little island--

Peacocks are allowed to roam free in the zoo-- and several years ago, one peacock's little pea brain-- didn't enlighten him to the purpose of the haha--

the haha in the tigers "cage" was enlarged after it was completed-- since the tigers, out of boredom, or maybe just because they were tempted by so much game, so close, where practicing "escaping" and came very close-- (and the "game" in question was a zoo keeper. )

But i don't remember the moat/embankment structure being called a haha at the zoo.