It's the outside off show area for the macaques. There are currently 6 males housed here, with access to offshow indoor area as well.
The actual babirusa enclosure is also an eyesore in my opinion. As can be seen in this photo the planting is sparse and the grass has not even grown. The fake waterfall looks ridiculous, and compared to other areas within Islands it looks like a desolate waste land! I'm very disappointed.