The otters have only been on exhibit for about 5 weeks, but now they will be gone for most of the summer behind-the-scenes as the zoo recently found out that pups were born. While at the zoo yesterday some visitors were quite disappointed as there has been a lot of promotion in regards to the new Bamboo Forest Reserve zone, but I'm sure that the same people will come back to tour the zoo once the babies are on display.
No, it is actually built in a brand-new area. There are 3 ancient grottoes at the zoo and two of them can still be seen (African Lions and Sloth Bears) while the third one (empty - used to be Sun Bears) is no longer possible to view. That trio will be combined to form a large Malayan Tiger/Sloth Bear complex that will open in 2015. The Sloth Bear grotto was closed down to the public for several months and it was only re-opened recently when the twin cubs went on display.
The new Asian Small-Clawed Otter exhibit, along with the Asian aviary and children's play zone, just opened last month and all 3 areas do not really use anything that was existing before. The end section of a Butterfly Forest zone (seasonal) that was around for just over a decade is where the Bamboo Forest Reserve phase one zone is, and the main visitor pathway has been shifted slightly northwards.