And Pygmy Hippos spend far more time out of the water than their Nile Hippo counterparts, so if the second enclosure were merged with the Mandril enclosure, they wouldn't need to build another pool. At least not initially. If it were designed that they could be divided, then this would call for a third pool be built, but that could be a down the track renovation.
That’s a good point. It’s a shame to see the Mandrill exhibit has sat empty for so long (with the exception of Zillie’s stay). They should have moved the colobus to this exhibit a long time ago in my opinion; but presumably there’s a plan in place (quite possibly involving the Pygmy hippopotamus).
Due to holding a single bull for so long, I guess there’s been little justification for expanding his facilities beyond the two exhibits until now with the IRA finally approved (something which was never 100% guaranteed until it happened).