Were the serval and fennec enclosures the only mock rock enclosures on the edges of the aviary? I recall there being a third one for the hyraxes before they were placed on the island.
In this photo - African Wetland - ZooChat - the Fennec cage is behind me and the Serval cage is at the far end, but there is a "staff only" structure in between which potentially may also have formerly been an enclosure.
@Chlidonias if I recall correctly there used to be a smoking area in the park (which could be seen from the map from 2016 I posted) before the park went smoke free. If you are on the side of the aviary that’s by the tropical forest exhibit, then the box should be the smoking box.