They were certainly mentioned in a lot of recent marketing - so either they're coming later, there's been some problem/delay, they're not actually in Hidden Savannah but somewhere else, or they've simply been left off.
As I noted above, at least one enclosure label has been changed since they started showing labels in the app and the labelled species are hardly exhaustive in the rest of the map (only two of the four species are labelled for Monkey Islands, for instance) so I would be wary of taking any firm conclusions from the app.