@Mr Gharial yes, they‘re hard to keep together, even in a huge aviary (for example Doue la Fontaine‘s Okapi sanctuary). The only way they can be mixed is keeping a green and a blue species, but there’s also a big chance that it won’t work.
Maybe this sign isn’t updated…
@Paul.Haerle I only saw 1 turaco and 1 hornbill in the aviary, so I think not updating the sign is the case. Which I understand. It´s very pretty sign. Great turaco is kept in Tropical Hall aviary, and white-bellied go-away-bird is kept in aviary nearby with rock hyrax, other birds, and tortoises. I don´t know where is the rest of the turacos.