@Arizona Docent The second section looks a little better, but I agree that the hornbill aviaries in the tropical hall look worse than some of the other aviaries. That said, I'm not sure live plants would work with hornbills.
@KevinB There are most definitely live trees in the hornbill aviary at my local zoo (I forget the species). Maybe it only works if the aviary is bigger?
@Arizona Docent That could well be the case, and perhaps indoor or outdoor versus indoor could also make a difference, not so much for the birds but for the resistance of plants.
@snowleopard Thank you for the examples. It does seem to me that the indoor examples you gave are both larger in size and better lit than the aviaries at Olmen.
That said, many of the aviaries on the second level of the tropical hall have been improved with additional perching and live plants, but the hornbill aviaries seem to be an exception, as well as the indoor parrot aviaries, where live plants probably wouldn't be an option, but where additional enrichment would be appropriate.
As I've said before, there have definitely been improvements at Olmen over the years, but there is still a lot of work left.