@Fossa dude - I haven't been to Denver Zoo, so I don't know the layout or how much space is available, but I'm sure at the very least they should have some space off-display where they could construct an aviary.
Those are shockingly poor and cramped enclosures to exhibit Parrots in! Wild Keas fly big distances in their mountain habitat, yet here the single(?) bird is being housed rather like an inactive reptile in a tank. For the Cockatoo(s) things look no better.
So many American zoos are described as 'worldclass' with enormously lavish and expensive exhibits, yet the USA gallery also shows the 'other side of the coin' with exhibits such as this and one or two of the terrible 'indoor only' fishtank-style Orangutan enclosures at other Zoos that have also been featured.
If ever I saw an advert for what is bad about Zoos, this would be one.
I know this doesn't make the cage any better but usually there is a mess of puzzles and toys. It's pretty cool to see the bird put the right color of chip in the right color of container.
In the wild in New Zealand's South Island, Kea live in flocks high up on scree slopes of the Mountains. They are curious, inquisitive birds, more so even than most other Parrots. They also fly at high elevation, travelling high above valleys and mountain passes and have large territories. How different from living in a small glass box like this. Unlucky Keas.