@lintworm It is indeed quite impressive, the aviary is very tall and extensive and is big enough that once you're inside you don't feel like you're in an aviary, it's just that if you look up you see netting. The KL Bird Park claims they have the world's biggest free-flight aviary.
I think it's impressiveness is fairly illusionary; the species kept are fairly 'meh' and overall the whole park feels like someone somewhere doesn't really care.
The largest aviary claim has been repeatedly stated on ZC to be a reference to the total enclosed space at the bird park, rather than any single exhibit. Having said that I'm not sure I've seen any evidence either way. It certainly doesn't feel like it.
I agree with FG that the species kept free-flying aviary are all rather uninteresting. It's mostly large waterbirds and other common large species: storks, herons, egrets, crowned-pigeons, etc. There are interesting and unusual species at the KL Bird Park, but they're all in separate aviaries. The lack of free-flying small birds of anything much smaller than an oriole is disappointing.
However I still found the size of the big free-flight areas impressive. Of course it's much easier to create large tropical free-flight aviaries in the tropics because you don't need to heat anything, and the bird park is located in a botanic gardens and it feels like they've just netted over a bit of the gardens.
