Ueno Zoo, which was my local zoo, had these these species. So I thought they were pretty common in zoos. But after looking at information from a lot of zoos and Zootierliste, I now realize they are quite rare.
Chinese Pangolin
Spectral Tarsier
Lesser Mouse Deer
Aye-Aye
Galapagos Giant Tortoise
Komodo Dragon
Giant Panda
Okapi
Pygmy Hippopotamus
Indian Lion
It is good to be aware of the rarities in your local zoo(s) and not take them for granted because you regularly see them. If your local zoo was to go out of an uncommon species it might be a while before you see it again.