I've long been disenchanted with the Smithsonian National Zoo. The zoo has suffered from horrible mismanagement, corruption, and political bullying since 2000. A major complaint of mine and everyone I've ever taken to the zoo in the last 10 years has been the severe lack of animals (including many major species) at such a major institution, especially since it used to have a world famous collection. Many animals were removed for Asia Trail and Elephant Trails and not replaced, even though many should've been accommodated in the new exhibit or elsewhere. In the last 10 years alone the zoo has displaced:
By Elephant Trails:
Masai and Reticulated Giraffes (didn't Jack Hana recently make a statement about what kind of zoo doesn't have giraffes? Well, National Zoo doesn't)
Indian Rhino (could've been accommodated in the new Asia exhibits)
Nile Hippo
Pygmy Hippo
Capybara
Andean Condor
By the giant panda expansion:
Bactrian Camel (could've been accommodated to the new Asia exhibits)
North American Bison (the zoo removed the bison from a brand new American prairie exhibit to build a 3rd queue area for the panda house, even though both entry areas to the panda house already had large queue areas.)
Red and Grey Kangaroos
A variety of Aussie Reptiles and Fish
And some of my favorite animals at the zoo:
New Guinea Singing Dog
Matschie's Tree Kangaroo
Short-Beaked Echidna (last I heard he was sent to the LA Zoo)
By the rest of Asia Trail:
Malayan Tapir (could've been accommodated to the new Asia exhibits)
Bongo
Reeve's Muntjac (could've been accommodated to the new Asia exhibits)
Sarus Crane (could've been accommodated to the new Asia exhibits)
Several varieties of Pond Turtles
A large variety of outdoor birds, including Pelicans, Swans, Geese, Storks, Ducks, Heron, Roadrunner, Quail, Partridge, Inca Tern, Golden Pheasant, and others, many of which could've been easily relocated or put on Asia Trail.
And a historic bald eagle cage that should've been renovated and not destroyed.
Other species throughout the zoo (some of these were displaced, others died off):
All of the zoo's Fruit Bats (2 species)
African Elephant
Bobcat
Serval
Leopard Cat
Johnston's Crocodile
Rhinoceros Iguana
Marabou Stork
Several varieties of Cranes
Kodiak Brown Bear
Dwarf Mongoose
Fennec Fox
Red Tailed and Harris Hawks
Red Wolves (though the zoo now does house Grey Wolves)
Grant's Gazelle
Lion-Tailed Macaque
Pygmy Marmoset
Bushbaby and Sugar Glider
Chinchilla
A variety of Fishes in Amazonia and Blind Cave Fish
And some more of my favorite animals:
White Tiger
Raggiana and Magnificent Birds of Paradise
Patagonian Mara
Again, all of those all disappeared in the last 10 years or so. Here are some other older ones in my memory:
African Leopard
Puma/Mountain Lion
Jaguarundi
Goliath Heron
Vietnamese Pot-Bellied Pig
Several varieties of Turkey
Several varieties of Deer
And many more species before my time (Black Rhino, Chimpanzee, etc.)
Currently the zoo is still on this destructive trend, with an upcoming renovation of the bird areas removing many more species (I'm not aware of which ones yet). The newly constructed Children's Farm was nearly torn down due to bad financial issues, nearly displacing the domesticated farm species. Also, a master plan proposal a few years ago wanted to rid the zoo of many of it's primates - with the Gorillas, Orangutans, Siamangs, White-Cheeked Gibbons, Sulawesi/Celebes Macaque, and Grey-Cheeked Mangabey being displaced to make room for a 3rd visitor center (Why does the zoo need 3 visitor centers? It already has functioning visitor centers/facilities at both ends of the zoo).
Frankly the zoo is a big disappointment for most people nowadays because it lacks so many many major animals (panda popularity only does so much) and has little remaining diversity. I sincerely hope the zoo reverses course and brings some of these species back soon, at least some of the main ones.