array of waterfowl. Humboldt penguins are housed north of Bear Mountain. Former bird exhibits included: Bird Garden, an open-air mesh tent home to exotic birds including kookaburras, great argus and Cabot's tragopans. It was taken down on December 2, 2009, alongside enclosures for yaks, American bison, Mishmi takin, waterbuck, Ankole-Watusi cattle, muskoxen, Pallas' cats, mountain lions, reindeer and white-lipped deer, to make way for Toyota Elephant Passage. Bird World was open from 1975–2019. Its multiple exhibits were regarded as some of the best indoor tropical rainforests in the country. Tropical Discovery Tropical Discovery was opened in 1993 as the zoo's herpetarium and aquarium. The building explores several tropical environments and displays mammals, reptiles, fish, amphibians and insects from these areas. The trip begins with a view into a South American river with different species of river fishes then continues to a cave featuring several bat species including the short-tailed bat, Jamaican fruit bat and vampire bat, as well as blind cave fish. A snake exhibit hidden inside a Mayan temple features venomous species from around the world including the snouted cobra, eyelash viper and neotropical rattlesnakes. Animals seen in the Rainforest area include the capybara, Linne's two-toed sloth, archerfish and an array of poison dart frogs. Further on, visitors are immersed in a coral reef with false percula clownfish, lionfish, queen angelfish, spotted garden eels and more. Around the corner, a gallery of North American snakes is located across from the alligator snapping turtle and other North American reptiles and fish in a large pool. Further on, the Siamese crocodile also enjoys a large pool near the Matamata turtle and the Discovery Room, which features other small species like the frilled lizard. Dragons of Komodo was the largest Komodo dragon exhibit of its kind when it opened in 1999 and is still one of the largest Komodo dragon exhibits in the country. As well as housing Komodo dragons, Dragons of Komodo is home to other island reptiles like rhinoceros iguanas and giant New Caledonia geckos. Toyota Elephant Passage Toyota Elephant Passage is a $50 million exhibit. At its opening, it was the largest bull elephant habitat in the world, designed to house up to 12 elephants, 8 of them bulls. This arrangement allows the zoo to conduct behavioral research related to the recent discovery that bull elephants (originally thought to be solitary) form loose bachelor herds in the wild when