The giant otters went on show for the first time on 26 March 2010. The zoo bred their first pups in 2013. In the neighbouring enclosure, a large breeding group of over 50 Humboldt penguins have their own pool, and visitors can watch the birds from an underwater viewing window. Tropical Realm Chester's Tropical Realm is Britain's largest tropical house at over 26,000 cubic metres. Opened in 1964, most of the interior is an open-plan space extending to roof level and themed with pools and mature tropical plants, with pathways for visitors through the undergrowth. Here, more than 30 species of birds are free-flying, including Nicobar pigeons, various species of starlings and ground birds such as crested partridges. Aviaries and vivaria are arranged around the sides of the building; those on the upper level were originally designed for birds-of-paradise and the hornbill aviaries were originally made for gorillas. The aviaries currently house birds like Sunda wrinkled hornbills,rhinoceros hornbills, two pairs of tarictic hornbill (one pure-bred and one hybrid), writhed-billed hornbills, schalow's turacos, Palawan peacock-pheasants, Congo peafowl, Bali starlings, blue-crowned pigeons, fairy-bluebirds, white-rumped shama, white-crested turacos, snowy-crowned robin-chats, Mindanao bleeding-hearts green aracari and Luzon scops owls. At the entrance is an aviary for Sumatran Laughingthrush. The Tropical Realm is also the centre of the reptile collection. The crocodile pools (which formerly housed West African dwarf crocodiles, American alligators and Philippine crocodiles) currently house spectacled caimans in one and white-winged wood ducks in another . Near the entrance is an enclosure for tuataras. This lizard-like species from New Zealand is the last surviving sphenodont, a prehistoric group of reptiles, and Chester is the only British zoo to exhibit them. In February 2016, a tuatara hatched for the first time outside of New Zealand, leading Chester Zoo to be the only zoo to have bred them anywhere else. There were many varieties of snakes and lizards in the past (many had to depart as a result); emerald tree boas now being the only remaining. The lizard collection is now made up of Serrated casquehead iguanas, Graham's anoles, caiman lizards, and a Parson's chameleon. Tortoises are represented by radiated. Amphibians include poison dart frogs, golden mantellas, a Rio Cauca caecilian, Borneo eared frogs and Morelet's tree frogs. There is also a pair of Philippine mouse-deer near the poison dart frogs. In the winter of 2015/2016 the former yellow breasted capuchin exhibit at the rear