Asian animals in U.S. zoos

Where two animal realms meet

Biogeographers split Asia between two realms. Temperate Asia is the eastern part of the Palearctic, shared with Europe, while the tropical south-east belongs to the Indomalayan realm. In southern Asia the boundary is largely a matter of altitude: the Himalayan foothills at about 2,000 to 2,500 m (6,600 to 8,200 ft) separate the two.

The continent blends animals of ancient northern and southern origin. India broke away from Gondwana about 90 million years ago and carried its animals north before colliding with Asia. Far to the south-east, the Wallace Line marks another sharp change: islands west of it share their animals with mainland Asia, while those to the east either lack land mammals or have fauna derived from Australia.

Mountains, forests and islands

Asia's mountains hold some of its most specialized animals. The snow leopard lives in alpine zones of 3,000 to 4,500 m (9,800 to 14,800 ft), with broad, furred paws for snow and loose rock. The red panda of the eastern Himalayas and south-western China is not related to the giant panda but shares its bamboo diet and a false thumb. The takin looks like a muskox, yet its closest relatives are sheep. The Himalayas alone contain about 8 percent of the world's bird species.

Tropical forests support one of the world's three principal primate communities, about 45 species, including lorises, tarsiers, langurs, gibbons and orangutans. The siamang, the largest gibbon, inflates a throat sac the size of its head to call. Treeshrews and colugos form two mammal orders found only in the Indomalayan realm. The northern tree shrew is one of the only mammals besides humans known to willingly eat spicy food. On a handful of Indonesian islands lives the Komodo dragon, the largest living lizard.

Under heavy pressure

Across Asia, poorly controlled industry and farming, dams, roads, poaching and timber theft are destroying wildlife habitats. Southeast Asia has the highest relative rate of deforestation of any major tropical region and could lose three-quarters of its original forests by 2100, along with up to 42 percent of its biodiversity.

The great apes show the cost. All three orangutan species are Critically Endangered, threatened by palm oil plantations, logging, poaching and the pet trade, and the siamang is losing rainforest to oil palm across Indonesia and Malaysia. Trapping matters as much as habitat: fewer than 50 Bali mynas were thought to survive in the wild by 2020, and the black market is estimated to move twice as many birds as are legally held in breeding programs.

A species that came back

Père David's deer shows what captive herds can do. Hunted out of the wild in China, it survived only through animals kept in Europe, and every living individual descends from a single breeding herd in England. Reintroduction to China began in 1985, and by 2020 a free-ranging population of about 2,825 deer roamed there. It is still listed as Extinct in the Wild until the reintroduced population proves it can last.