In Indonesia, it borders the the Australasian region. The big spider-shaped Sulawesi island is the center of of Wallacea, a transitional ecosystem between these, identified by both the WWF and Conservation International as a global conservation priority area. The name commemorates the naturalist Alfred Russel Wallace, who travelled through the region from 1854 to 1862, age 31 to 39, setting up bases on Makassar and Manado, to collect specimens for sale and to study natural history. He noted the differences in mammal and bird fauna between the islands either side of the now-called Wallace line. West of it, Sumatra, Java, Bali, and Borneo share a mammal fauna similar to that of East Asia, including tigers, rhinoceros, and apes, whereas those from Lombok and eastward are mostly populated by marsupials and birds similar to those in Australasia. Sulawesi shows signs of both.
The Indomalayan region is tropical, with exception of highlands, where the climate is colder.
|“||The tiger's roar filled the cave with thunder. Mother Wolf shook herself clear of the cubs and sprang forward, her eyes, like two green moons in the darkness, facing the blazing eyes of Shere Khan.||”|
—Rudyard Kipling, The Jungle Book
The Asian elephant (Elephas maximus) is the only elephant species which is regularly tamed, a cruel process which tourists are increasingly choosing not to support (see Chiang Mai#Wildlife for details). Fortunately, travelers can see Asian elephants in national parks and animal sanctuaries in several countries instead.
The Bengal tiger (Panthera tigris tigris) is the world's most numerous tiger species, and the national animal of India and Bangladesh. Other extant tiger populations include the Malayan tiger, the national animal of Malaysia that is also found in parts of southern Thailand, the Indochinese tiger found in parts of Thailand, Myanmar, Laos, Cambodia and Vietnam, and the Sumatran tiger found in Sumatra.
The leopard (Panthera pardus) was prevalent across the region, but is today endangered.
Asian pangolins are endangered and hard to see in the wild. African pangolins are healthier, ecologically speaking.
Orangutans are the only extant great apes native to Asia, or for that matter, to a region outside Africa. They are divided into three species: Sumatran (Pongo abelii), Tapanuli (Pongo tapanuliensis), and Bornean (Pongo pygmaeus). The former two can only be found in the wild on Sumatra, an island in Indonesia, while the later can only be found on Borneo, which is mainly split between Malaysia and Indonesia. All three species are critically endangered, making it extremely unlikely that you will encounter them in the wild.
The easiest way to see orangutans is to go to Sepilok Orangutan Rehabilitation Centre near Sandakan, Malaysia. They rescue Bornean orangutans that were illegally kept as pets or orphaned due to poaching, and attempt to rehabilitate them so they can be released into the wild. There are also numerous wildlife tours tours in the Malaysian state of Sabah, including along the Kinabatangan River and in the Danum Valley, where you will have opportunities to spot some. On the Indonesian side of the island, the tourism industry is not as well developed, though your best bet at seeing orangutans would be to go to Tanjung Puting National Park in Central Kalimantan.
The tourism industry is not as well-developed in Sumatra, making it harder to spot the Sumatran and Tapanuli orangutans, but Sumatran orangutan spotting tours are available from Bukit Lawang. The Tapanuli orangutan is the most endangered of all the great ape species, and found in the south and east of Lake Toba. As it was only discovered in 2017, it is not widely known yet, so as of 2020 there are no known tours to spot it.
The proboscis monkey (Nasalis larvatus) is a large monkey named for its exceptionally long nose. It lives only on the island of Borneo, and can be seen in all three countries (Malaysia, Indonesia, and Brunei) that divide the island. It generally lives in trees near water and is able to swim. It can be spotted easily from the rivers near Bandar Seri Begawan in Brunei and Bako National Park in Malaysia.
Macaques (Macaca) can be found in this region. Some kinds of macaques like to spend their time up in trees, whereas others are more likely to be seen on the ground. In areas with humans, you might see them trying to steal people's food. The most common macaque in Southeast Asia is the crab-eating macaque. The rhesus macaque is found in Hong Kong, southern China and the northern parts of South Asia and Southeast Asia. The Formosan rock macaque is unique to Taiwan, and the only non-human species of primate native to the island.
There are also numerous other monkey species that can be found in Southeast Asia. The silvery lutung is found in parts of Sumatra, Borneo and the Malay Peninsula; while the infants are born with pale skin and orange fur, their fur and skin colour eventually changes to grey by the time they reach sexual maturity. The banded surili is endemic to parts of Sumatra, southern Thailand, Peninsular Malaysia and Singapore.
The long-armed gibbon swings acrobatically through trees in most countries in Southeast Asia. The siamang is a type of gibbon native to Sumatra, Peninsular Malaysia and southern Thailand, and known for having a throat pouch that it uses to make loud, resonating calls.
The cute little slow loris is nocturnal and therefore hard to spot in the wild without some effort.
Pheasants (Phasianinae) are characteristic of south Asia.
The peafowl or peacock has two species in South Asia; the Indian Peafowl (Pavo cristatus) and the Green Peafowl (Pavo muticus).
The red junglefowl is the wild ancestor of domestic chickens, and is found in forested areas of eastern India, Bangladesh and Southeast Asia. While unable to fly long distances, they are generally better at flying than domestic chickens, and usually roost in trees.
Monitor lizards (Varanus) can be found in Indonesia and Malaysia. They are generally very big lizards, growing up to two meters or even more. Most live on land, but some can swim or climb trees. Though their size may be scary, they generally don't attack humans unless threatened and will probably waddle away (at a surprising speed!) when they hear you coming. The largest that still exist are Komodo dragons, which can grow up to three meters and can be seen in Komodo National Park in Indonesia, and those can attack people.
Banyan trees, also known as "strangler figs", are not unique to this part of Asia, but they're widespread here. These trees grow on other trees, and on walls, buildings, and bridges that have been abandoned for very long. They spread out in beautifully fascinating networks of branches, roots, and vines. Sometimes the original host rots away, leaving puzzling structures like hollow, right-angled, or perfectly cylindrical banyans, which give clues about what was there before these extraordinary trees took over. Some destinations (like the "Tree House" in Tainan) are famous for banyans, but you can find them on all kinds of historic structures, ruins, and ghost towns in the areas where they grow.
Osmanthus bushes produce small white flowers with a strong, sweet scent. The flowers are used to flavor food and drinks in China, including osmanthus wine.