The fauna of Indonesia consists of a high level of biodiversity due to its vast-size and tropical archipelago make-up. Indonesia divides into two ecological regions; western Indonesia is more influenced by Asian fauna, and the east is more influenced by Australasian. The Wallace Line—in fact, more an area known as Wallacea—notionally divides these two regions. This unique blend of fauna in Indonesia is also affected by the diverse range of ecosystems, including beaches, sand dunes, estuaries, mangroves, coral reefs, sea grass beds, coastal mudflats, tidal flats, algal beds, and small island ecosystems.
Ecological issues have appeared in the nation due to the rapid industrialisation process and high population growth, resulting in lower priority level to preserve the ecosystems. The situation has worsened by illegal logging activity, in which resulting deforestation; while other problems, including high level of urbanisation, air pollution, garbage management and waste water services also contributing to the forest deterioration.
Origin of Indonesian fauna
The origin of fauna in Indonesia is heavily affected by geographical and geological events on the Asian continental landmass and the Australasian continental landmass (now Australia). The present New Guinea island was connected with the present Australia continent, forming a supercontinent called the southern supercontinent Gondwana. This supercontinent began to break up 140 million years ago, and the New Guinea region (previously known as Sahul) moved towards the equator. As a result, animals from New Guinea traveled to the Australian continent and vice versa, creating many different species living in different ecosystems. This activities continued to occur until the two regions separated completely.
The influence of the Asian continental landmass, on the other hand, was the result of the reformation of the Laurasia supercontinent, which existed after the breakup of Rodinia around 1 billion years ago. Around 200 million years ago, the Laurasia supercontinent split completely, forming Laurentia (now America) and Eurasia continents. The mainland of the Eurasia continent, including China, was not separated completely from the Indonesian archipelago. As a result, animals from the Eurasia mainland could travel to the archipelago, and, under a different ecosystems, new forms of species were formed.
In the nineteenth century, Alfred Russel Wallace proposed the idea of the Wallace Line, a notional line dividing the Indonesian archipelago into two regions, the Asian zoogeographical region (Sundaland) and the Australasian zoogeographical region (Wallacea). The line runs through the Malay Archipelago, between Borneo and Sulawesi (Celebes); and between Bali and Lombok. Although the distance from Bali to Lombok is relatively short, only about 35 kilometres, the fauna distribution is still affected by the line. For example, a group of birds would refuse to cross even the smallest stretches of open water. A second line, lying east, known as the Webber Line, has also been proposed to separate between "transition species" and species of Australian origin.
This includes Sumatra, Java, Borneo and the smaller surrounding islands, share similar characteristics with Asian fauna. During the ice age, after the Laurasia break up, the main Asian continent was connected with the Indonesian archipelago. Moreover, a low sea level enabled animals from the Asian mainland to migrate to Sundaland. As a result, large species such as tiger, rhinoceros, orangutan, elephant, and leopard exist in this region, although some species are categorised as endangered species. The Makassar Strait, between Borneo and Sulawesi, and the Lombok Strait, between Bali and Lombok, which is the Wallace Line separator, mark the end of the Sundaland region.
Sundaland has a total of 381 mammal species. 173 of them are endemic to this region. Most of these species are currently endangered. Two species of orangutans, Pongo pygmaeus (Borneo orangutans) and Pongo abelii (Sumatran orangutans ) are listed in the IUCN red list. Other famous mammals, such as the Borneo proboscis monkey (Nasalis larvatus), the Sumatran rhinoceros (Dicerorhinus sumatrensis) and the Javan rhinoceros (Rhinoceros sondaicus) are also seriously threatened.
According to the Conservation International, a total of 771 bird species occur regularly in Sundaland. 146 of them are endemic to this region. Java and Bali have at least 20 endemic species, including the Bali starling (Leucopsar rothschildi) and the Javan plover (Charadrius javanicus).
Reptiles and Amphibians
An astonishing 449 species in 125 genera of reptiles are estimated to live in Sundaland. 249 species of them and 24 genera are endemic. Three reptile families are also endemic to this region: Anomochilidae, Xenophidiidae and Lanthanotidae, the last represented by the Bornean earless monitor (Lanthanotus borneensis), a very rare and little-known lizard. Around 242 species of amphibians in 41 genera live in this region. 172 species of them, including the Caecilian and six genera are endemic.
Nearly 200 new species are discovered in the last ten years in this region. Around 1000 species of fishes are known to live in the rivers, lakes, and swamps of Sundaland. Borneo has about 430 species, with 164 of them considered endemic. Sumatra has 270 species, 42 of which are endemic. The well-known golden arowana (Scleropages formosus) is one of the best examples for the fishes of this region.
The Wallacea represents the biogeographical transitional zone between the Sundaland to the west and the Australasian zone to the east. This zone covers of about 338 494 km² land area in total, divided in multiple small islands. Due to its distinct and varied geography this region contains many endemic and unique species of flora and fauna and has been divided into a number of distinct ecoregions; the mountain and lowland areas of Sulawesi, North Maluku, Buru and Seram in Maluku, the Lesser Sunda Islands (with Sumba a distinct ecoregion in its own right), Timor, and the islands in the Banda Sea.
The Wallacea has a total of 223 native mammal species. 126 of them are endemic to this region. An astonishing 124 bat species can be found in this area. Sulawesi, as the biggest island in this region, has the highest number of mammals. 136 species to be exact, of which 82 species and one-quarter of the genera are endemic. Remarkable species such as anoa (Bubalus depressicornis) and babirusa (Babyrousa babyrussa) live on this island. At least seven species of macaques (Macaca spp.) and at least five species of tarsier (Tarsius spp.) are also unique to this island.
650 bird species can be found in Wallacea, of which 265 species are endemic. Among the 235 genera represented, 26 of them are endemic. 16 genera are restricted to Sulawesi and its surrounding islands. Approximately 356 species, including 96 endemic bird species live on the island of Sulawesi. One of them is the maleo (Macrocephalon maleo), a bird currently seen as endangered and found entirely within the Wallacea.
Reptiles and Amphibians
With 222 species, of which 99 are endemic, the Wallacea has high reptile diversity. Among these are 118 lizard species, of which 60 are endemic; 98 snake species, of which 37 are endemic; five turtle species, two of them are endemic; and one crocodile species, the Indo-Pacific crocodile (Crocodylus porosus). Three endemic genera of snake can be found only in this region: Calamorhabdium, Rabdion, and Cyclotyphlops. One of the most famous reptile in the Wallacea is probably the Komodo dragon (Varanus komodoensis), known only from the islands of Komodo, Padar, Rinca, and the western end of Flores.
58 native species of amphibians can be found in Wallacea, of which 32 are endemic. These represent a fascinating combination of Indo-Malayan and Australasian frog elements.
There are about 310 species of fishes recorded from the rivers and lakes of Wallacea, 75 species of them are endemic. Although little is still known about the fishes of the Moluccas and the Lesser Sunda Islands, 6 species are recorded as endemic. On Sulawesi, there are 69 known species, of which 53 are endemic. The Malili lakes in South Sulawesi, with its complex of deep lakes, rapids and rivers, have at least 15 endemic telmatherinid fishes, two of them representing endemic genera, three endemic Oryzias, two endemic halfbeaks, and seven endemic gobies.
There are about 82 species of birdwing butterflies recorded in Wallacea, 44 of them are endemic. 109 tiger beetle species are also recorded within this region, 79 of which are endemic. One of the most astonishing species is perhaps the world’s largest bee (Chalicodoma pluto) in the northern Moluccas, an insect in which the females can grow up to four centimetres in length. This bee species nests communally in inhabited termite nests in lowland forest trees.
About 50 endemic mollusks, three endemic crab species, and a number of endemic shrimp species are also known from the Wallacea.
West Papua and Papua
The fauna of this region comprises a huge diversity of mammals, reptiles, birds, fishes, invertebrates and amphibians, many species of which are of Australasian origin. Ecoregions here include; the mountains of Bird's Head Peninsula West Papua, the lowlands of West Papua and Papua, the Biak Islands, Yapen island, the lowlands of New Guinea's northern coast, the mountain ranges behind the northern coast, medium and high elevations of the New Guinea Highlands, the lowlands and the swamplands of the southern coast, and finally areas of mangrove swamp scattered around the coast.
Although 45% of Indonesian region is still inhabited and covered by tropical forests, high growth of Indonesian population, with its industrialisation, has slowly affected the existence of fauna in Indonesia. Moreover, wildlife trade has also worsened the condition of Indonesia's charismatic fauna, including rhinoceross, orangutans, tigers, and certain species of amphibians. Up to 95% of animals sold in markets are taken directly from the wild, rather than from captive breeding stock; and more than 20% of the animals died in transportation. As of 2003, The World Conservation Union lists as endangered 147 mammals, 114 birds, 91 fish and 2 invertebrate species.
Some of the richest habitats have been protected since the early 20th century under Dutch Colonial law. Indonesia's first national parks have been established in 1980, and the network has been rapidly growing since, reaching a total of 50 declared national parks in 2009. Six of these are also World Heritage Sites and 3 are wetlands of international importance under the Ramsar convention.
Around 40 primates from 200 primate species in the world found in Indonesia forests. 4 Indonesian primates were includes among the 25 most endangered primates in the world, they are Sumatran Orangutan (Pongo abelii), Siau Island tarsier (Tarsius tumpara), Javan slow loris (Nycticebus javanicus) and the Pig-tailed langur (Simias cocolor).