The Borneo rainforest is 140 million years old, making it one of the oldest rainforests in the world. There are about 15,000 species of flowering plants with 3,000 species of trees (267 species are dipterocarps), 221 species of terrestrial mammals and 420 species of resident birds in Borneo. There are about 440 freshwater fish species in Borneo (about the same as Sumatra and Java combined). It is the centre of the evolution and distribution of many endemic species of plants and animals.
The Heart of Borneo
The orangutans are the two exclusively Asian species of extant great apes. Native to Indonesia and Malaysia, orangutans are currently found in only the rainforests of Borneo and Sumatra. Orangutans are the most arboreal of the great apes and spend most of their time in trees. Their hair is typically reddish-brown, instead of the brown or black hair typical of chimpanzees and gorillas. Males and females differ in size and appearance.
The Life of Borneo
Borneo and Sumatra are the only places on Earth where tigers, rhinos, orangutans, and elephants live together. The forests are home to marvelous creatures like the proboscis monkey, sun bear, clouded leopard, and flying fox bat, and endangered animals like the Sumatran tiger, Sumatran rhino, and pygmy elephant. There are more than 15,000 known plants here, with many more species yet to be discovered. Since 1995, more than 400 species have been identified on the islands, with more than 50 of these species completely new to science. The cultural diversity of Borneo and Sumatra is as distinct and varied as its plant life. More than 60 million people live on these two islands. They are a mix of indigenous peoples and immigrants from other islands in Indonesia, such as Java, as well as other Asian countries. The current population of Borneo is estimated at 18 million. Sumatra is home to 50 million people and is the world’s fourth most populous island.
The plant has no stems, leaves or true roots. It is a holoparasite of vines in the genus Tetrastigma (Vitaceae), spreading its absorptive organ, the haustorium, inside the tissue of the vine. The only part of the plant that can be seen outside the host vine is the five-petaled flower. In some species, such as Rafflesia arnoldii, the flower may be over 100 centimetres in diameter, and weigh up to 10 kilograms. Even one of the smallest species, R. baletei, has 12 cm diameter flowers. The flowers look and smell like rotting flesh, hence its local names which translate to “corpse flower” or “meat flower”. The foul odor attracts insects such as flies, which transport pollen from male to female flowers.
The Pygmy Elephant
The pygmy elephants of Borneo are baby-faced with oversized ears, plump bellies and tails so long they sometimes drag on the ground as they walk. They are also more gentle-natured than their Asian elephant counterparts. Once believed to be remnants of a domesticated herd given to the Sultan of Sulu in the 17th century, pygmy elephants were determined by WWF to be genetically different from other Asian elephants. DNA evidence proved these elephants were isolated about 300,000 years ago from their cousins on mainland Asia and Sumatra. Over time, they became smaller with relatively larger ears, longer tails and straighter tusks. Today, the pygmy elephants of Borneo are the smallest elephants in Asia.
Proboscis monkeys generally live in groups composed of one adult male, some adult females and their offspring. All-male groups may also exist. Some individuals are solitary, mostly males. Monkey groups live in overlapping home ranges, with little territoriality, in a fission-fusion society, with groups gathering at sleeping sites as night falls. There exist bands which arise when groups come together and slip apart yet sometimes groups may join to mate and groom. Groups gather during the day and travel together, but individuals only groom and play with those in their own group. One-male groups consist of 9–19 individuals, while bands can consist of as many as 60 individuals.
The Deep Waters
Borneo is surrounded by the South China Sea to the north and northwest, the Sulu Sea to the northeast, the Celebes Sea and the Makassar Strait to the east, and the Java Sea and Karimata Strait to the south. To the west of Borneo are the Malay Peninsula and Sumatra. To the south and east are islands of Indonesia: Java and Sulawesi, respectively. To the northeast are the Philippine Islands. The largest river system is the Kapuas in West Kalimantan, with a length of 1,143 km (710 mi). Other major rivers include the Mahakam in East Kalimantan (980 km long (610 mi)), the Barito in South Kalimantan (880 km long (550 mi)), and Rajang in Sarawak (562.5 km long (349.5 mi)).Before sea levels rose at the end of the last Ice Age, Borneo was part of the mainland of Asia, forming, with Java and Sumatra, the upland regions of a peninsula that extended east from present day Indochina. The South China Sea and Gulf of Thailand now submerge the former low-lying areas of the peninsula. Deeper waters separating Borneo from neighbouring Sulawesi prevented a land connection to that island, creating the divide known as Wallace’s Line between Asian and Australia-New Guinea biological region