The finding of a headless orangutan in Buntok, Central Kalimantan, recently, is regrettable. Orang utan is still seen as a pest by the community around the forest that they hunt the animal and kill it. As a matter of fact, orang utan is one of four apes in Asia that are only found in Sumatera and Kalimantan. It is estimated that there are only 14,470 orangutans in Sumatera and 57,350 orang utan in Kalimantan. The population is decreasing due to lessening habitat that has turned into oil palm plantation and mining, also caused by poaching and hunting.
UGM Faculty of Biology graduate student, Dr. Ike Nurjuita Nayasilanan, said orangutans live in the lowlands. Their habit of finding food in these areas make them often encounter human beings. “Both orangutan and humans like to live in the lowlands. In Kalimantan they are fragmented because the highlands there only reach 700-800 m above sea surface. In Sumatera about 75 percent live outside conservation areas,” said Ike disseminating her research on adaptation of orangutan in conservation forests after being released from rehabilitation centres on Friday (19/1) at Faculty of Biology UGM.
Ike assessed that the habit of the orangutan in the lowland has made their population continue to decline while the ape also likes to consume fruit, leaves, rattan, and insects. “Orangutan explores their natural habitat but their movement follows the spread of nesting trees and feeding trees,” she said.
Ike said based on previous research, there was only one species of orangutan, but currently two species have been found in Sumatera, Pongo tapanuliensis and Pongo abelii. Another species in Kalimantan is Pongo pygmaeus. The emergence of two species in Sumatera, said Ike, was highly possible due to the genetic change after the Toba eruption. “Initial assumption was the eruption of Mt. Toba had created the barrier of the eruption,” she said.
Ike added orangutan was also found in Java in the past, proven by the fossils of orangutan in Pacitan. But the extinction of this species in Java, according to Ike, was caused by land conversion due to human population.
Ike’s research on 16 orangutans released to the Batikap hills found out that orangutans live like human beings which is averagely to 60-65 years, some even until 70 years old. But the orangutan in the forest normally reach the age of 55 years old. While at 0-8 years of age, orangutan is breastfed. Before adolescent age of 12 years old, orangutan usually lives with the mother. Male adult orangutan likes to explore the forest for years, but when they grow old, they will return to their initial habitat. “It’s like a homecoming,” she said.
Orangutan generally does activities from sunrise to sunset. They often live on fruit, leaves, rattan, and honey and drink water from tree bark. “There was one unique case when we research the orangutan in Batikap hills, the female likes to use a stick when eating insects,” she concluded.