Once found throughout much of Southeast Asia, the orangutan is today restricted to just two islands in the Indo-Malay
The only great ape found in Asia, there are three species of orangutan
The three species vary in both physical characteristics and behaviour. The Bornean species is a slightly darker colour than the Sumatran species, is larger and more robust in appearance, and adult males have wider cheek pads, which tend to protrude forward. The two Sumatran
Although both species of orangutan are known for their solitary nature, both Sumatran orangutan species tend to be more social, are more frugivorous (fruit-eating) and exhibit more evidence of complex tool use than Borneans.
Population estimates have been varied over the years but the most recent estimates suggest the following: Pongo pygmaeus: 70-100,000; Pongo abelii: 13,600; Pongo tapanuliensis: 800.
Under the IUCN (International Union for Conservation of Nature) Red List, all orangutans are classified as critically endangered.
Left: Male Bornean orangutan (P. pygmaeus); Center: Sumatran orangutan (P. abelii); Right: Tapanuliensis orangutan (P. tapanuliensis)
Orangutans are the largest arboreal primate in the world, spending almost all of their time in the trees, and are unique amongst primates in leading lives that are best described as semi-solitary. Unlike the complex social groupings of gorillas, chimpanzees, bonobos
Orangutans are the slowest breeding of all primates, and at 6-9 years, have the longest birth interval of any land mammal. Born after a gestation period of 8-9 months, orangutans spend the first few years of their life in constant contact with their mothers. Females reach sexual maturity at 10, but will only have their first offspring between the ages of 12-15. Puberty ages for male orangutans are similar, but orangutans are unusual in having two types of sexually mature male, those with the physical characteristics of sexual maturity, flanged males, and those without. Females conceive after a courtship of between 3-10 days, which are usually ended by the female, and males play no part in the upbringing of their offspring. Females will usually have no more than 3 offspring in their lifetime, which is estimated at 45 years in the wild.
With these factors combined, orangutan populations, especially small fragmented ones, are at a considerable risk of extinction. With such a low birth rate, they don't have the capacity to recover from population losses, and even a slight rise in the adult female mortality rate, by just 1-2%, can drive a local population to extinction.
Orangutans are primarily frugivorous, meaning their diet is made up mostly of fruit, but they will also supplement their diets with leaves, bark, insects and, occasionally, meat, especially in periods of low fruit
By consuming large quantities of ripe fruit, orangutans are one of the most important seed dispersers in the tropical rainforest. Selectively choosing fruit whose seeds are adapted to withstand passage through the gut, the seeds are then excreted at various different positions throughout the