Orangutan

The largest of the Asian primates, the orangutan, belongs to the Hominidae (or Great Apes) family whose members also include humans, chimpanzees, and gorillas.  While fossil records indicate that this primate once inhabited much of Southeast Asia, its current populations are restricted only to the islands of Borneo and Sumatra.  Moreover, recent genetic evidence has revealed that the Bornean orangutan (Pongo pygmaeus) is actually a different species from its Sumatran relative (Pongo abelii).  Additionally, three subspecies of Pongo pygmaeus (P. p. morio, P. p. pygmaeus, and the most common P. p. wurmbii) are recognized based on the mammal’s home range distributions
In terms of physical description, the Bornean and Sumatran orangutans exhibit a characteristic ape-like shape, shaggy reddish fur, and long powerful arms with strong, grasping hands and feet that enable individuals to gracefully traverse the forest canopy by brachiating and grabbing hold of nearby tree branches.  Both species also demonstrate similar sexual dimorphism.  Adult males are distinguished by their larger size, well-developed throat pouch, and flanges, known as cheek pads, on either side of the face.  Yet, there are subtle dissimilarities in body build, coat characteristics, and facial features that serve to differentiate one species from the other in addition to their geographic separation.
Although uniquely adapted for survival as the largest tree-dwelling mammal in the world, orangutan populations have been steadily declining in both range and numbers for many years. They are currently in danger of becoming extinct within the next few decades.  Humans have a long history of hunting this particular primate for various reasons including food, exhibition in zoos, or illegal pet trade, but the main threat to the orangutan’s continued existence derives from loss of habitat.  In the last half-century, close to 80% of orangutan territory has been exploited by illegal logging operations, gold mining, and conversion of pristine forests to permanent agricultural sites, in particular palm oil plantations.   Between 1997 and 1998, it is believed that around one-third of the island’s orangutan species subsequently perished following forest fires caused by slash and burn farming techniques in Borneo.
Because this primate inhabits densely forested regions, it is difficult to determine precise population sizes; however, estimates place the current number of Bornean orangutans at approximately 55,000.  Sumatran populations have fared much worse, declining as much as 50% during the 1990s, such that current censuses indicate only about 7,500 individuals remain.  Taking into account that both species have extremely slow reproductive cycles and require extensive home ranges to support their dietary needs, their populations have become highly vulnerable to excessive mortality. The population will require a long time to recover even if government-sponsored protective measures can be routinely instituted and sustained.
In their native environments, Bornean and Sumatran orangutans often display a semi-solitary social organization, which is quite uncommon among great apes.  Individuals usually travel alone or in small groups consisting of two females, their dependent young, and occasionally an adult male, although temporary travel bands and feeding aggregates have been observed when quantities of food are plentiful.  Generally, males and females come together only to mate, at which time dominant males become polygamous.  Although there is no distinct breeding season, females typically give birth only once every five to eight years due to the lengthy gestation period (of about nine months) and the prolonged maternal investment in offspring development.  In contrast, adult males can afford only sporadic parental care since their reproductive success largely depends on the formation and maintenance of dominance hierarchies with other males whose home ranges overlap with their own.
With regard to their daily activities, orangutans are diurnal and almost exclusively arboreal.  A typical routine begins with early morning foraging on fruit and other items such as leaves, insects and tree bark.  Afterward, there is midday rest, late afternoon travel, and early evening preparation of a nighttime nest.  These nests are normally constructed from branches and other vegetation obtained from the forest canopy, and they resemble platform-style beds situated 40 to 60 feet above ground.