Species: P. pygmaeus
The Bornean orangutan is one of three subspecies of orangutan and can only be found in Southeast Asia on the island of Borneo. Growing up to 5’ tall, these apes can weigh from 70-190 pounds, with arms almost long enough to drag the ground when standing upright. Living in the thick rainforests, orangutans are the most arboreal of the great apes. In Malay, the word “orang” means person, and the word “hutan” means forest. The inhabitants of the island call them “people of the forest”. The name orangutan was first coined in English 1691 and the genus pongo was first termed by English sailor Andrew Battell while being held prisoner in Angola by the Portuguese.
The island of Borneo is the only place on Earth where Bornean orangutans can be found. They have close neighbors in Sumatra and Indonesia, the Sumatran orangutan, but these are not sympatric with the Bornean orangutans. The Bornean orangutan is unique as it can only be found on the island of Borneo itself. The jungles they inhabit there are some 500 or more meters above sea level, making them high in altitude. The loss of this habitat is becoming very apparent as logging and farming are big industries on the island with few other resources. They combine climbing and brachiation to move through the trees and seek out food but also forage on the ground for various food resources.
Bornean orangutans eat a lot of fruit and are called the gardeners of the forests for their endozoochory. Primarily frugivores, they spend up to 90% of their foraging time eating bark and vegetation when fruit supplies are limited. Although being primarily solitary animals, they will travel in small groups to forage between fruiting trees. They have been observed to practice geophagy, the eating of soil for the addition of minerals in their diets.
In addition to being terrestrial quadrupeds, orangutans are well suited for life in the dense jungle of Borneo, where they also spend a good deal of time in the trees as the largest of arboreal apes. They have long arms that almost drag the ground as they walk which makes them supreme brachiators and very strong. Their coat is a thick orange color which is bright in coloration in contrast to the neighboring Sumatran orangutans, whose coat is not as shiny. These thick coats often form some very intense dreadlocks over time. They also sport very large cheek pads that signal maturity and are supported by connective tissues.
Bornean orangutans are very solitary animals, often considered to be the most solitary of all the apes. Adult males and independent adolescents of both sexes range alone, while adult females range with their dependent offspring. Sub adults may travel in small groups but this will discontinue in adulthood as they seek out their own territory. Males have large ranges that overlap with resident female’s smaller ranges. This gives the male the opportunity to mate with the resident females in his range. These resident females practice female philopatry, as the females settle in ranges that overlap with their mothers. However, no interaction takes place between the mother and her female offspring and no bonding has been observed once maturity is reached in the female offspring.
Similar to humans, female orangutans have a nine month reproductive cycle with a 30 day menstrual cycle. They do not show signs of external estrus and only give birth once every six or seven years, as it is very costly to feed herself and her infant and maturity is very slow. Offspring are the most altricial of all apes and are considered immature until 9-12 years of age. Females aren’t sexually mature until they have their first infant, which can take up to 16 years. Males don’t reach adulthood until 18-20 years, which is signaled by the development of a laryngeal throat pouch, cheek pads, and a long call that can be heard up to 1.2 miles away.
Because they mature and reproduce so slowly it can take decades to restore an orangutan population. Females selectively mate so doing this in captivity is not always the easiest thing to do. Bornean orangutans have no natural predators, with their biggest threat being humans. Due to deforestation, farming, and logging on the island of Borneo, these animals face a great threat because of the loss of their habitat. This places them on the endangered list and is considered to be a protected species on the island of Borneo.
Blaze is a Bornean orangutan living in the Atlanta Zoo. Her date of birth is January 20, 1996 and was born in the Audubon Zoo, in New Orleans, Louisiana. She arrived at the Atlanta Zoo in 2010 and during enrichment activities or when interacting with the keepers will make squeaking noises. Her favorite treat is corn and will sometimes walk around covered in sheets. She gave birth to Pongo, a male Bornean orangutan, while at the Atlanta Zoo on January 10, 2013. Pongo was delivered by Caesarean section with the aid of a team of doctors consisting of human obstetricians, veterinary anesthesiologists, and neonatologists.