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 ·Orangutan |
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Description: Orangutans have coarse, long hair that varies in color from orange to brown or maroon in adults. Males have a large throat pouch and develop cheek flanges. An infant’s face darkens with age. Full grown males weigh from 225-300 pounds, and females between 100-130 pounds. An orangutan’s arms are longer than its legs; the arm span can reach up to seven feet. Orangutans in the wild live about 35 years, in captivity they can live as long as 50 years. Diet: Orangutans are primarily herbivores, eating fruit (about 60% of their diet). Durian (just before it’s ripe), rambutans and strangler figs are favorites. When fruit is not plentiful they will eat leaves, shoots, bark, and flowers. They will also eat insects, eggs and small vertebrates. Males eat more termites than females. They get water from wet vegetation, tree holes and their own wet fur. They ignore several species of fruit including some figs. At the zoo they feed on monkey chow and a variety of fruits and vegetables including apples, oranges, pears, corn, carrots, broccoli, lettuce, yams and green peppers. Occasionally they receive kiwi, raisins, nuts, strawberries and grapes. Behavior: Unlike most apes, orangutans are considered to be solitary or semi-solitary. Mature males limit their socializing to sexual encounters. Females, however, will travel with their offspring and have territories that overlap with their own mothers. Although they are the least vocal of the great apes, orangutans do have vocalizations to attract females, announce their presence, or express discontent (a “kiss squeak” noise). Long calls from the males keep the males apart and announce their availability to females. Orangutans, being arboreal (tree dwelling) and slow moving, build nests high in the canopy with tree branches, similar to that of chimpanzees. Orangutans also build roofs to protect them from rain during heavy downpours. They generally do not sleep in food trees, they only nap in them. They are more vulnerable to nocturnal predators such as the clouded leopard while sleeping, so they nest higher in the trees. They move through the trees grasping the branches with hands and feet. They dive, brachiate (swinging with arms from branch to branch) and tree sway. They occasionally walk bipedally (using only two limbs) on the ground. Orangutans are diurnal, and spend a great deal of their day searching for and consuming food. They are very intelligent and use tools, such as sticks or leaves, to gather and eat food, scratch themselves, or make their shelter. Although the territory of a male orangutan overlaps that of several females, mature males may come in contact with each other. The males will display aggressive behavior such as staring, inflated throat pouches and shaking branches. Orangutans also use their lips to express fear or when trying to appease another animal. If neither backs down, grabbing and biting may occur. Breeding: Females are sexually mature at 7- 10 years of age, but don’t usually have offspring until 12 years. Males are sexually mature at 9-11 years. When a male finds a female in estrus he establishes a consortship (temporary association) leading to repeated copulations over several days. Sub-adults are not picky and will copulate with any female, willing or not. These encounters do not usually end in pregnancy. Mature males seem to want females that are mature and capable of taking care of an infant. Orangutans have a gestation period of 230 - 260 days and they only give birth approximately every eight years due to the high dependence of young. At birth the baby weighs about 3.5 - 4.5 pounds. The baby will travel throughout the canopy by hanging onto its mother’s back and the mother is the exclusive care giver. In the first year the infant is totally dependent on its mother. They are born with very few instinctive behaviors, and learn most of what they need to know from their mothers. At two or three years the juvenile will start to venture away from its mother, but never too far, and will still share a sleeping nest. It will also start learning to build a nest. A juvenile stays in the vicinity of its mother until it is 6 or 7 years old. Adaptations: Long arms and hands with long fingers help with climbing. Like humans, orangutans have opposable thumbs. Also, their feet function as hands, providing great grasping abilities, as if they have four hands. Cheek flanges and long hair on the males aid in aggressive displays toward rival males. Male’s throat pouch inflates during calling which adds resonance to long morning calls. These can be territorial calls, sexual display calls or position signals used as a spacing function. Conservation: Orangutans are critically endangered due to rainforest deforestation and poaching. The use of land for logging, mining, farming and palm oil plantations in these areas is contributing to the decline of the species. Although there are heavy fines for hunting, capturing, selling and transporting orangutans, that does not stop poachers. Orangutans are wild animals and should not be kept as pets; as they grow old, they become very strong and may be aggressive. Miscellaneous: In Malay “orang” means “person” and “utan” is said to mean “forest” in hutan (one of the island languages). Thus orangutan literally means “Person of the forest”. Orangutans have a high intelligence. Tests indicate that their intelligence is similar to that of chimpanzees and gorillas. In the wild they use their intelligence to solve problems related to arboreal travel and food processing. In captivity family groups are readily assembled and live together as compatibly as other primates that live together in nature. In the wild, often the seeds from the fruits are swallowed and then deposited in the feces. The feces fall to the ground, enabling the orangutans to be a great disperser of seeds. Sources: Tuttle, Russel H. Apes of the World. Tuttle Noyes Publications, 1986. Preston-Mafham Rod and Ken. Primates. Facts on File, 1992. http://wcs.org/home/getinvolved/orangutans
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Scientific Name: Pongo pygmaeus (Bornean), Pongo abelii (Sumatran)