Orangutans

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Orangutans

In Malay orang means "person" and utan is defined as "forest'. Thus

Orangutan literally means "Person of the Forest". Orangutans are found in the

tropical forests of Sumatra and Borneo. They are the most arboreal of the great

apes and move amongst the safety of the trees from one feeding site to the next.

They are so well adapted to arboreal life that they cannot place their feet on

the ground, instead they walk on the outside of their curved foot.

There is a scattered population of orangutan in Indonesian Borneo,

Malaysia Borneo and northern Sumatra. The different habitats have isolated the

orangutan reproductively and geographically from one another creating a "degree

of difference" or two subspecies. There are several different characteristics

between the two subspecies of orangutans and it has recently been suggested that

they may be a separate species. The Borneo male has relatively large cheek

pads, a tremendous laryngeal sac and a square shaped face. The Sumatran male

has small pads and laryngeal sac, a ginger coloured moustache, a pronounced

beard, and a diamond shaped face. Individuals can also be distinguished

chromosomally, biochemically, and by their cranial characteristics.

There is a great deal of individual variety in the orangutan. "Each

orang-utan had a distinct personality and in dealing with such highly

intelligent animals in captivity, the keeper's knowledge of the individual was

probably more important than the knowledge of the overall behaviour patterns "

(Markham, 1980). Orangutan males, however, appear to be totally intolerant of

one another, especially the Borneo males who are even aggressive towards females

and infants. Male orangutans' participation in social groups is limited to

sexual "consortship" with females. However, the Sumatran males tend to stay with

females for a longer period of time usually until the birth of the infant.

They may stay longer with their partner because of the presence of large

predators absent in the Borneo habitat. The orangutan has a menstrual cycle of

29-30 days, menstruation lasting 3-4 days. The Gestation period lasts slightly

less than nine months. Offspring pass through three stages, infancy (0-4),

juvenile (4-7), and adolescents (7-10). Mother young relationship lasts for a

long time, the young usually stay with their mother until they are mature.

Female Orangutans are not sexually mature or fully grown until the age of twelve

and will not have their first offspring until they are at least fourteen. Males

become sexually mature and fully grown at the age of fifteen. The cheek flanges

of the male easily recognize the differences between adults and semi-adults. The

flanges in the Boreal male curve out ward from the face and develop around the

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