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 ado
lescents (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 age of eight and are not completely grown until the age of fifteen. Sumatra
flange development begins at the age of ten and is not complete until the early
twenties. The flange in the Sumatra orangutan lie flat against the face and give a wide
facial appearance especially in the mid facial region. The life expectancy of orangutans
in the wild is not known, but captive orangutans have been known to live up to fifty
years.
Orangutans are sexually dimorphic. Males are approximately twice the size of females
and weigh about 220 lbs. and reach a height of five feet. It is believed that the males
larger size may be an adaptation for mating because there is strong competition among
males for females. The pendulous laryngeal sac, when inflated, increases the tone of the
animals voice, producing "long calls". In both subspecies (Borneo and Sumatran)
calling acts as " a spacing mechanism between the males and also advertise the location
of the highest ranking male to the mature females." (Rijksen,1978). The long call of the
Borneo male is long and drawn out where as the Sumatran is much shorter and has a faster
tempo. The difference may be attributed to the larger throat pouch the Borneo has. The
reason for the different calls is unclear. They may be related to the terrain each
subspecies inhabits. The faster call of the Sumatran may be more effective in the
rugged, mountainous terrain. The longer call of the Borneo may be d
ue to the wide distribution of this race.
A large portion of an orangutans day is spent looking for and consuming food. Their
diet primarily consists of fruit but they also eat leaves, bark, flowers, insects, and
birds eggs. One of their preferred foods is the fruit off of the durian tree, it is
supposed to taste like sweet garlic. After they have finished eating and bedtime comes
around the orangutans build themselves a new nest forty to fifty feet up in a tree made
of boughs.
Like the other great apes (chimpanzees and gorillas), orangutans are highly intelligent.
Tests have indicated that their intelligence is relatively similar. Wild orangutans use
their intelligence to solve problems usually related to arboreal living and food
gathering. In captivity, however, they have been trained to perform tricks and to use
sign language. They have also made tools to throw at humans, get food, and gain
leverage.
Today, the total number of orangutans ranges between 20-27,000. They are now endangered
primarily because their habitat continues to be destroyed and the practice of killing the
mother in order to capture a baby for animal trade. Even though they are protected by
international laws, it is difficult to enforce them.
Orangutans are inhabit the forests on the islands Sumatra and Borneo. Through evolution
and reproductive and geological isolation two sub species have emerged (Borneo and
Sumatra). They generally live alone with the exception of the long term relationship
between a female and her young. When orangutans do meet one another they are very
tolerant and aggression is rare, unless two mature males meet each other. Males maintain
their distance from on another with "long calls", these also advertise their location to
adult females. Orangutans are generally fruit eaters, because fruit is abundant in the
forests they inhabit. They lead a very solitary life. The population continues to
decline because of habitat loss, and fewer than 30,000 orangutans are thought to remain
in the wild.
Tim Sanderson Orangutans (Pongo pygmaeus)
Anth 111
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 ado
lescents (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 age of eight and are not completely grown until the age of fifteen. Sumatra
flange development begins at the age of ten and is not complete until the early
twenties. The flange in the Sumatra orangutan lie flat against the face and give a wide
facial appearance especially in the mid facial region. The life expectancy of orangutans
in the wild is not known, but captive orangutans have been known to live up to fifty
years.
Orangutans are sexually dimorphic. Males are approximately twice the size of females
and weigh about 220 lbs. and reach a height of five feet. It is believed that the males
larger size may be an adaptation for mating because there is strong competition among
males for females. The pendulous laryngeal sac, when inflated, increases the tone of the
animals voice, producing "long calls". In both subspecies (Borneo and Sumatran)
calling acts as " a spacing mechanism between the males and also advertise the location
of the highest ranking male to the mature females." (Rijksen,1978). The long call of the
Borneo male is long and drawn out where as the Sumatran is much shorter and has a faster
tempo. The difference may be attributed to the larger throat pouch the Borneo has. The
reason for the different calls is unclear. They may be related to the terrain each
subspecies inhabits. The faster call of the Sumatran may be more effective in the
rugged, mountainous terrain. The longer call of the Borneo may be d
ue to the wide distribution of this race.
A large portion of an orangutans day is spent looking for and consuming food. Their
diet primarily consists of fruit but they also eat leaves, bark, flowers, insects, and
birds eggs. One of their preferred foods is the fruit off of the durian tree, it is
supposed to taste like sweet garlic. After they have finished eating and bedtime comes
around the orangutans build themselves a new nest forty to fifty feet up in a tree made
of boughs.
Like the other great apes (chimpanzees and gorillas), orangutans are highly intelligent.
Tests have indicated that their intelligence is relatively similar. Wild orangutans use
their intelligence to solve problems usually related to arboreal living and food
gathering. In captivity, however, they have been trained to perform tricks and to use
sign language. They have also made tools to throw at humans, get food, and gain
leverage.
Today, the total number of orangutans ranges between 20-27,000. They are now endangered
primarily because their habitat continues to be destroyed and the practice of killing the
mother in order to capture a baby for animal trade. Even though they are protected by
international laws, it is difficult to enforce them.
Orangutans are inhabit the forests on the islands Sumatra and Borneo. Through evolution
and reproductive and geological isolation two sub species have emerged (Borneo and
Sumatra). They generally live alone with the exception of the long term relationship
between a female and her young. When orangutans do meet one another they are very
tolerant and aggression is rare, unless two mature males meet each other. Males maintain
their distance from on another with "long calls", these also advertise their location to
adult females. Orangutans are generally fruit eaters, because fruit is abundant in the
forests they inhabit. They lead a very solitary life. The population continues to
decline because of habitat loss, and fewer than 30,000 orangutans are thought to remain
in the wild.
|