Gorilla

Surface of distribution

Their surface of distribution is divided on two geographically distant main forests of some thousand kilometers, one is located at the east of central Africa, the other in the west of this one.

The West African forest block shelters the most abundant subspecies ( Gorilla gorilla gorilla ). Its population is estimated between: 40000 and: 80000 individuals, divided on the Cameroun, the Guinea Equatoriale, the Gabon, the Congo-Brazzaville and the Central African Republic. A population relic ( Gorilla gorilla diehli ) of some 250 individuals remains in the southern part of the Nigeria at the border with Cameroun.

The East-African block shelters the two other subspecies. Some: 12000 gorillas of the Eastern plains ( Gorilla beringei graueri ) divide themselves into several populations isolated in the east from current the Democratic republic from Congo, in variable habitats energy of the plains to the forests of high-altitude (up to 3300 meters). The gorillas of mountain ( Gorilla beringei beringei ), there remains approximately 600 individuals, live in the forest of Bwindi in Uganda.

Characteristics

The gorilla is after the bonobo and the chimpanzee, from the genetic point of view, the animal nearest to the human one. This relationship was confirmed by the similarities between the chromosomes and the blood groups. Our genome differs only from 2% of that of the gorilla.

Rectified, the gorillas reach a size of 1,75 meter, but they are in fact a little larger because they have the bent knees. The scale of the arms exceeds the length of the body and can reach 2,75 meters.

There exists a great difference in mass between the sexes: the females weigh from 90 to 150 kilograms and the males up to 275. In captivity, nourished particularly well, they reach 350 kilograms.

Peeling depends on the sex and the age. In the oldest males develops on the back a gray fur silver plated, from where their name of “silver plated backs”. The peeling of the gorillas of mountain is particularly long and silky.

Like all the anthropoïdes, the gorillas are deprived of tail. Their anatomy is powerful, the face and the ears are glabrous and they present marked supra-orbital torus.

Longevity: 30 years in kind, up to 50 years in captivity;
Gestation period: 250 to 270 days.

Lifestyle

The gorillas live the forests and are active the day. While the gorillas of the flat countries prefer the wet tropical forests, the gorillas of the mountains live rather in the secondary forests. The gorillas of the mountains are held most of the time on the ground. The gorillas of the flat countries often climb in the trees in the search of food, even the heavy males frequently go up in trees of which the height can reach twenty meters. To ground, the gorillas go to four legs while being pressed on the phalanges of their hands and not on the palms like other monkeys more frankly quadrupeds. Each night, to rest, they build a nest of sheets in hardly five minutes. The gorillas of mountain have their nests with ground most of the time, the gorillas of the flat countries in the trees.

The gorillas live in group with at their head an adult male called “silver plated back”. The composition of the groups varies from two to thirty individuals, the average ranging between 10 and 15. In general each group is composed of an adult male (male with money back), of one or several younger males (males with black backs), several adult females and of some small. When there are several males in a group, only the Mâle dominating can be coupled.

The behavior of the groups is variable, temporary separations for the search for food are frequent. Contrary to much of other kinds of primates in fact generally the females leave the group to find another of them. The groups last generally a long time, sometimes occur of the fights between males to know which will direct the group. If a new male gains, it kills the descent of overcome. One can see in this child murder a biological profit owing to the fact that the females which nurse are not pregnant and, after the death of their small, are quickly ready to copulate again.

The territorial instinct is developed little, several groups seek their food at the same places and avoid the ones the others. As their food is composed especially of sheets, they do not have to go to find it well far, initially because the sheets abound, then because they are not very nutritive, which obliges them at long periods of rest. The gorillas know a whole series of sounds, cries and growls which they use to recognize the members of their group and the foreigners and also like means of intimidation. One knows their way well of striking the chest. One formerly believed this behavior reserved in the older males, one finds it in fact at all. It is probably used to announce its position, or it is about a ritual of welcome.

Gorillas as the chimpanzees use thorny sheets, rich in tannin to get rid of the intestinal parasites which obstruct them. They avalent a more great deal of these sheets without chewing them, so that they dislodge the worms of the intestinal walls.

Population

PNUE (program of the the United Nations for the environment) gives the following estimates in 2003:

Common gorilla:

: 100000 with the Gabon and in the countries bordering.
150 to 200 with the Nigeria
3000 with the Congo-Brazzaville

Gorilla of mountain:

650 between the Rwanda, the Uganda and the Democratic republic of Congo (the survival of this group is largely compromised)

the Ugandan population, according to the censuses, rose with 300 individuals in 1997, 320 in 2002 and 340 in 2007 in the park of Bwindi
Estimation 2007. There would be 720 gorillas of mountain in the world.

Threats

The gorilla of the plains of the west ( Gorilla gorilla gorilla ) is recognized on the international plan like species in danger (statute UICN). Several reasons explain its situation:

Destruction of its habitat;
illegal Hunting for its meat;
fetishistic Beliefs (to be able allotted to its cranium, its bones, its hands);
Smuggling of babies gorillas.

To that, is added the appearance of the hemorrhagic fever due to the virus Ebola and other pathologies. Since November 2000 in Congo-Brazzaville and Gabon, the appearance of the Ebola virus made several hundreds of victims among the large monkeys. The last estimates announce disappearance of almost 5000 gorillas following this epidemic.

References

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