Eastern Gorilla

## Description

The Eastern gorilla is the largest primate in the world. As compared with other gorillas, the Eastern gorilla has a smaller nose, shorter arms, longer hair as well as larger jaws and teeth. Mature males are often called silverbacks due to a large patch of hair on their backs, which is silver or grey in color. In addition, males have sharp and large canine teeth. When under stress, apocrine glands in the armpits of females emit a strong smell. The arms of the Eastern gorilla are long and muscular, the head is huge and the legs are short. The silky and long coat of this primate varies from blue-black to brownish grey.

## Distribution

There are two recognized subspecies of the Eastern gorilla: the mountain gorilla restricted to the mountain rainforests and subalpine forests of the eastern Democratic Republic of the Congo, southwestern Uganda, and Rwanda; and Grauer's gorilla occurring across the forests of the Albertine Rift in the eastern Democratic Republic of Congo.

## Behavior

They are diurnal, spending 40% of the day resting, 30% traveling, and another 30% - feeding. They rest and sleep in nests, placed on steep slopes, in trees, or on the ground. Eastern gorillas gather in social units called harems, which contain a male and females with their young. Gorilla harems are not territorial, though conflicts and encounters can happen, particularly when a lone male gets into contact with members of the harem. Grooming is a common activity for these gorillas, usually occurring between males and females as well as among females. These animals are very calm, and care for their babies, forming strong bonds within the group. Eastern gorillas use a wide variety of communication forms, interacting with each other or warn intruders to keep away.

## Diet

Eastern gorillas are folivores, feeding mainly upon leaves, roots, stems, vines, shrubs, bamboo as well as pith of herbs. They also consume flowers, fruit, berries, fungi, wood, the bark of trees, and epithelium, which is stripped from roots. In addition, these primates will sometimes eat invertebrates.

## Reproduction

These animals have polygynous mating system with the dominant male of the group having the exclusive right of mating with all females of the group. The Eastern gorillas mate all year round. The gestation period lasts 8.5 months, yielding a single, dependent baby. The infant is carried by its mother, able to crawl only at 9 weeks old and starting to walk at the age of 30-40 weeks. The mother breastfeeds the young for about 1 year, though weaning often occurs no sooner than 3 years old. After weaning, the young continue living with their mother for another year. Female gorillas reach reproductive maturity at 10 years old while males don't breed until they are at least 15 years old.

## Population

### Threats

Poaching is among the major threats to this species’ population. The Eastern gorillas are poached for their body parts while juveniles are captured by zoos and private collectors. Another notable threat is the civil war in the region, which has caused a number of fatal accidents. Tourism, which so far supported the survival of the Eastern gorillas, has recently become a threat due to a large number of people coming into contact with these animals and thus putting them at risk of catching a human disease.

### Number

According to IUCN Red List, the total population size of the Eastern gorilla is fewer than 5,000 individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List and its numbers today are decreasing.

### Ecological niche

Feeding upon vegetation, these primates play an important role in plant communities. Due to consuming plants, these gorillas become seed dispersers, helping many large fruit trees survive.

## Fun Facts

Gorillas are extremely intelligent animals, using tools in daily life as well as different ways of communication. They have 25 various sounds, by which these animals communicate with each other. Koko, a renowned female gorilla, that has been born captive, started learning sign language at 1 year old. At 40 years old, this primate had a library of approximately 1.000 signs and was able to comprehend about 2.000 English words.

Adult males, that are over 12 years old, are called silverbacks due to the hair on their back, which changes its color, turning from black to gray.

These primates have 5 fingers on each hand and 5 toes on each foot, just like humans.

They have 32 teeth and small ears on the sides of their head.

Noseprints of gorillas, just like human fingerprints, are unique and can help identify an individual.

A scientific study, conducted in 2012 on captive gorillas, showed that females use so-called "baby talk" when communicating with their young. The study also found that the gestures they use to communicate with their babies are more repetitive and more tactile.