All About Gorillas

 Gorilla, (genus Gorilla), primate genus that includes the largest apes. The gorilla is one of the closest surviving cousins of humans; approximately 10 million years ago, both groups shared an ancestor. Only the chimp and the bonobo are more closely related. Gorillas are found only in equatorial Africa's lush woods. According to the majority of sources, there are two species and four subspecies. The western gorilla (Gorilla gorilla) is divided into two subspecies: the western lowland gorilla (G. gorilla gorilla), which is found in lowland rainforests from Cameroon to the Congo River, and the Cross River gorilla (G. gorilla diehli), which is found in a small forested region along the Cross River that separates Nigeria and Cameroon. The eastern gorilla (G. beringei) is also subdivided into two subspecies: the eastern lowland, or Grauer's, gorilla (G. beringei graueri), which is found in the lowland rainforests of eastern Democratic Republic of the Congo (Kinshasa), and the mountain gorilla (G. beringei beringei), which is found in the montane rainforests and bamboo forests of the highland terrain north and east of (Kinshasa).

The gorilla is strong and robust, with an unusually thick, strong chest and projecting abdomen. Both the skin and the hair are dark. The nose is large, the ears are small, and the brow ridges are pronounced. Adults have lengthy, muscular arms that are around 15%–20% longer than their stocky legs. Males are approximately twice as hefty as females and can reach a height of approximately 1.7 metres (5.5 feet) and a weight of 135–220 kg (300–485 pounds) in the wild. Both sexes of captive gorillas can become quite fat and thus significantly heavier. A wild adult female is about 1.5 metres tall and weighs between 70 and 90 kilograms. Gorillas lack hair on their faces, hands, and feet, while older males have a bare chest. G. beringei beringei has a longer hairstyle than the other three subspecies. Adult males have a large crest on top of their heads and a "saddle" of gray or silver hairs on their lower backs—hence the term "silverback," which is frequently used to refer to mature males. This saddle is significantly more noticeable on eastern gorillas (G. beringei), which are jet black, than on western gorillas (G. gorilla), which are a deep gray-brown color.

Gorillas live in stable family groups of between six and thirty individuals. The groups are commanded by one or two related silverback males, typically a father and one or more of his sons. Occasionally, brothers become the helm of a group. The remainder of the group consists of females, newborns, juveniles, and young adult males (blackbacks). Adult females join the group from outside, and the young are silverback progeny.

The gorilla is predominantly terrestrial and active throughout the day (diurnal), usually walking on all four limbs with a portion of its weight carried on the knuckles of its hands. This method of mobility, dubbed knuckle walking, is also used by chimps. Gorillas occasionally stand upright, primarily while exhibiting. Females and juveniles climb more than males, mostly because many vegetation is incapable of supporting males.

Their diet is entirely vegetarian; eastern gorillas consume leaves, stalks, and shoots, while western gorillas consume far more fruit. Although gorillas dislike water in general, in some regions, such as the Sangha-Ndoki region on the borders of Cameroon, the Republic of the Congo (Brazzaville), and the Central African Republic, they wade waist-deep into swampy clearings to feast on aquatic plants. Gorillas spend the majority of their time foraging and resting, with the troop walking only a few hundred meters between daily feeding sessions. Each group roams a home range of approximately 2–40 square kilometers (0.77–16 square miles), though numerous groups may occupy the same area of woodland. Each gorilla constructs its own rudimentary sleeping nest at dusk using bending branches and vegetation. Each night, a new nest is constructed on the ground or in the trees.

The gorilla is far larger than the chimp, its closest relative, and has a less raucous personality. Although it is a rather peaceful animal, the gorilla's range of noises includes grunts, hoots, a frightening alarm bark, and the aggressive male's roar. Although much has been written about the gorilla's ferocity, studies indicate that it is unaggressive, even shy, until it is disturbed excessively. Intruders may be confronted by the group's leader silverback, who may demonstrate aggressive behavior in an attempt to defend his dependents. These displays are frequently characterized by chest thumping, vocalization, or brief rushes toward the intruder, followed by a subtle departure. Males and females both do chest thumping, but it is more louder in males due to the resonant sound created by the air sacs in the throat and chest. Chest pounding is frequently performed as part of a ceremony that may also include sideways running, tearing at vegetation, and slapping the ground. Along with threatening intruders (gorilla or human), these displays serve as a means of communication between groups and are frequently employed to maintain the group's dominance structure.

Gorillas lack the curiosity and adaptability of chimps cognitively, but they are more calm and persistent. Captive gorillas have showed a talent for problem solving, as well as insight, memory, and anticipation of experience. They appear to be as good as chimps at picking up on human sign language. Certain gorillas are capable of recognising their own image in a mirror, indicating that they have a limited degree of self-awareness. This is a trait shared by chimps and orangutans. That capacity is shared by only a few other nonhuman species.

Female gorillas in the wild give birth approximately every four years; there is no set breeding season. The gestation period is approximately eight and a half months, and most births are single, however twins do occur seldom. A baby gorilla weighs approximately 2 kg and is completely defenseless for the first three months of life, when it is carried in its mother's arms. The baby gorilla spends the night in the mother's nest and rides on her back during the day. Female gorillas achieve reproductive maturity around the age of ten and then join another group or a lone silverback. Males attain sexual maturity around the age of 9, but do not procreate until they reach physical maturity as silverbacks around the ages of 12–15. The majority of male gorillas abandon their birth group in search of females to form their own family group. This may include some conflict, as a young male may infiltrate an established group and attempt to "kidnap" females, occasionally murdering infants. Occasionally, a male may remain in his birth group and become its second silverback, mating with some of the females and eventually succeeding his father as leader when he aged or dies. Wild gorillas have a life expectancy of roughly 35 years, however captive gorillas have reached their forties.

The gorilla has become increasingly scarce across its range as a result of human-caused forest habitat destruction, as well as big-game hunting and overcollection by zoos and research institutes. A more recent issue is hunting for bushmeat, particularly to feed logging crews. With regards to eastern gorillas, both the eastern lowland gorilla (G. beringei graueri) and the mountain gorilla (G. beringei beringei) have been designated as critically endangered subspecies by the International Union for Conservation of Nature (IUCN). Eastern lowland gorillas and mountain gorillas are estimated to number less than 5,000 individuals combined, with the mountain gorilla population being only 1,000 individuals. Mountain gorilla populations continue to fall as a result of habitat loss caused by human activities including as farming, grazing, forestry, and, more recently, habitat devastation caused by refugees. Simultaneously, ecotourism, which involves visitors visiting gorillas in their natural habitat, has aided in the mountain gorilla's protection.

While western gorillas are more common than their eastern counterparts, the IUCN continues to list both subspecies as critically endangered due to population declines caused by poaching and habitat destruction. Cross River gorillas are the most endangered, with adults numbering less than 250. Western lowland gorilla population estimates, on the other hand, are significantly greater. They more than doubled in 2008, when a previously undiscovered population of over 100,000 was discovered in the marshes of the Lac Télé Community Reserve in the Republic of the Congo. Ecological studies, on the other hand, continue to chronicle the western lowland gorilla population's continued decline, from an estimated 362,000 in 2013 to 316,000 in 2018.