Gorillas are the largest extant genus of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. The DNA of gorillas is highly similar to that of a human, from 95–99% depending on what is counted, and they are the next closest living relatives to humans after the bonobo and common chimpanzee.
Gorillas can climb trees, but are usually found on the ground in communities of up to 30 individuals. These troops are organized according to fascinating social structures. Troops are led by one dominant, older adult male. . . The leader organizes troop activities like eating, nesting in leaves, and moving about the group's 0.75-to16 square-mile (2-to-40-square-kilometer) home range.
Gorillas are shy and peaceful. The only natural enemy of gorillas has always been human beings. Gorillas are still hunted for meat and trophies in some parts of Africa, and they are caught in traps set for other animals. Now the most serious threat to free-living gorillas is the human population explosion. As more and more people take over the land for agriculture, logging and other development, gorillas have nowhere left to go.
Eastern gorillas are herbivorous, with a heavily foliage-based diet. They have smaller home ranges than western gorillas as foliage is more abundant than fruit. They are diurnal but most foraging occurs in the morning and late afternoon. At night they build nests by folding over vegetation, usually on the ground.
The considerable dietary differences between mountain, western, and eastern lowland gorillas impact home range size and social behavior. Despite these differences, though, all gorilla groups exhibit synchronized activities and, throughout the day, alternate between rest periods and travel or feeding periods.
Female gorillas give birth to one infant after a pregnancy of nearly nine months. Unlike their powerful parents, newborns are tiny—weighing four pounds (two kilograms)—and able only to cling to their mothers' fur. These infants ride on their mothers' backs from the age of four months through the first two or three years of their lives.
Population estimates based on nest counts, known areas of available habitat, and population density reveal startlingly low numbers for some subspecies: as high as 110,000 (G.g. gorilla), 250 to 300 (G.g. diehli), 17,000 (G.b. graueri), and 700 (G.b. beringei). There are about 350 gorillas in zoos in the United States, all of them are western lowland gorillas.
The eastern lowland gorilla is the largest. Adult male gorillas have silvery white "saddles" that inspired the name "silverback" for these animals. On two legs, adult male gorillas stand about five a half feet tall (rarely a bit taller). They weigh between 300 and 400 pounds. Females are smaller, standing up to five feet tall and averaging about 200 pounds.
Gorilla of different subspecies vary in coat length, hair color, and jaw and teeth size. Individuals vary, but many western lowland gorillas (G. g. gorilla) have brownish-gray coats, unlike the often blackish coats of the mountain (G. b. beringei) and eastern lowland (G. b. graueri) gorillas.
The largest of the living apes, the gorilla has a characteristically heavy body shape and shaggy dark coat. Until recently it was considered a single species, but DNA evidence has led to the recognition of the eastern and western populations as distinct species; Gorilla beringei and Gorilla gorilla respectively.
[Gorilla parents use] stern vocalizations (pig-like grunts), body posturing and strong looks. Gorillas also chuckle, smile and purr. They are gentle and intelligent. Gorillas feel deeply and remember for years. Groups are not territorial and generally avoid each other, but when they do meet, sometimes threats and fighting occur, with the silverback remaining to challenge the attacker while the rest of the group flees.