Endangered Apes: The Gorilla

The gorilla is the largest of the world’s apes, with a large male standing as tall as an average-size man and weighing as much as 450 pounds (205kg). Fully mature male gorillas are called “silverbacks” because of the fact that, by the time they reach about 12 years of age, the hair on their backs has turned silvery gray. Male gorillas can be up to twice the size of females.

Gorilla family groups consist of a dominant silverback and his harem of several females and their young. The group often also includes one or more sub-dominant silverbacks and immature (“blackback”) males. Although silverbacks sometimes fight for dominance, family life, gorilla-style, is a much more tranquil affair than that of chimpanzees.

A gorilla family roams the rainforest floor, eating a diet that largely consists of vegetation, including leaves, plant stalks, pith from the insides of stalks, and fruits. Only younger, smaller gorillas spend much time climbing trees. At night, each gorilla builds a sleeping nest for itself out of leaves; babies and youngsters share their mothers’ nests.

There are two species of gorilla: the Western gorilla and the Eastern gorilla, each of which is divided into two subspecies.

The Eastern gorillas are the mountain gorilla (Gorilla beringei) and the Grauer’s gorilla (Gorilla berengei graueri), also known as the Eastern lowland gorilla. Mountain gorillas and Grauer’s gorillas both live in a number of small, scattered and isolated areas of tropical east-central Africa, with the mountain gorilla living at higher, cooler elevations than the Grauer’s subspecies.

Mountain gorillas and Grauer’s gorillas are both listed as Endangered species. Although fewer than 700 mountain gorillas remain in the wild, the species has actually increased in number over the past few decades due to protections brought on as a result of worldwide interest in the animal’s plight on the part of both conservationists and the public. By contrast, the number of Grauer’s gorillas, estimated at over 16,000 in the mid 1990′s, has been dropping rapidly due to habitat loss, illegal market hunting, and the slaughter of gorilla families in order to capture the babies for an illegal international pet trade.

The Western lowland gorilla (Gorilla gorilla gorilla) is the most numerous subspecies, with a population that was estimated at just under 100,000 during the 1990′s. In spite of this fact, Gorilla gorilla gorilla is listed as Critically Endangered because of the severity of the threats it faces, along with the alarming rate at which its numbers appear to be declining. Not only is the species under intense pressure from illegal market hunting—”bush meat” is a sought after delicacy in West Africa—but large numbers of gorillas have been killed in recent years by human diseases, most notably the dreaded and incurable Ebola virus. Ebola appears to have completely wiped chimpanzees and gorillas alike from vast areas of otherwise intact West African forest.

The second Western subspecies, the Cross River gorilla (Gorilla gorilla dielii), is fast approaching extinction, with a few hundred of the animals surviving (for now) in isolated pockets.

Eastern gorillas are both larger and darker in color than the Western species, with the mountain gorilla being the largest of all four subspecies. The mountain gorilla also has longer hair and a bushier appearance due the fact that it lives in colder areas than the other gorillas.