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Gorilla Facts
DISCOVERY
The first recorded gorilla sighting (by western civilization) was in the 5th century B.C. by a Roman explorer.
GORILLA TYPES
There are three subspecies of gorillas living in different parts of Africa. The differences between them are very slight.
- Western Lowland Gorilla (gorilla gorilla)
- Eastern Lowland Gorilla (gorilla graueri)
- Mountain Gorilla (gorilla berengei)
POPULATION/DISTRIBUTION
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Western -
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Approximately 10,000-35,000 free-living, 550 in captivity worldwide. Found in Nigeria, Cameroon, Gabon, Congo, Central African Republic and Zaire.
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Eastern -
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Approximately 4,000 free-living. Less than 24 in captivity. Found in eastern Zaire.
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Mountain -
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Approximately 620 free-living. Zero in captivity. Found in 285 square miles in the rain forests of Rwanda, Uganda and Zaire.
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PHYSICAL CHARACTERISTICS
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Height:
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Males 5'6" upright, 4'6" normal stance. Females 5' upright, 3'6" - 4' normal stance.
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Weight:
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Males 300-500 lbs. Females 150-250 lbs. Babies from one to three years weigh between 20-30 lbs.
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Arm Span:
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Up to 9'2'' (one male specimen).
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Color:
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Black or brown-gray fur with black skin on chests, palms and faces. Red heads are common in Camaroon gorillas especially. Males develop a silver back as they mature.
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Stance:
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Gorillas are quadrupedal. They walk on all fours with the soles of their feet flat on the ground and the knuckles of the hands curled and planted on the ground.
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Recognition:
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Gorillas recognize each other by their faces and body shapes. Each gorilla has a unique nose print.
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The differences between mountain gorillas and lowland gorillas are slight and result mainly from adaptation to high altitudes. Mountain gorillas have longer body hair, higher foreheads, longer palates, larger nostrils, broader chests, shorter arms, shorter, wider hands and feet.
GROWTH/MATURATION
Gestation is 8-1/2 months. There are typically 3-4 years between births. Infants stay with their mothers for 3-4 years. Females mature at 10-12 years (earlier in captivity); males 11-13 years, sometimes sooner if they assume leadership early. Lifespan is between 30-50 years.
EATING
Gorillas eat some 200 types of leaves, tubers, flowers, fruit, fungus and some insects. Favorite foods include bamboo, thistles and wild celery. Gorillas do not drink water. They obtain all the moisture they need from the vast amounts of foliage they consume. Males consume approximately 50 lbs. a day.
DAILY ROUTINE
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6am-8am:
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Wake-up
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8am-10am:
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Eat
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10am-2pm:
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Eat, play, relax, sleep
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2pm-5pm:
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Travel 300-6,000 feet - foraging on the way
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5pm-6pm:
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Build nest
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6pm-6am:
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Sleep
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SOCIAL STRUCTURE
Gorillas live in groups of 3-30. A typical group consists of one silverback, one immature silverback, one immature male, three to four adult females, and three to six youngsters under eight years old. A female will usually transfer to another group, particularly if the silverback is her father and there are no other suitable males to mate with. Adult males usually leave after sexual maturity and start their own group or join other "bachelors."
BEHAVIOR/COMMUNICATION
Gorillas learn from their mothers and other adults what to eat, social and sexual behavior and how to rear young. They care for their babies with great affection, patience and playfulness. Energetic, mischevious youngsters are disciplined with 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. To intimidate his opponent, the silverback stands upright to appear larger, beats on his chest, roars, waves his arms, tears branches and charges. This is all done to frighten off, not harm, other males. Distress behavior includes diarrhea and strong, pungent body odor.
PREDATORS
Man is gorilla's only enemy. Because of the actions of male gorillas protecting their groups with such determination from hunters, humans developed a folklore about the ferocity of gorillas. Gorillas' defense of standing and chest-beating make them a perfect target. Like all tightly knit social groups, gorillas will defend their young. They defend them with their lives.
VOCALIZATIONS
Gorillas are generally quiet. They are not physically capable of making the same sounds as humans. They generate about 25 distinct noises, however. Hooting can carry a mile through the forest and is usually exchanged between rival silverbacks. Other vocalizations include screams, grunts (indicating contentment) and high-pitched barks (indicating curiosity).
TOURISM
An hour visit in Africa with gorillas costs about $120, with a maximum of six tourists visiting each habituated gorilla group a day. It can take several hours to reach the gorillas through the dense, mountainous jungle. Safaris start at $3,000. Tourism generates a great deal of money for Rwanda, Uganda and Zaire and helps protect other species as well as the gorilla.
CONSERVATION
Most countries have passed laws protecting the gorillas, but enforcement is difficult in remote jungles where the people exist by hunting. Most zoos around the world have agreed not to purchase gorillas from the wild and participate in a worldwide captive breeding program designed to expand the existing captive population while maintaining a viable gene pool.
FUTURE
The greatest threat to the long-term survival of gorillas is habitat encroachment. The human population explosion in Africa continues to create a need for more land to grow food and house people. Gorillas have no place else to go. They can adapt to no new way of life. Tourism has contributed greatly to saving gorillas, but the future is not at all certain.
SOURCES:
- George B. Schaller & Nan Richardson. Gorilla: Struggle for Survival in the Virungas. 1990.
- Zoological Board of Victoria, Education Service. Gorilla Gorilla Gorilla: All about Gorillas and Other Rainforest Animals. 1990.
- Sara Godwin. Gorillas. 1990.
- Jim Bailey. Gorilla. Save our Species Series) 1990.
- Animal Talk. Pittsburgh Zoo, Fall 1986.
- Boyd Norton. The Mountain Gorilla. 1990.
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