Gorilla Information from the Dian Fossey Gorilla Fund International


Gorillas are one of the four species of great apes that are the closest living relations of humans. The other three species are chimpanzees, bonobos and orangutans. All great apes have arms that are longer than their legs. Great apes are not considered monkeys because they are larger, walk upright for a longer period of time, don’t have tails and have much larger, developed brains than other monkey species.

It was about nine million years ago that the genus Gorilla split from humans and chimps. About three million years after that the lineages of chimps and humans diverged.

Today there are two species of gorillas, each containing several subspecies. The appearances of each of the species are slightly different.
1. Mountain Gorilla. The mountain gorilla is a type of eastern gorilla species. It includes two (some people believe three) subspecies.

Mountain gorilla (Gorilla beringei beringei). They are found in Rwanda, Uganda and the Democratic Republic of Congo, with a total population of only about 700 gorillas. Dian Fossey pioneered gorilla research with the mountain gorillas of the Virungas starting in 1967. Her work is still carried on today by the Dian Fossey Gorilla Fund International (The Fossey Fund).

Grauer's (Gorilla beringei graueri). Previously known as the eastern lowland gorilla, in comparison to mountain gorillas, we know very little about the Grauer’s gorillas. Scientists do not even have a good estimate of the number of Grauer’s gorillas left. Estimates range from approximately 6,000 to approximately 26,000. Most groups of Grauer's gorillas live at heights in between mountainous and lowland forests. Their name comes from Rudolf Grauer, the first Western scientist to identify this subspecies in eastern Congo.

The Fossey Fund is working to document the distribution and density of the Grauer’s gorillas and has partnered with the Tayna Gorilla Reserve to habituate two groups of gorillas for more intensive study.

Eastern and mountain gorillas tend to have a more blackish coat than the other species. Mountain gorillas also have longer and thicker hair which is adapted to their colder mountainous habitat. Grauer’s gorillas are the largest of the four subspecies.

2. Western gorillas. Are found in west and central Africa. They include two sub-species.

Western lowland gorilla, which is the species commonly found in zoos. Recent studies show that there are about 150,000 to 200,000 left in the wild

Cross River gorilla, which number fewer than 300.

Typically, the western species tend to be brownish gray in color and have short, fine hair.


Because of the extensive research begun by Dr. Dian Fossey and continued by the Dian Fossey Gorilla Fund International, the mountain gorilla is perhaps the best understood of all wild gorilla populations.

The Fossey Fund closely monitors nine groups of mountain gorillas in Rwanda's Parc National des Volcans. Staff at the Karisoke Research Center visit the mountain gorilla groups daily and report on their activities, as well as conduct anti-poaching patrols. Other gorilla groups designated for eco-tourism are also regularly monitored.


Where do mountain gorillas live?
The mountain gorillas studied by The Fossey Fund live in the Virunga Volcano mountains, Some of them reach as high as about 4,000 meters (more than 13,000 feet). The forests where the mountain gorillas live are often cloudy, misty and cold. At the bottom of the mountains, the vegetation is very dense, becoming less so as you go higher up. Other animals that live in the forest with the mountain gorillas are duikers (a kind of deer), antelope, tree hyraxes (a small furry animal related to the elephant), golden monkeys, and forest buffalo.

What is mountain gorilla family life like?
Typically, mountain gorillas live in groups that contain one or two adult males (ages 12 years or older, called silverbacks), several younger males (called blackbacks), adult females, juveniles and infants. The largest group recorded by The Fossey Fund is Pablo’s group which reached 65 members at its largest.

The dominant silverback gorilla (so named for the gleaming silver saddle of hair on his back) is in charge of the group's daily travels in search of food. He is also the center of attention during rest sessions and mediates conflicts within the group. The silverback gorilla also protects the group from outside dangers, such as intruding silverbacks from other groups, poachers, other animals and human threats.

The dominant silverback forms special bonds with the adult females in the group and fathers most of the offspring. Mountain gorilla females can begin motherhood around age 10, and will carry a single baby for about 8-1/2 months. Mother gorillas share a very close relationship with their infants for about 4 years, after which another sibling may be born. Mother gorillas hold newborns close to their chest at first, but soon the infant learns how to hold on for itself. Then it learns how to ride on the mother's back, until it is old enough to travel on its own. Their lifespan is 30 to 50 years.

How big do mountain gorillas get?
Adult male gorillas can reach 400 pounds (180 kg), and females can reach about 200 pounds (90 kg). Female gorillas don't have the crest on the top of their heads like the males, and no silver on their backs. When a silverback gorilla is standing upright (say, during a chest beating display), they can be as tall as 5 1/2 feet tall (1.7 meters). A newborn gorilla weighs only about 4-1/2 pounds (2kg)!

What do mountain gorillas eat?
The mountain gorilla diet is mostly plants like celery, nettles, bamboo and thistles, and they are quite particular about what parts of each plant they like to eat. Sometimes they also find ant nests and eat the ants, along with an occasional worm or grub. There isn't much fruit where mountain gorillas live, but they do love to eat the wild berries that grow in their habitat. The mountain gorillas spend a lot of their time traveling in search of food, as plants and trees change with the seasons. The full-grown mountain gorilla diet can include up to 60 pounds (25 kg) of vegetation a day!

How do mountain gorillas communicate?
Everyone who works with the mountain gorillas agrees that they are generally peaceful and gentle. The gorillas that are observed by The Fossey Fund as well as the groups that are visited by tourists, have been habituated to the presence of humans. But this doesn't mean that the gorillas won't sometimes charge, scream or bare their teeth, whether at an outsider or within the group itself. Most of these actions are just meant to serve as warnings, to ward off danger or to prevent a fight.

Mountain gorillas can communicate in a variety of ways, including facial expressions, sounds, postures and gestures. One of the nicest sounds is heard when the group is resting after a period of feeding. This sound is something like a soft purring and is called a "belch vocalization." When the gorillas feel threatened, they can make a variety of loud sounds, like roars or screams. Facial expressions are also used for communication. For example, an open mouth with both upper and lower teeth showing means aggressions. But a closed mouth with clenched teeth may signal anger as well.And, of course, there's the classic chest beating by male gorillas, which is used to show stature, scare off opponents or even to prevent a fight.

Most of the time mountain gorillas travel on the ground on all fours. They will distribute their weight on their knuckles as opposed to their palms, which is why it is called knuckle walking. Sometimes gorillas walk bipedally, but rarely go further than three meters on two feet.

Night Nests
Gorillas use vines, leaves and branches to fashion a rim around themselves and to pad the ground underneath them. These nests can be built within a minute or can take as long as five minutes.


Dian Fossey founded the Karisoke Research Center on Sept. 24, 1967, in Rwanda’s Volcanoes National Park between Mt. Karisimbi and Mt. Bisoke. She recalled this historic event in her book, Gorillas in the Mist: Little did I know then, that by setting up two small tents in the wilderness of the Virungas I had launched the beginnings of what was to become an internationally renowned research station eventually to be utilized by students and scientists from many countries.

There she began a long-term scientific study of the endangered mountain gorillas. She pioneered ways to approach the gorillas so they would accept human observers, and she learned to identify individual gorillas by the wrinkles on their noses. She also promoted active conservation, protecting the gorillas through measures such as armed anti-poaching patrols. At that time, she feared that the mountain gorilla might become extinct by the end of the 20th century, as her mentor, Dr. Louis Leakey, had warned. A census published in 1981 found that the population had fallen to 242 individuals, from a 1960 estimate of 400-500. Now, 40 years later, Fossey might be surprised to learn that some 380 mountain gorillas are known to inhabit the Virunga mountains (according to a 2003 census), a significant increase since her time.

Articles in National Geographic Magazine and Fossey’s book Gorillas in the Mist (later made into a movie by the same name) drew international attention to the mountain gorillas and changed their image from fearful beasts to gentle giants whose genes are 97 percent the same as humans'.

Fossey, whom Rwandans knew as Nyiramachabelli "the woman who lives alone on the mountain" is remembered throughout the world for her heroic struggle to preserve, protect and study the mountain gorilla. After her death in 1985 the Digit Fund became the Dian Fossey Gorilla Fund International (The Fossey Fund), which carries on her work today.

By 1998 Karisoke’s expatriate staff had evacuated five times. The facility was destroyed three times, rebuilt twice, and eventually relocated to Musanze (formerly Ruhengeri). Somehow, the gorillas survived the war years in good condition, despite the greatly increased number of snares set by poachers.
The Fossey Fund currently employs a staff of 125 at the Karisoke Research Center including gorilla trackers, researchers and anti-poaching patrols.


How The Fossey Fund monitors gorillas?

Each morning, trackers locate their assigned gorilla group by going to their night nest locations and then following the trail of crushed vegetation they left behind as they started moving. After finding the group and recording its location via a global positioning system (GPS), the trackers will find each individual in the group and record information on its general appearance and health as well as detailed information on behavior for the The Fossey Fund’s long-term gorilla research database and specific studies.


Gorillas are identified by their unique "nose prints," which are their nose patterns. Every gorilla has their unique nose print. Karisoke researchers use photographs and illustrations of the gorilla’s nose in order to identify and monitor individual gorillas.

Because noseprints can change over the course of an individual’s lifetime, The Fossey Fund updates their noseprint file each year for each of the more than 110 gorillas we monitor.

How do scientists study the gorillas?
In addition to the ongoing research about mountain gorilla life, scientists are now using some of the most up-to-date scientific methods to learn even more. For example, a study is currently underway using DNA samples taken from the gorillas' droppings, in order to learn the exact paternity for each new infant born in a gorilla group. Scientists are also attempting to classify all of the plants in the forests, upon which the gorillas and other species rely for food. Using a new process called hyperspectral remote sensing, they can collect information using aerial photographs, and then compare this information with other data collected on the gorillas and even the poaching activity in the area.

Will the mountain gorilla survive?
The year 2002 marked the 100th year since the mountain gorilla was first scientifically identified as a distinct subspecies of gorilla. The future of the gorillas is most dependent on the protection and survival of the forests in which they live, since they depend on this land for food, safety and normal activities. But the forests are often in danger from growing human populations, and from civil war in the region.

Threats to Gorilla Survival
All types of gorillas in Africa are endangered, primarily due to human activity such as poaching, disease transmission, and habitat destruction. Ultimately, human poverty is the greatest threat to gorillas. Gorillas live in countries in Africa with some of the highest population densities and lowest adult life spans, literacy rates, and standards of living in the world. The challenges that such intense poverty brings to gorilla conservation vary depending on where in Africa the gorillas live. Western gorillas, which inhabit 11 west African countries from Nigeria to Angola, are primarily threatened by illegal hunting for food, habitat loss from logging, and disease specifically the Ebola virus, which has a roughly 95% mortality rate in gorillas. Eastern gorillas are found only in Rwanda, Uganda and the Democratic Republic of Congo, and are not generally hunted for food like their western counterparts. They are primarily threatened by habitat loss when their forests are converted to farmland and pasture; local civil unrest; poachers’ snares set for other animals such as antelope; respiratory and other diseases probably transmitted by humans; and poaching for the gorilla infant trade.

The only type of gorilla that is known to be increasing is the mountain gorilla. Between 1989 and 2003, the Virunga mountain gorilla population increased by 17% and nearly all that increase occurred within the sector of the park protected by The Fossey Fund. This is astounding, particularly given that civil wars occurred in both Rwanda and Congo during portions of this time period. This increase is attributed to the intense conservation efforts of the national park authorities in Rwanda, Congo and Uganda as well as the Dian Fossey Gorilla Fund International and its partners.


Since Dian Fossey’s time, gorilla conservationists have sometimes had to care for infant gorillas confiscated from poachers. But these young gorillas are physically and emotionally fragile, and have usually suffered from extremely traumatic conditions. It is assumed that at least four gorillas have been killed to obtain an infant: certainly the mother, likely the silverback and probably other family members coming to protect their kin.

The Fossey Fund cares for many young orphaned gorillas rescued from poachers or armed conflict, with the goal of one day returning them to the wild. Raising the gorillas for release will provide genetic diversity critical for a healthy species.

A new state-of-the-art facility was just opened in Kasugho, Democratic Republic of the Congo called GRACE (Gorilla Rehabilitation and Conservation Education center). This Fossey Fund facility will be a haven for up to 30 rescued Grauer’s gorillas, where they will live in a group similar to those in the wild and ultimately, we hope, will be released into the wild as their own family. The center is on land donated by the local community. The gorillas will have access to 20 hectares (49 acres) of forest when construction is complete.

The first four gorilla residents arrived at GRACE on April 27th by UN helicopter. The infants had been living in a temporary facility in Goma with their human care staff who must take on the role of both silverback and mother for the youngsters. The gorillas instantaneously seemed at ease, after a stressful travel day, when they were allowed to roam their new forest home. They started eating forest foods that they hadn’t seen since they were taken from the forest and even started building nests. Six more orphaned gorillas will arrive at GRACE in mid-June.

The GRACE Center will have an impact beyond the rehabilitation of rescued gorillas. Studies have shown that gorilla rehabilitation centers in other areas have helped to discourage the illegal trade in live gorilla infants. Authorities are quicker to confiscate poaching victims if they know there is a place that will receive them. In addition, the center will welcome researchers and students, and house a conservation education and public information program designed by the local university, the Tayna Center for Conservation Biology (TCCB).

The Fossey Fund operates GRACE in collaboration with the Congolese conservation authority (ICCN) with assistance and support from the Pan African Sanctuary Alliance, TCCB, the Disney Worldwide Conservation Fund and animal experts from Disney’s Animal Programs.


Helping people in Africa thrive helps endangered gorillas survive, too.

Poverty reduction, health promotion and conservation education are irrevocably linked to environmental protection. The Dian Fossey Gorilla Fund International has developed programs to help people in Rwanda and the Democratic Republic of Congo where we protect gorillas, to address many of these issues: alleviating extreme poverty; developing public-private partnerships; increasing access to essential medicines; combating disease through intestinal parasite treatment and educational prevention; empowering women; helping children go to school; reducing child mortality; improving maternal health; assisting in environmental stability and reversing loss of environmental resources. The Fossey Fund’s people programs have four major goals:

To provide a healthy environment for local people living around protected areas.
To enhance environmental protection and conservation of endangered species living in Volcanoes National Park.
To improve awareness and understanding of the role of community projects in successful natural resource conservation.
To ensure sustainability of community projects and community ownership of the projects through capacity building and local involvement.

Copyright 2010 The Dian Fossey Gorilla Fund International. All rights reserved.




Basic information on Gorillas

Mountain Gorillas

Dian Fossey & Karisoke Research Center

Gorilla Research & Conservation

Gorilla Rehabilitation & GRACE

Helping people helps gorillas

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