What you should know about gorillas
Gorillas are some of the most powerful and striking animals, not only for their size and force, but also for their gentle human like behavior. They play a crucial role in local biodiversity, roaming through large territories and helping, for example, to spread the seeds of the fruit they consume
For a long time the image most people had of a gorilla encounter included chest pounding, roaring, charging and big, bared teeth. Studies on mountains gorillas however reveal a very different picture. Mountain Gorillas are peaceful, gentle, social and mainly vegetarian creatures. The occasional ferocious-looking, impressive displays are generally from a male gorilla protecting his family group from a threat. Gorillas, especially males, have a wide range of vocal and physical communications. Silverbacks can roar, scream and bark to deter predators or competitors. Mountain Gorillas stand on their legs and beat their large chests, which contain air sacks, to produce an intimidating thudding sound. Mountain Gorillas may even charge at people or gorillas they see as threatening, striking the ground with their fists in a display of aggression.
Intelligent, charismatic, and endangered
Gorillas are our closest living relatives after chimpanzees and bonobos.
The two gorilla species live in equatorial Africa, separated by about 900km of Congo Basin forest. Each has a lowland and upland subspecies.
- Western lowland gorilla (G. g. gorilla),
- Cross River gorilla (G. g. diehli)
- Mountain gorilla (G. b. beringei)
- Eastern lowland or Grauer’s gorilla (G. b. graueri)
All four subspecies are either Endangered or Critically Endangered, threatened by hunting for bushmeat, habitat loss, wildlife trade, and infectious diseases.
Gorillas have a well-developed social structure, forming stable family groups in which the dominant male keeps his position for years.
Group size is usually 5-10 individuals, but can vary from 2 to over 50 members. According to group size, habitat quality and food availability, a group’s home range may vary from 5 to over 30km², with frequent overlap between group ranges.
Primates, in general, are very social animals, and mountain gorillas are no exception. They are highly social and live in relatively stable, cohesive groups held together by long-term bonds between adult male mountain gorillas and Female Mountain gorillas though relationships among females are relatively weak. Males leave when they are about 11 years old, and often the separation process is slow: they spend more and more time on the edge of the group until they leave altogether. They may travel alone or with an all-male group for 2–5 years before they can attract females to join them and form a new group.
Gorilla Group sizes vary from five to thirty, with an average of ten individuals. A typical group contains: one dominant silverback, who is the group’s undisputed leader; another subordinate silverback (usually a younger brother, half-brother, or even an adult son of the dominant silverback); one or two black backs, who act as sentries; three to four sexually mature females, who are ordinarily bonded to the dominant silverback for life; and from three to six juveniles and infants. Female gorillas typically emigrate when they are about 8 years old, either transferring directly to an established group or beginning a new one with a lone male. Females often transfer to a new group several times before they settle down with a certain silverback male.
Females become sexually mature at 7-8 years old, but do not start to breed until several years later. Males mature later than females, with few breeding before the age of 15 years.
High infant mortality, a long gestation (8.5 months), a tendency to single births, and a prolonged period of maternal care mean that, on average, only one baby is reared in a 4-6 year period. Females generally give birth to only three or four surviving young during their reproductive life.
The mortality rate for gorillas less than one year old is high, but for adults the rate is only 5%. In the wild, they might live to be 40 years old. In the United States, a captive gorilla was reported to have lived to the age of 54.
They form groups that are non-territorial; the silverback generally defends his group rather than his territory. The male mountain gorilla is a highly intelligent and gentle creature despite a ferocious reputation; the Mountain Gorilla only makes use of his incredible strength and displays dominance, when it comes to defending the family or breeding rights.
The dominant silverback mediates conflicts within the group and protects it from external threats. When the group is attacked by humans, leopards, or other gorillas, the silverback will protect them even at the cost of his own life. He is always the center of attention during rest sessions, and young animals frequently stay close to him and include him in their games. If a mother dies or leaves the group, the silverback is usually the one who looks after her abandoned offspring, even allowing them to sleep in his nest. Experienced silverbacks are capable of removing poachers’ snares from the hands or feet of their group members.
Protection and security
Since gorillas are highly social animals, they try to defend one another when danger threatens, when the group is attacked by humans, leopards, or other gorillas, the silverback will protect them even at the cost of his own life. For example, poachers trying to get a baby gorilla often have to kill the dominant silverback and mother first. The death of one animal also has an effect on many others. In particular, when the dominant silverback of a family group dies or is killed by disease, accident, or poachers, the family group may be severely disrupted. The large family group may split into two or more smaller groups, unless there is an accepted male descendant capable of taking over his position. The group will either split up or adopt an unrelated male. When a new silverback joins the family group and when a new silverback takes control of a family group, he may kill all of the infants of the dead silverback; this practice of infanticide is seen in various animals like monkeys, prairie dogs, and lions. It is an effective reproductive strategy in that the new male conceives progeny that perpetuate his genes. In stable peaceful groups, there is no apparent evidence of infanticide.
Gorillas are mainly herbivorous (vegetarian) and spend almost half of the day feeding on stems, bamboo shoots, and a variety of fruits, supplemented with bark and invertebrates.
At some sites, western lowland gorillas have been known to break open termite nests and feed on the larvae.
Population & distribution of Gorillas
Many gorilla populations have declined or completely disappeared over the past few decades.
The lowland subspecies are more numerous and widespread than the upland and mountain subspecies. Mountain gorillas are the only gorillas to show an increase in numbers, but the overall population size is still very low.
- The western lowland gorilla is the most widespread, possibly numbering 100,000.
- The Cross River gorilla is currently the world’s rarest great ape, with a population of only around 250-300 restricted to a small area of highland forest on the border of Cameroon and Nigeria.
- The population of the eastern lowland gorilla has crashed in recent decades and is now under 4,000.
- The total population of mountain gorillas is around 880 individuals, split into two separate groups.
After a dramatic decline in numbers following their scientific discovery in 1902, dedicated conservation initiatives have ensured that mountain gorilla numbers are now slowly increasing.
- Common names: Mountain gorilla; Gorille de montagne (Fr); (Sp)
- Scientific name: Gorilla beringei beringei
- Location: Virunga mountains, Democratic Republic of the Congo, Rwanda and Uganda; Bwindi Impenetrable National Park
- Population: Approximately 880 individuals
- Status: Critically Endangered
Population & distribution
Mountain gorillas are found in two separate locations: the Virunga range of extinct volcanic mountains on the borders of the Democratic Republic of Congo (DRC), Rwanda and Uganda, and in the Bwindi Impenetrable National Park in Uganda. Some primatologists believe the Bwindi gorillas may be a separate subspecies.
In the 100 years since its discovery, the mountain gorilla has endured uncontrolled hunting, war, disease, destruction of its forest habitat, and capture for the illegal pet trade.
These factors led to a dramatic decline in numbers. Indeed, there were fears that the mountain gorilla would become extinct in the same century it was discovered.
Thanks to conservation efforts, the population of mountain gorillas has increased from 620 individuals in 1989 to around 880 individuals today. This number is likely to be accurate, as these animals have been intensely monitored since the 1950s.
- The Virunga population numbers 480, and lives at altitudes ranging from 2,300-4,500 m. Most of these gorillas range within the southern part of Virunga National Park, DRC, and the Volcanoes National Park (Parc National des Volcans), northern Rwanda, while a few use the Mgahinga Gorilla National Park, southwestern Uganda.
- The Bwindi population lives at elevations of 1,500- 2,300 m. A 2011 census recorded 400 individuals. Additionally, four orphaned mountain gorillas currently reside in a sanctuary in Uganda.
Gorilla Trekking is a tourist activity where tourists with the help a gorilla guide are let up in the thick forest jungles in search of a gorilla family and later spend about an hour in their presence taking punctures or just enjoying their company.
No other wildlife encounter in Africa matches the astounding experience of spending time face-to-face with wild gorillas. Gorilla Trekking takes place in a handful of far flung locations, adding a layer of exotic adventure to these gorilla safaris that is hard to match on any other itinerary. The fact that gorillas as a species are on the brink of extinction and treks are a highly restricted activity, encountering wild gorillas is considered a once-in-a-lifetime travel experience.
Popular Gorilla Safari Packages
4 Days Bwindi Gorilla Trekking Safari – from USD $1,300 per person
What to Expect on a Gorilla Trek
For a gorilla trek you need to be fairly fit, equipped for the humid, muddy conditions of a rainforest hike, and in good health – gorillas are susceptible to human illnesses but don’t have our immunities, which means a common cold can be deadly to a whole family of gorillas and you won’t be permitted to trek if you are unwell. Even in the dry season, the rainforest is a challenging environment: it’s humid, wet and muddy with some steep slopes, plenty of insects and thick vegetation. It is absolutely worth the effort to spend time with gorillas in the wild, but be prepared to exert yourself on the trek.
Your professional guide and tracker lead you into the forest’s secret paths, looking for a habituated gorilla family. Once found, you’ll approach the gorillas quietly and settle down to observe them from between 7 and 10m (22 to 32 ft) away. You’ll spend between 40 minutes and an hour with the gorillas, watching adults forage and groom each other while the babies tumble and play. You’ll be under the watchful gaze of the great silverback patriarch, whose soft brown eyes constantly sweep over his family protectively. Witnessing a gorilla express typically human gestures and emotions is a truly profound experience and one of the reasons that gorilla trekking is such a life changing encounter. In the Congo, you’ll don a face mask to protect the gorillas from human germs and have an optional fly net to keep the harmless (and stingless) but determined sweat bees from disturbing you. In Uganda and Rwanda, you’ll leave any personal items or bottled water you’re carrying with your porters and approach the gorillas with only your camera. You are not allowed to use a flash and it’s best to use a camera that doesn’t make loud clicks, whirring or other mechanical noises.