Mountain Gorillas are the largest existing species among primates family unit. They are ground-dwelling, mainly herbivorous apes that inhabit the forests of Uganda, Rwanda and DR Congo. Gorillas are divided into two species and either four or five subspecies. The Deoxyribonucleic acid (DNA) of gorillas is highly similar to that of a human, from 95-99% basing on what is counted, and they are the next closest living relatives to humans after the two chimpanzee species. Gorillas’ natural habitats cover tropical or subtropical forests in Africa. The mountain gorillas dwell in the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft).
In the midst of the animals, there are few that have sparked the imagination of man as much as the gorilla, the biggest of the living primates and the last member of the ape family known to science. Most gorillas live in remote regions in various dense forests in tropical Africa, and only in the last 30 years have scientists learned details of their life in the wild. A sequence of eight volcanoes known as the Virunga Volcanoes runs through a western section of the Rift Valley, forming part of the border between Uganda, Democratic Republic of Congo and Rwanda. These stunning mountains and the nearby Bwindi Impenetrable National Park in Uganda are the last refuges of the most endangered of the gorilla subspecies, the Mountain Gorillas. Only about 880 of these individuals remain today in the whole world.
Gorilla Evolution and Classification
To the mountain gorillas, their closest relatives are chimpanzees and humans, all of the Hominidae (chimpanzees, gorillas, humans, and orangutans) having moved away from a common ancestor about 7 million years ago. Human being genes differ only 1.6% on average from their corresponding gorilla genes in their order, but there is further difference in how many copies each gene has.
Not until in recent times, there was well thought-out to be a single gorilla species, with three subspecies: the western lowland gorilla, the eastern lowland gorilla and the mountain gorilla. There is now a common agreement that there are two species with two subspecies each. Of recent, it has been asserted that a third subspecies exists in one of the species. The separate species and subspecies developed from a single type of gorilla during the Ice Age, when their forest habitats disappeared and became isolated from each other.
Primate experts keep on exploring the relationships between various gorilla populations. The species and subspecies listed here are the ones upon which most scientists agree. Mountain Gorilla (Gorilla beringei beringei), Genus Gorilla, Western Gorilla , Western Lowland Gorilla, Cross River Gorilla, Eastern Gorilla (Gorilla beringei), and Eastern Lowland Gorilla (Gorilla beringei graueri). Of the above, the Mountain Gorillas are the most harshly endangered, with an estimated population of about 880 left in the wild and none in zoos.
Where do Gorillas live?
The Gorilla physical characteristics
Gorillas move around by knuckle-walking, even though they sometimes stride bipedally for short distances while carrying food or in self-protective situations. Adult males, (silverbacks) range in height 1.65–1.75 metres (5 ft 5 in–5 ft 9 in), and in weight 140–200 kg (310–440 lb). Adult females are often half the size of a silverback, averaging about 1.4 metres (4 ft 7 in) tall and 100 kg (220 lb). From time to time, a silverback of over 1.8 metres and 230 kg has been recorded in the wild. Obese gorillas in captivity have reached a weight of 270 kg. The Mountain gorilla is the darkest of all the gorilla types. The Mountain gorillas also have the thickest hair. The Western Lowland Gorilla can be brown or grayish with a reddish forehead. In addition, gorillas that live in lowland forests are more slender and agile than the more colossal Mountain Gorillas.
Approximately all gorillas share the same blood type and similar to human beings, have individual finger prints. Their eye color is dark brown, framed by a black ring around the iris. The silverback gorilla is huge, with a short, thick trunk and broad chest and shoulders. The gorilla eyes and ears are dwarfed by the large head and hairless, shiny black muzzle. Older males develop a crown of muscle and hair that makes the head look even longer. Like all great apes, gorillas have arms that are longer than their legs and have a tendency of walking on all four limbs at certain times – a movement that is called knuckle walking.
Mountain Gorillas Habitats
Mountain Gorillas primarily inhabit tropical forests. Tropical forests are described as having little variation in temperature (around 23°C) and length of daylight (around 12 hours). On the other hand, rainfall varies significantly in the tropics and is a major factor as to the type of vegetation that grows in an area. The most serious threat to gorillas is habitation loss. The rich volcanic soil of the Virungas is as highly treasured as farming land. In Uganda, Rwanda and Congo, a regional conservation program emphasizing the significance of preserving the virgin forest watershed and the need to habituate some groups of mountain gorillas for tourist visits has helped reduce encroachment. Gorillas rely on the moist vegetation produced by the high clamminess and rainfall of the tropical forest.
Mountain Gorillas construct nests for daytime and night use. Day nests tend to be simple aggregations of branches and leaves on the ground while night nests are more elaborate constructions in trees. The nests may be 2 to 5 feet (0.61 to 1.5 m) in diameter and are constructed by individuals. The young nest with the mother but constructs nests after three years of age, initially close to that of their mother. Gorilla nests are distributed arbitrarily and use of tree species for site and construction appears to be opportunistic. Nest building by great apes is now considered to be not just animal architecture but as an important instance of tool use.
Mountain Gorilla Distribution
The Mountain gorillas (Gorilla beringei beringei) are one of the two subspecies of the eastern gorilla. There are two populations. One is found in the Virunga volcanic mountains of Central Africa, within three National Parks: Mgahinga, in south-west Uganda; Volcanoes National Park in north-west Rwanda and Virunga in the eastern Democratic Republic of Congo (DRC). The other is found in Bwindi Impenetrable Forest National Park in Uganda. As of November 2012, the estimated total number of mountain gorillas is 880, with half the number being found in uganda
Mountain Gorilla Behaviors
Mountain gorillas are timid and held in reserve rather than aggressive and treacherous. The gorillas to a larger extent look for no danger unless harassed but will bravely safeguard its family group if in danger. Family groups are supportive and may have up to 30 members, but even if smaller, the group normally consists of at least one older male 9Silverback), one or more females and a few young ones.
Mountain Gorillas have strong attachments to members of their own group and even when groups meet and intermingle and then afterwards part, each animal tends to remain with its own family unit. A silverback named for the silvery gray hairs on its back, over and over again leads each group, serving as its chief guard and protector. Mountain Gorillas persistently roam through their home ranges of 10 to 15 square miles, feeding and resting in the course of the day. For the reason that gorillas are wandering, they build fresh nests each day at sundown using bent branches in a tree or of grasses on the ground.
Mountain Gorillas shout, grab underbrush and possessions and put in their mouths, stand erect on their posterior legs, tear up and throw plants, drum on the chest with hands or fists, stamp their feet, strike the ground with the palms of their hands and gallop in a mock attack on all fours.
The Gorilla Diet and Eating Habits
Gorillas are herbivores and eat leaves, shoots, roots, vines and fruits. Although they eat a variety of plants, favorites include wild celery, bamboo, thistles, and stinging nettles, bed-straw and certain fruit. These plants seem to provide sufficient moisture so that they do not need water. An adult male gorilla may consume more than 18 kg (40 lb) of vegetation per day. Gorillas rarely drink in the wild because they consume succulent vegetation that is comprised of almost half water as well as morning dew. Their methods of collecting food are:-
1. Gorillas can use their enormous power to break apart vegetation. An adult male for example can cut up apart a whole banana tree to get to the interior tender pith. 2. Gorillas are very selective foragers. They usually only eat parts of vegetation. For example they may eat only the leaves, pith, stalk, or roots of a particular plant. They use their agile lips and hand dexterity to manipulate the vegetation for the particular portion they want to consume.
3. Gorillas do not over exploit an area for food. They crop the vegetation in a manner that allows for quick replenishment to occur.
4. Gorillas have been documented using the hair on the back of their hands to absorb water and then sucking it.
The Gorilla Reproduction and Parenting
Mountain Gorilla infants are weak at birth and weigh about 3-4 pounds. They learn to make slow progress at about 2 months and are walking by the time they are around 8 or 9 months. Mother gorillas take care of their babies for about 3 years, following which the young become more independent. Mountain Gorillas have an unhurried pace of reproduction. The mating time for gorillas is possible throughout the year with a pregnancy gestation of 8.5 months. Females give birth for the first time at about age 10 and will have more offspring every three or four years. A male begins to breed between 12 and 15 years, when he is in charge of his own group. Able to conceive for only about three days each month, the female produces a single young.
The newborn gorillas are weak and tiny and their movements are as awkward as those of human infants, but their development is roughly twice as fast. At 3 or 4 months, the gorilla infant can sit upright and can stand with support soon after. It suckles regularly for about a year and is gradually weaned at about three and a half years, when it becomes more independent.
Mother gorilla with infant.
Gorilla infants are susceptible and defendant and thus mothers, their primary caregivers, are vital to their continued existence. Gorilla mothers invest years caring for their children. Male gorillas are not active in caring for the young ones but they do play a role in socializing them as they tend to associate with older infants and juveniles. The silverback has a principally supportive relationship with the infants in his group. He will protect them from intragroup antagonism. Infants remain in contact with their mothers for the first five months and mothers seek close proximity with the silverback for protection. Infants will suckle at least once per hour and will sleep with their mothers in the same nest. Infants begin to break contact with their mothers after five months but only for brief period each time. By 12 months, infants venture up to five meters (16.4 ft) from their mothers. At around 18–21 months, the distance between mother and offspring increases and they regularly spend time away from each other. In addition, nursing decreases to once every two hours. Infants spend only half of their time with their mothers by 30 months. Gorillas enter their juvenile period at their third year and this lasts until their sixth year. At this time, gorillas are weaned and they sleep in a separate nest from their mothers. After their offspring are weaned, females begin to ovulate and soon become pregnant. Conflicts in weaning between mother and offspring are minimized as the young has many play partners including the silverback. Females mature at 10–12 years (earlier in captivity); males at 11–13 years. Lifespan is between 30–50 years, although there have been exceptions. For example the Dallas Zoo’s Jenny lived to the age of 55.
A female’s first ovulatory cycle occurs when she is six years of age and is followed by a two year long period of adolescent infertility. The estrous cycle last 30–33 days with outward ovulation signs subtle compared to that of chimpanzees. The gestation period lasts 8.5 months. Female mountain gorillas first give birth at 10 years of age and have four year inter-birth intervals. Males can be fertile before reaching adulthood. Gorillas mate year round. Females incite copulation by pursing their lips and slowly approaching a male while establishing prolonged eye contact. If the male does not respond, then she will try to attract his attention by reaching towards him or slapping the ground. In multi-male groups, solicitation indicates female preference. However females can be coerced to mate with multiple males. Males incite copulation by approaching a female and displaying at her or touching her and giving a “train grunt”. Recently, gorillas have been observed engaging in face-to-face sex, a trait that was once considered unique to humans.
The Gorilla Communication
Twenty-five distinct vocalizations are recognized, many of which are used primarily for group communication inside impenetrable vegetation. Sounds classified as grunts and barks are heard most regularly while traveling, and indicate the whereabouts of individual group members. They may also be used during social interactions when discipline is required. Screams and roars signal alarm or warning, and are produced most often by silverbacks. Deep, rumbling belches suggest contentment and are heard frequently during feeding and resting periods. They are the most common form of intra-group communication. Severe aggression is rare in stable groups, but when two mountain gorilla groups meet, the two silverbacks can sometimes engage in a fight to the death, using their canines to cause deep, gaping injuries. The entire sequence has nine steps: (1) progressively quickening hooting, (2) symbolic feeding, (3) rising bipedally, (4) throwing vegetation, (5) chest-beating with cupped hands, (6) one leg kick, (7) sideways running, two-legged to four-legged, (8) slapping and tearing vegetation, and (9) thumping the ground with palms to end display.
Mountain Gorillas are considered highly gifted in intellect. A few individuals in captivity have been taught a subset of sign language. Similar to the other great apes, gorillas can laugh, grieve, have “rich emotional lives,” build up strong family bonds, can make and use tools, and can think about the past and future. Several researchers believe that gorillas have spiritual feelings or religious sentiments. Gorillas have been shown to have cultures in different areas spinning around different methods of food preparation, and gorillas will demonstrate individual color preferences.
The Mountain Gorilla Population
The mountain gorilla is estimated to have several small protected family groups living around the Bwindi area (about 400 individuals) and the Virunga volcanoes (about 480 individuals). Even though many mountain gorillas live in protected parks, disease outbreaks, environmental catastrophic events, and genetic isolation could extensively reduce their population. Conservation International and the primate specialist division of the World Conservation Union (IUCN) have classified this species as one of the 25 most endangered primates.
On the other hand, the number of mountain gorillas, which are a critically endangered species, has increased by more than 26% in regions in Eastern Africa, according to a recent survey by the World Wildlife Fund says it counted 880 mountain gorillas in the Virunga Massif region that spans the Democratic Republic of the Congo, Rwanda and Uganda. And this increase brings the world population to 880 mountain gorillas. The second population of mountain gorillas is found in a mountainous region referred to as the Virungas, which includes Mgahinga Gorilla National Park (Uganda), Volcanoes National Park (Rwanda) and Virunga National Park (Democratic Republic of Congo).
The Gorilla Social Structure
Mountain Gorillas inhabit in groups called troops. Troops tend to be made of one adult male or silverback, numerous adult females, and their offspring. However, multi-male troops also exist. Silverbacks are typically more than 12 years of age and named for the distinctive patch of silver hair on his back. A silverback gorilla has large canine teeth that come with maturity. Both males and females tend to emigrate from their biological groups. Dispersal from natal troops is more common in females than males for mountain gorillas. Female mountain gorillas and western lowland gorillas also commonly transfer to a second new group. Mature males tend to also leave their groups and establish their own troops by attracting emigrating females. However, male mountain gorillas sometimes stay in their natal troop and become subordinate to the silverback. They may gain the opportunity to mate with new females or become dominant if the silverback dies. This behavior has not been observed in eastern lowland gorillas. In a single male group, when the silverback dies, the females and their offspring disperse and find a new troop. Without a silverback to protect them, the infants will likely fall victim to infanticide. Joining a new group is likely to be a tactic against this. However while gorilla troops usually disband after the silverback dies, female eastern lowlands gorillas and their offspring have been recorded staying together until a new silverback transfers into the group. This likely serves to decrease chance of being attacked by leopards. All male troops have also been recorded.
The silverback is the center of the troop’s attention, making all the decisions, mediating conflicts, determining the movements of the group, leading the others to feeding sites and taking responsibility for the safety and well-being of the troop. Younger males subordinate to the silverback, known as blackbucks, may serve as backup protection. Black backs are males between 8 and 12 years of age and lack the silver back hair. The bond a silverback has with his females forms the core of gorilla social life. Bonds between them are maintained by grooming and close proximity. Having strong relationships with males is important for females as males give them mating opportunities and protection from predators and infanticide outside males. However aggressive behaviors between males and females are common although they rarely lead to serious injury. Relationships between females may vary. Maternally related females in a troop associate closely and tend to have friendly interactions. Otherwise, females usually have little friendly interactions and commonly act aggressive towards each other. Aggressive interactions between females tend to be centered on social access to males with males intervening in fights between females. Male gorillas have weak social bonds, particularly in multi-male groups with apparent dominance hierarchies and strong competition for mates. However, males in all-male groups tend to have friendly interactions and socialize through play, grooming and close proximity and occasionally they even engage in homosexual interactions.
Mountain Gorilla Endangerments
Mountain Gorillas are endangered by habitat loss due to increasing human populations, poaching for the bush meat trade and diseases like Ebola. Species that live in higher elevations, like mountain gorillas, are also affected by climate change, which has the potential to impact gorillas directly by altering their habitat and indirectly by affecting agriculture yields in nearby communities, which in turn puts more pressure on remaining habitation.
The gorilla’s only known enemies are leopards and humans. Crocodiles are potentially perilous to lowland gorillas. In western Africa, gorillas are commonly hunted for meat or in revenge for crop looting, but in East Africa they have been the victims of traps set for antelopes and other animals. Poachers also obliterate the entire family groups in their attempts to capture infant gorillas for zoos, while others are killed to sell their heads and hands as trophies.
Fast Fact about Mountain Gorillas
– There are only 880 mountain gorillas left in the world.
– Humans and gorillas are 98% genetically indistinguishable or alike.
– Similar to humans, gorillas have unique individual fingerprints!
– Gorillas rarely attack humans. But in an encounter a person should stay still and refrain from staring or pointing at the gorilla.
– Gorillas are prone to a variety of parasites and diseases, mainly to pneumonia during the long, cold wet seasons.
– Male silverback gorillas can weigh 50-100 pounds or more and are about 10 times stronger than the biggest American football players.
– When the group is attacked by humans, leopards, or other gorillas, the silverback will protect them even at the cost of his own life.
– Found in these Heartlands: Virunga
– Scientific Name: Gorilla beringei beringei
– Size: Males: Up to 6 feet tall, standing. Females: Up to 5 feet tall.
– Weight: Males: 350 pounds. Females: 215 pounds.
– Lifespan: 40-50 years
– Habitat: Dense forest, rain forest
– Diet: Herbivorous (vegetarian)
– Gestation: About 8 1/2 months
Predators: Predominantly humans. Occasionally leopards.