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Species of Primates of the Albertine Rift Valley

One of the greatest interests for visiting Uganda, Rwanda, Congo and Burundi is the presence of the primates and related tourist activities. Destination Jungle is offering primates tours within the Albertine Rift Valley region.

There are about 13 species of primates found in the Albertine Rift Valley, including the great apes and several monkeys, some of which are nocturnal mammals. We list below the most common as well as the most peculiar.

Mountain Gorillas (Gorilla gorilla beringei)

The Mountain Gorilla is one of the three species of Great Apes found in the Albertine Rift valley, the other two being the Eastern low land gorillas and the chimpanzees. This much endangered species is only found in two montane forests: the Virungas shared between Rwanda, Congo and Uganda and Bwindi Impenetrable in Uganda. Most are found on the slopes of three of the dormant Virunga volcanoes: Karisimbi, Mikeno, and Visoke. The total number of mountain gorillas is about 750 individuals remaining.

The Mountain Gorilla has thicker and longer fur than that of other Gorilla species and this enables them to live in colder temperatures. Gorillas can be identified by nose prints unique to each individual. Males usually weigh twice as much as the females. Adult males have more pronounced bony crests on the top and back of their skulls, giving their heads a more conical shape. Adult males are called silverbacks because a saddle of gray or silver-colored hair develops on their backs with age. The hair on their backs is shorter than on most other body parts, and their arm hair is especially long. Like all great apes other than humans, its arms are longer than its legs. It moves by knuckle-walking like the common chimpanzee, supporting its weight on the backs of its curved fingers rather than its palms.

The Mountain Gorilla is highly social, and lives in relatively stable, cohesive groups held together by long-term bonds between adult males and females, these groups are non territorial; the silverback generally defends his group rather than his territory. The dominant silverback determines the movements of the group, leading it to appropriate feeding sites throughout the year. Each gorilla builds a nest from surrounding vegetation to sleep in, constructing a new one every evening. Only infants sleep in the same nest as their mothers. They leave their sleeping sites when the sun rises at around 6 am, except when it is cold and overcast; then they often stay longer in their nests.

The low reproduction rate of the gorillas is one of the reasons why they are an endangered species. In a 40-50 year lifetime, a female might have only 2 to 6 babies. A male reaches sexual maturity between 10 and 12 years.

Tourist activities to see the mountain gorillas have always being object of discussion, as the need to receive revenue from tourists must consider the aspects of conservation of the species.

In 2010 there are 7 families of gorillas open to gorilla tracking in Bwindi forest and other 8 families in Volcanoes National park in Rwanda. Destination Jungle organizes the gorilla trekking program and more comprehensive Primates tours packages.

Eastern Lowland gorillas

  • English – Eastern Lowland Gorilla, Grauer’s Gorilla
  • French – Gorille de plaine de l’Est, Gorille de Grauer
  • German – Grauer-Gorilla
  • Spanish - Gorila de Grauer

The Eastern Lowland Gorilla (Gorilla beringei graueri) is a subspecies of gorillas, together with the endangered mountain gorillas and the Western lowland gorillas (Gorilla gorilla gorilla). The western lowland gorillas are not considered endangered species, being present in African countries like Congo-Brazzaville, Central African Republic, Equatorial Guinea, Cameroon, Gabon and Congo.

The Eastern lowland gorillas are endangered and they are found specifically in Kahuzi Biega National Park and Maiko National Park in the Democratic Republic of Congo. They live in heavy rain forests, and it is difficult for scientists to accurately estimate how many survive today. The Eastern Gorilla tends to be larger in size than the Western. Differences between the two species include: longer, blacker hair for the Eastern; the head hair tends not to have red-chestnut tones as is usually the case with adult Western males.

Eastern Lowland Gorillas tend to be sociable and very peaceful, living in groups of 5 to 30. A group usually consists of one silverback and few subdominant males. Silverbacks are the strong, dominant troop leader’s .They are in charge of leading the group to food and protecting the group from danger. Males will slowly begin to leave their original group when they reach maturity, usually traveling with a group of other males for a few years before being able to attract females to form a new group.

The leader organizes troop activities like eating, nesting in leaves, and moving about the group's home range. They eat roots, shoots, fruit, wild celery, and tree bark and pulp, as well as ants, termites and other insects. When fruit is scarce, Eastern Lowland Gorillas travel less and increase their consumption of herbaceous vegetation. They follow seasonal eating behavior.

Female gorillas give birth to one infant after a pregnancy of nearly nine months. Unlike their powerful parents, newborns are tiny—weighing four pounds (two kilograms)—and able only to cling to their mothers' fur. These infants ride on their mothers' backs from the age of four months through the first two or three. Young gorillas, from three to six years old, remind human observers of children. Much of their day is spent in play, climbing trees, chasing one another, and swinging from branches.

In the wild, these primates are under siege. Forest loss is a twofold threat; it destroys gorilla habitat and brings hungry people who hunt gorillas for bush meat. Farming, grazing, and expanding human settlements are also shrinking the lowland gorillas’ space.

The Eastern Lowland Gorilla occurs only in eastern DRC, between the Lualaba river and the Burundi-Rwanda-Uganda border. Its distribution is limited to an area of about 90,000 km², within which it is thought to occupy an estimated 21,600 km² in five regions.

The trekking to see the Eastern lowland gorillas is open in the protected area of Kahuzi Biega National Park. In 2010 there are three habituated families, Chimanuka, Mankoto and Mugaruka. With ten families of gorillas remaining in the park area, the estimated number of gorillas today is 140 individuals only. A previous survey conducted in 1992 was showing the presence of 25 families with a total number of 284 individuals. The political turmoil which followed during the 90th and till recent time has affected much the conservation of the species.

The Chimpanzees

Eastern chimpanzee (Pan Troglodytes Schweinfurthii)

The chimpanzees are our closest living relatives, sharing more than 98 per cent of our genetic blueprint. Humans and chimps are also thought to share a common ancestor who lived some four to eight million years ago. The chimpanzees are distinguished in two categories, the bonobo (Pan Paniscus) of the low land forests of Congo and the more common chimpanzee Pan Troglodytes.

Although chimpanzees normally walk on all fours (knuckle-walking), they can stand and walk upright. By swinging from branch to branch they can also move quite efficiently in the trees, where they do most of their eating. Chimpanzees usually sleep in the trees as well, they are generally fruit and plant eaters, but they also consume insects, eggs, and meat.

Chimpanzees are one of the few animal species that employ tools. They shape and use sticks to retrieve insects from their nests or dig grubs out of logs. They also use stones to smash open tasty nuts and employ leaves as sponges to soak up drinking water. Females can give birth at any time of year, typically to a single infant that clings to its mother's fur and later rides on her back until the age of two. Females reach reproductive age at 13, while males are not considered adults until they are 16 years old

Like other families of primates, the chimpanzees are more and more endangered. While in the 1960s they were over one million distributed among 21 countries, today we estimate there remain only 250.000 chimpanzees. Only in Uganda from a general survey of 2002 the estimated number of chimpanzees is 5000 individuals, distributed among different forest: 600 in Budongo, 1420 in Kibale, 450 between Kalinzu and Maramagambo, 210 in Bwindi. In Rwanda most of the chimpanzees are found in Nyungwe Forest with over 1000 individuals. Chimpanzees are also in Kahuzi Biega National Park, but not habituated, while small numbers are also seen regularly in Burundi in Kibira Forest and Bururi forest near Bururi.

Golden Monkeys

The golden monkey (Cercopithecus mitis kandti) is an endemic primate of the Albertine Rift Valley. Golden monkeys live in groups between 20-80 individuals usually led by one adult male. They eat about 20 -30 plant species mainly leaves, fruits and invertebrates, but their main preference is bamboo. They weigh about 5 to 12 kg; the males have a reddish color on their back and on the dorsal part of their sides as well as some grizzled darker patches. Females are lighter in color and have less grizzled brown patches.

Little was known until recent decades about this primate, which was originally found in Gishwati forest but brought to extinction with the intensive deforestation. Today the only remaining troops of golden monkeys are found in Volcanoes National Park in Rwanda and in Mgahinga National Park in Uganda bordering Rwanda. With cooperation between ORTPN and Dian Fossey Gorilla Fund International (DGFIFI), two groups of golden monkeys have been habituated for tourist activities and this project will support the conservation of the species.

Bush Baby

The African name for a bushbaby is "komba". They are one of the smallest primates and their scientific name is "lesser bush baby". Bush babies are found throughout East Africa, as well as in woodlands and bushlands in sub-Saharan Africa. They generally do not inhabit areas above altitudes of 6,500 feet. Sometimes they construct nests in the forks of branches, but these are not as commonly used as are natural holes. Bush babies prefer trees with little grass around them, probably as a precaution against wild fires. The bush babies are about 23 to 25 centimeters long and 7 to 8 inches long. They have large round eyes for good night vision and bat like ears that enable them to track insect prey in the dark, a long curved claw on the second toe and are about the size of a rabbit. Their coat is gray with yellow-tinged under parts. Bushbabies weight about 5 to 10 ounces with a long tail. Bushbabies eat fruits, nuts, vegetables, snails, beetles, ants, termites, birds, butterflies and moths. They also feed on the gum of trees. Their enemies are eagles, owls, genets and large snakes. They can live up to 14 years. These can be found in Semiliki National Park, Murchison Falls National Park, Kidepo Valley National Park and Lake Mburo National Park, where they are regular visitors at Mihingo Lodge.

Patas Monkey

The Patas Monkey (Erythrocebus patas) grows to 85 cm in length, excluding the tail, which measures 75 cm. The Patas monkey has a russet-red coat, gray chin whiskers and white military mustache and walk on their fingers, not on their palms. It has long legs, narrow body and prominent rib cage and is probably the fastest primate on earth; its long legs give it a tremendous loping stride. Adult males are considerably larger than adult females. The Patas Monkey lives in multi-female groups of up to 60 individuals, and avoids dense woodlands living in more open savanna and semi-deserts. The patas can climb small trees when alarmed but usually rely on their speed on the ground to escape from danger.

The Patas Monkeys are omnivorous, but can apparently feed on either animal or vegetable food alone. They search on the ground for insects, grubs, buds, gum, seeds, leaves, fruits and tubers, and young birds and eggs, a diet more characteristic of small primates.

Patas monkeys can be found in Kidepo Valley National Park and Murchison Falls National Park in Uganda.

L’Hoest Monkey

The L’hoest monkey (Cercopithecus lhoesti) commonly found in Uganda, Rwanda and DRC Congo is a very dark, richly colored animal with a pure white chin ruff framing on the face and white patches under their eyes, it also known as the Mountain Monkey. The L’hoest Monkey can be found in a range of different kinds of forested areas, including gallery forest, mature lowland rain forest, wooded savannah at mountain slopes, and forest borders. The males are larger than the females and have bright mauve testes.

The L’hoest moneys live in groups of about 17 individuals dominated by females with one or two adult males. They eat leaves; seeds, flowers, fruits and insects, occasionally will eat bird eggs, lizards and even small birds. They move mainly on the forest floor, but flee up into the trees if threatened.

There is a decrease in the L’hoest monkeys in the wild because of deforestation of their habitat for farming, hunting for bush meat mainly by the use of snares by hunters. The fact that they are also found in areas of warfare and intense human conflict, this too becomes a threat to them. This means that the L’hoest monkey is facing a high risk of extinction in the wild.

Most of the East African populations occur in the montane areas of western Uganda, but the species is also found in Kibale, Kalinzu and Kayonza which are medium altitude forests. In these areas the species prefers the thick regenerating growth in felled compartments. The bamboo forest zone seems to define the upper altitudinal limits of the range. L’Hoest is also found in Nyungwe Forest in Rwanda and Kahuzi Biega National Park in Congo.

Black-and-White Colobus Monkeys (Colobus guereza)

The word Colobus comes from Greek “ekolobose” and is so named because its thumb is a stump. Colobus are large monkeys with a head and body length longer at 78cm. Fur is black with white or greyish whiskers and epaulettes and a white tail. Thumb is absent or greatly reduced. Newborn infants are pure white, obtaining their adult markings by 3 – 4 months. Colobus monkeys live in African forests in groups of 3 – 15 individuals within a well defined territory, while the red colobus live in larger groups with many males. They are arboreal and seldom come to the ground, except occasionally to pick up fallen fruit.
Their diet consists mainly of both young and mature leaves, but they also eat fruit, flowers and woody twigs.

Colobus monkeys can be found in Bwindi Impenetrable National park, Semiliki National park, Kibale forest National park all in Uganda and then Nyungwe Forest National park in Rwanda with a semi-habituated troop of 400 species, resident in the forest.