Rwanda

VOLCANO NATIONAL PARK, North-west Rwanda "In the heart of Central Africa, so high up that you shiver more than you sweat," wrote the eminent primatologist Dian Fossey, "are great, old volcanoes towering up almost 15,000 feet, and nearly covered with rich, green rainforest - the Virungas". Situated in the far northwest of Rwanda, the Parc des Volcans protects the steep slopes of this magnificent mountain range - home of the rare mountain gorilla - and the rich mosaic of montane ecosystems, which embrace evergreen and bamboo forest, open grassland, swamp and heath.

An exhilarating trek through the cultivated foothills of the Virungas offers stirring views in all directions. Then, abruptly, the trail enters the national park, immersing trekkers in the mysterious intimacy of the rainforest, alive with the calls of colourful birds and chattering of the rare golden monkey, and littered with fresh spoor of the mountains’ elusive populations of buffalo and elephant. Through gaps in the forest canopy, the magnificent peaks are glimpsed, easily accessible and among the highest in Africa, beckoning an ascent.
 
The bustling market town of Ruhengeri has a memorable setting at the base of the Virungas. On the outskirts of town, the natural bridge at Musanze - a solidified lava flow - is a fascinating relic of the volcanic activity that shaped this scenic area. Also within easy day tripping distance of Ruhengeri are the seldom visited but lovely Lakes Burera, Ruhondo and Karago. Ruhengeri offers a good selection of reasonably-priced small hotels and guest houses, including the newly renovated hotel Gorilla's Nest. Visitors could also base themselves in Gisenyi or Kigali and - with an early start - head to the Parc des Volcans and Ruhengeri as a day trip. The Mountain Gorilla (Gorilla gorilla berengei)
The Mountain Gorillas of Rwanda were made famous by Diane Fossey who dedicated her life to their future and immortalised them in her book and the film ‘Gorillas in the Mist’. There are about 700 Mountain Gorillas remaining in the world today, of which half live in the Virunga Volcanoes.

In the past poaching and habitat destruction was the main cause for concern. However with publicity, tourism and education regarding the plight of the Mountain Gorilla, the authorities have been able to halt this rapid decline. There are few animals in Africa about which so many legends circulate. The Gorilla’s enormous size, extraordinary strength and the fact that he lives in mysterious forests of luxuriant vegetation, have contributed to his mystique. A troop consists usually of a dominant male and up to five or more females and their young. It is basically a stable family with the young only leaving after they reach sexual maturity. Females join another group while young males remain solitary until they have an opportunity of forming their own troop.
 
This primate is of impressive dimensions; some males (such as Guhonda the silverback of Sabinyio Group, which you may visit), attain over six feet in height and weigh more than 440 pounds. The head is massive and the huge jaws are equipped with powerful teeth. Far from being an aggressive animal, as the legends claim, the gorilla is gentle and peaceful in its habits. It is only when threatened that he adopts an intimidating attitude in which he howls

in a most frightful way and beats his chest with his fists. Should visitors find themselves in his presence at this moment, they will be advised to assume a submissive, non-threatening attitude. Once his confidence has been restored, the gorilla goes on about his business accepting the intruder. It is estimated that there are about 170 gorillas in the Rwandan side of the park. They are very sociable animals, living in groups of three up to forty.

Being sedentary, they are continually looking for food in a living space that is comparatively restricted. They are active only during the daytime and build nests in which they pass the night. The nests built in trees are occupied by the females and young ones, while the males seem to prefer nests on the ground. Their food consists mainly of leaves, buds, tubers and sorts of wild celery from the umbelliferous family.

Rwanda Gorilla Groups:

Only the park authorities will assign your gorilla group.

• Group 13 with 7 individuals located at Sabinyio volcano
• Amohoro  group with 11 gorillas located at the Bisoke volcano    
• Umubano group with 10 individuals located between Sabinyio and Bisoke volcanoes
• Sabinyio group with 13 individuals located between Sabinyio and Bisoke volcanoes
• Susa group, 35 gorillas located on the Karisimbi volcano. Longer trekking distance
• Hirwa group, a group of 9 gorillas on the northern slope of Sabinyio volcano

Gorilla Tracking:
The trek to find gorillas can be quite short, but on most days at least an hour or two of rough hiking each way is necessary. Each visit is by permit and limited to one hour with a professional Gorilla tracker in charge who will coach you in the safety rules and body language required to come close to the Gorilla troops.At the Park Headquarters you will be assigned your group for today’s trek. Before you set off your guide will introduce himself and give you a briefing about the group that you are going to seek. You then drive the short distance to the trackers base in the foothills and meet your trackers and army rangers who will accompany you on the trek. Sticks are thoughtfully provided and extremely necessary as the terrain is slippery and sometimes the nettles take a lot of knocking back.

The trackers remain with their selected group and are familiar with that group’s movements and habits. You will notice how the Gorillas communicate with the trackers whilst you observe the group.

It is important to bear in mind that Gorilla trekking is strenuous and grubby – wear clothes that you don’t mind getting dirty, wet and muddy and that will dry out quickly and won’t chafe you as you climb. A waistcoat with lots of deep pockets is very useful as you will be asked to leave all bags, sticks and backpacks with a tracker & porters once you are within 200 metres of the group. You need pockets for spare film, disks, water bottle and any valuables or documents that you are carrying.
 
Once you are ready you head off for one of the most exhilarating and moving wildlife experiences you can have: you get so close to these giant primates, observing them observing you – their almost human movements, innate dignity and social interaction make a unique connection within each of us. The climb begins through the lush terraced farmland of the lower volcanic slopes. As the slopes become steeper and rockier, the vegetation becomes thick and tangled; the guides must use their machetes to help clear a path. Huge trees, clinging vines and undergrowth add to the challenge of swift streams and slippery red mud underfoot.
Usually at around 8,000 foot signs of the huge animals become apparent. Damage to the bamboo trees is an obvious sign as the gorillas relish the young tender shoots and break older stems to suck the sap. The smell of gorilla may waft by in the stray breeze or, if one is really near, it is strong and unmistakable.

Sounds, which can be remarkably loud crashes or dull reverberating thuds particularly when there are juveniles in the group – their hollow chest thumping makes a distinctive impression as they crash through the undergrowth around you.
 The Mountain Gorilla (Gorilla beringei beringei) is one of two subspecies of Eastern Gorillas. It is only found in the Virunga volcanic mountains of Central Africa, within three national parks: Mgahinga, in south-west Uganda; Volcanoes, in north-west Rwanda; and Virunga, in the eastern Democratic Republic of Congo.

Some claim that the Bwindi population in Uganda's Bwindi Impenetrable Forest is a third subspecies; although no formal taxonomic description has been published.

A census taken in 2003 has shown a 17% increase in population size since 1989. There are now a total of 380 gorillas in 30 social groups. However, the Mountain Gorilla continues to be considered critically endangered on the IUCN Red List of Endangered Species. It faces an extremely high risk of extinction in the wild due to habitat loss, poaching, human disease, and war.
 
The Mountain Gorilla has longer and darker hair than other gorilla species, enabling it to live at high altitudes and travel into areas where temperatures drop below freezing. It has adapted to a life on the ground more than any other non-human primate, and its feet most resemble those of humans. Gorillas can be identified by nose prints unique to each individual; researchers often use photographs and illustrations of noses for identification and monitoring.
 
The Mountain Gorilla, like all gorillas, is highly sexually dimorphic, with males usually weighing twice as much as females. Adult males also have more pronounced bony crests on the top (sagittal) and back (nuchal) of their skulls, giving their heads a more conical shape. These crests anchor the massive muscles of their large jaws. Adult females also have these crests, but they are much less pronounced.
 
Adult males are called silverbacks. When they reach sexual maturity, a saddle of gray or silver-coloured hair develops on their backs. The hair on their backs is shorter than on most other body parts, and their arm hair is especially long. Upright, males reach 1.5–1.8 m (5–6 ft) in height, with an arm span of 2.25 m (7 ft 6 in) and weigh 204–227 kg (450–500 lb).
 
The Mountain Gorilla is primarily terrestrial and quadruped. However, it will climb into fruiting trees if the branches can carry its weight, and it is capable of running bipedally up to 6 m (20 ft). Like all great apes other than humans, its arms are longer than its legs. It moves by knuckle-walking (like the Common Chimpanzee, but unlike the Bonobo and both orang-utan species), supporting its weight on the backs of its curved fingers rather than its palms.
 
The Mountain Gorilla is diurnal, most active between 6:00 a.m. and 6:00 p.m. Many of these hours are spent eating, as large quantities of food are needed to sustain its massive bulk. It forages in early morning, rests during the late morning and around midday, and in the afternoon it forages again before resting at night. 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.
 
Habitat and diet
The Mountain Gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2225 to 4267 meters (7300-14000 ft).
Most are found on the slopes of three of the dormant volcanoes: Karisimbi, Mikeno, and Visoke. The vegetation is very dense at the bottom of the mountains, becoming sparser at higher elevations, and the forests where the Mountain Gorilla lives are often cloudy, misty and cold.
 
The Mountain Gorilla is primarily an herbivore; the majority of its diet is composed of the leaves, shoots and stems (85.8%) of 142 plant species. It also feeds on bark (6.9%), roots (3.3%), flowers (2.3%), and fruit (1.7%), as well as larvae, snails and ants (0.1%). Adult males can eat up to 75 pounds of vegetation a day, while a female can eat as much as 40 pounds.
 
The home range size (the area used by one group of gorillas during one year) is influenced by availability of food sources and usually includes several vegetation zones. George Schaller identified ten distinct zones, including: the bamboo forests at 2225–2804 m (7300–9200 ft); the Hagenia forests at 2804–3353 m (9200–11000 ft); and the giant senecio zone at 3444–4267 m (11300–14000 ft). The Mountain Gorilla spends most of its time in the Hagenia forests, where gallium vines are found year-round. All parts of this vine are consumed: leaves, stems, flowers, and berries. It travels to the bamboo forests during the few months of the year fresh shoots are available, and it climbs into subalpine regions to eat the soft centres of giant senecio trees.
 
Reproduction
A newborn gorilla weighs about 1.8 kg (4 lb), and spends its first few months of life in constant physical contact with its mother. It begins to walk at around four or five months, and starts to put plant parts in its mouth between four and six months. At eight months it regularly ingests solid food. Weaning occurs around three years of age, although juveniles may remain with their mothers for years after that.
 
Young male and female gorillas are considered infants from birth until three years of age, juvenile between the ages of about three and six, and sub adult from six to about eight years old. Black backs are sexually immature males from around eight years until they have developed the silver saddle and large canines of maturity. Females begin to ovulate at 7 or 8 years of age, and have their first infant between the ages of 10 and 12. Males generally do not start breeding before the age of 15.
 
The Mountain Gorilla has no mating season and females usually initiate mating behaviour. The length of their menstrual cycle is about 28 days with 1-3 fertile days, and ovulation ceases for 3–5 years after reproducing. The length of gestation is eight and a half months. Females generally rear one infant every 6 to 8 years, and may leave only 2–6 offspring over a 40 year life span. Males that have harems of 3–4 females increase their reproductive output by fathering 10-20 offspring over 50 years.
 
Social structure
The Mountain Gorilla is highly social, and lives in relatively stable, cohesive groups held together by long-term bonds between adult males and females.

Relationships among females are relatively weak. These groups are non-territorial; the silverback generally defends his group rather than his territory. In the Virunga Mountain Gorillas, the average length of tenure for a dominant silverback is 4.7 years.
 
61% of groups are composed of one adult male and a number of females and 36% contain more than one adult male. The remaining gorillas are either lone males or exclusively male groups, usually made up of one mature male and a few younger males. Group sizes vary from five to thirty, with an average of ten individuals. A typical group contains: one silverback, who is the group's undisputed leader; one or two blackbucks, 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.
 
Most males, and about 60% of females, leave their natal group. 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.
 
The dominant silverback generally determines the movements of the group, leading it to appropriate feeding sites throughout the year. He also mediates conflicts within the group and protects it from external threats. Experienced silverbacks are capable of removing poachers' snares from the hands or feet of their group members. He is the centre 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 his abandoned offspring, even allowing them to sleep in his nest.
 
When the dominant silverback dies or is killed by disease, accident, or poachers, the family group may be severely disrupted. Unless he leaves behind a male descendant capable of taking over his position, the group will either split up or be taken over in its entirety by an unrelated male. 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 an effective reproductive
strategy, in that the newly acquired females are then able to conceive the new male's offspring. Infanticide has not been observed in stable groups.
 
Behaviour Aggression
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. For this reason, conflicts are most often resolved by displays and other threat behaviours that are intended to intimidate without becoming physical. The ritualized charge display is unique to gorillas. The entire sequence has nine steps: hooting slow to fast, symbolic feeding, rising bipedally, throwing vegetation, chest-beating with cupped hands, one leg kick, sideways running, two-legged to four-legged, slapping and tearing vegetation, and thumping the ground with palms to end display.
 
Affiliation
The midday rest period is an important time for establishing and reinforcing relationships within the group. Mutual grooming reinforces social bonds, and helps keep hair free from dirt and parasites. It is not as common among gorillas as in other primates, although females groom their offspring regularly. Young gorillas play often and are more arboreal than the large adults. Playing helps them to learn how to communicate and behave within the group. Activities include wrestling, chasing and somersaults. The silverback and his females tolerate and even participate if encouraged.
 
Vocalization
Twenty-five distinct vocalizations are recognized, many of which are used primarily for group communication within dense vegetation. Sounds classified as grunts and barks are heard most frequently while travelling, 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 intergroup communication.