Mountain Gorillas so rare, why?
There are so few mountain gorillas remaining for several reasons. First the size of their habitat is rather small. Bwindi forest is only 33 km sq and the Virunga volcanoes 450 km sq. These two forests are surrounded by highly populated rural areas (200-400 people per sq km). Here, people make their living through subsistence farming.
The gorillas are threatened by mostly habitat destruction, poaching and disease. The forests can be slowly degraded by people illegally harvesting trees or other forest products. This reduces its suitability for the gorillas.
People living around Bwindi and the Virungas do not eat primates as bush-meat. However poachers do set snares to capture forest antelopes. The gorillas may get caught instead. In recent years, poaching for the pet trade has been on the increase.
The gorillas get diseases, either respiratory or parasitic that may be transmitted from people. Being in close contact with the gorillas increases the risk of disease transmission. The guidelines for tourists are designed to protect both the gorillas and you from getting sick- so please follow them.
How many mountain gorillas are there?
There are only about 700 Mountain gorillas. They are critically endangered. Mountain gorillas are found in only 2 small populations- in the Virunga volcanoes of Uganda, Rwanda and democratic Republic of Congo and in Bwindi impenetrable national park.
Bwindi has approximately 300 gorillas and the rest are found in the Virunga Volcanoes.
Gorillas and their changes in the population size, are monitored by conducting censuses of the whole park every after about 5 years. To do this, the entire parks are intensively search for signs of the gorillas. Then group sizes and composition are estimated based on the number of nest per group. In 2006, genetic analysis of the gorilla feces were used to confirm the identity of groups and individuals.
Social interactions of Mountain Gorillas
Gorillas are very social, with all group members coordinating their daily activities. A typical day consists of several hours feeding and moving through the forest. They rest for a few hours. Usually interactions among individuals are peaceful. Occasionally conflicts arise over feeding spots, with individuals giving aggressive ‘cough grant’ vocalizations, screaming and even fighting.
Silverbacks are dominant over all other group members. Dominance exist among adult female members and among silverbacks in multi-male groups. Males may compete for access to females both within multi male groups as well as between groups.
Inter-group encounters occur about once a month; this is the only opportunity for females to transfer between social units. It is the time for males to out-compete their opponents and appear more impressive to attract females.
Friendly interactions among gorillas consist of resting together and grooming infants. Juveniles have endless energy for playing.
A typical group of gorillas consists of about 10 members: the dominant silverback, several adult females and the immature offspring of various ages. However, there can be a lot of variation. Group size may range from 2 to 30 or more individuals. Groups may contain more than 2 silverbacks; in multi male groups, the silverbacks are usually related as brothers, half brothers or father and son.
When gorillas reach maturity, they typically but not always, leave the group in which they were born. Females will transfer directly to another group when they are 6-10 years. Males follow one of two strategies to become the leader of a group: either remain in the group and try to take over, or emigrate to become a solitary male and eventually form a new group. All male gorillas become silverbacks at the age of 14 years but not all males become group leaders.
Reproduction of Mountain Gorillas
Females have their first offspring at about age 10. Gestation is 8.5 months. About 1 in 3 babies born do not survive beyond age three. Gorillas may live into their early 40s. Because females have babies every 4-5 years, each female may have only 4 offspring that survive to adulthood. Silverbacks may be dominant for 10 or more years and sire 5, 10 or more offspring. Through genetic analysis, we know that subordinate silverbacks in multi male groups do sometimes sire offspring.
Diet and Ranging
Gorillas are vegetarians. Their diet consists of leaves, stems and fruit from the wide variety of vegetation found in the forest. Most people are surprised that gorillas do not eat any meat with the exception of the occasional ant or termite.
Why are gorillas so big and strong, yet do not eat meat? Imagine spending 5-6 hours a day eating only salad or vegetables- that is how they get enough to eat. Gorillas’ stomachs are so big not because they are fat but because they digest all that vegetation.
The diet of mountain gorillas varies quite a lot, depending on what is available. For example, some plants that are quite common in the low altitude area of Buhoma are rare or absent from the higher altitude areas of the park such as Ruhija. The gorillas also select foods that are high in proteins and carbohydrates but relatively low in fiber.
Bwindi gorillas enjoy fruit and they will not hesitate to climb 20 meters or more to eat it. However, it is available at only certain times of the year. Also as altitude increases, fruit availability declines. So the gorillas in Buhoma have more fruit than those in Ruhija and the mountain gorillas in Virunga Vocanoes consume almost no fruit at all.
In Bwindi, gorillas travel about 1 km a day. How far they move depends on the amount of available food. They travel further when they are searching for fruit than when they are eating only vegetation. They may also travel a lot if they have had an encounter with another group- one Silverback may be trying to move his group away from the other one.
Each group occupies a home range of about 10-30 square km. The home range of neighboring groups, typically overlap with one another.
Gorillas are naturally afraid of humans. They typically will flee or aggressively charge if people get too close to them. Gorillas that are visited by people have undergone ‘habituation’. This is the process, where gorillas go through daily contact with humans. Gorillas have slowly lost their fear of humans and have learnt to view them as neutral beings in their environment.
Habituating a group of gorillas usually takes about 2 years. The guidelines established for tourist visits have been developed to respect the special relationship that exists through habituation: the gorillas briefly letting us into their world.
The Uganda Wildlife Authority and several conservation organizations work intensely to protect the gorillas through a multi-prolonged approach.
Park rangers routinely patrol the park to reduce illegal activities, cut snares and catch poachers.
The permit fees generate revenue to protect Bwindi. Additional employment is created for the local people working as porters, artisans, restaurant workers and others in the tourism industry.
Several projects aim to improve the livelihood of local people through improving agricultural practices and development of small business practices. Assistance is also given through the construction of schools, roads and health clinics.
Research and monitoring
To conserve the gorillas, we must understand their ecological and behavioral patterns. We must also have information to know how the gorilla population and their habitat are changing over time.
Veterinary medicine and Public health
Veterinarians are always on standby to remove snares or treat the gorillas for respiratory illnesses. They also monitor gorilla health. Improving public health practices benefits both the communities and the mountain gorillas.
Information source: Uganda Wildlife Authority