Gorilla: Conservation Status
Habitat
The Gorilla is a forest species. They inhabit tropical rain forests, forest edges and clearings, riverine forests, swamps, and abandoned, cultivated fields.
Western gorillas and Eastern Lowland Gorillas live in tropical forests (Congolian Coastal Forests and Guinean Moist Forests) where herb densities are lower and fruit is more abundant compared to the high-altitude montane forests which is the characteristic habitat of the mountain gorillas (reviewed in Doran & McNeilage, 1998, 2001). Many, but not all, western gorilla habitats include localised, open clearings covered with year-round herbaceous vegetation (Magliocca et al., 1999; Parnell, 2002), or large swamps bordering rivers (Blake et al., 1995; Fay et al., 1989; Nishihara, 1995).
Distribution (current and historical)
Gorillas are found in two widely separated areas of Africa. The western and eastern populations were probably separated first by the massive inland Congo basin lake of the Miocene, and then, from about 5 millions years ago, by the gradual drying of the region and the retreat of forest to higher areas. Subsequently, gorillas have not spread back into the central Congo basin, either because they have not had time, or because the heavily shaded primary forest there does not allow the growth of sufficient ground vegetation to support such a large, predominantly terrestrial animal (MacDonald ed., 2001).
Although they are found over only a small area of Africa, gorilla habitat include a wide range of altitudes from sea level in west Africa to 3790m in the east. Oddly enough, it is the Mountain Gorilla (G.g.beringei) found in the extreme east and at the highest altitude that is the best known form; the behaviour of western gorillas is relatively little known.
Population estimates and trends
The gorilla is a forest dwelling species, most of whose numbers live outside protected areas. A usable index of potential decline in gorilla habitat can be the national rates of disappearance of "moist forest" (Harcourt, 1996). The rate of forest destruction in Africa correlates strongly with human density and the countries economies, and will presumably continue to increase in all African countries (Barnes, 1990). The best available estimates indicate that the world gorilla population is above 100.000 individuals (112.000, Butynski, 2001; 125.000, MacDonald, 2001). According to the IUCN Red List (2002), all taxons are considered "endangered" (EN A2cd).
With the exception of the Mountain Gorilla however, accurate population estimates for gorillas are difficult to establish, because their hugely vast range has not yet been thoroughly surveyed. Population counts and estimates of gorillas are commonly carried out on the basis of nest or sleeping site counts (e.g. Inogwabini et al., 2000). Adults and immature weaned animals build new nests to sleep in each night. The nests are counted and any dung adjacent to each nest examined gives a reliable indication of group size as well as age of animal, particularly when the counts are repeated over several nights.
Threat data
The major threats to gorilla populations are habitat loss or modification (e.g. through deforestation, wood extraction, infrastructure development, human settlement and agricultural crops (IUCN, 2002) and forest encroachment (Muruthi et al., 2000), direct killing (for the bushmeat trade mostly) or hunting (for live animals trade), disease and disease transmission from humans and war or political unrest (Plumptre et al., 2003; Muruthi et al., 2000; IUCN, 2002).
Preservation’s projects
There are many preservation’s projects existing for gorillas. The majority of which concerns the Mountain’s Gorilla ; the other sub-species haven’t been followed or have been considered as in a more favourable conservation status.
In Rwanda, three schemes have been specifically put in place for the protection of the Volcanoes National Park’s Mountains Gorillas. These initiatives include the research center of Karisoke, established in 1967, the Mountains Gorilla’s project, started in 1978 and the veterinary center of Virunga established in 1987 (Anon, 1989)
The nature-based tourism contributes for a significant unit of the Rwanda’s economy, creating incomes in plenty to bear the park’s functioning.
A follow-up of the ground carried out in 1987 by the Nigerian Conservation Foundation, supported by the British Council, made it possible to evaluate the Gorilla’s population living in the state of the Cross-River ; in the south-east of Nigeria, to 300 (Harcourt et al., 1988). Since then, a scheme aiming at favouring the Gorilla’s preservation’s status and habitat have been put in place. The campaing to raise local residents awareness insists on the (lasting) contribution that the wild fauna’s preservation, rather than its hunting to extinction, permit.
From February 1990, Fauna Flora International, in partnership with African Wildlife Foundation and the WWF developped the Mountain’s Gorilla project and created the International Gorilla Conservation Programme (IGCP). The IGCP objectives are to support the preservation efforts all across the Eastern Gorillas (Gorilla beringei beringei & G.b.graueri) distribution area. The lowlands ones as well as those of mountains in RDC, Ouganda and Rwanda. And that by promoting the cooperation between these three states via a financial and technical help (Anon, 1994 ; Kalpers, 1993)
