Actual and potential threat
The major threats affecting or having affected Mountain Gorilla populations are (1) habitat loss or modification and forest encroachment (Muruthi et al., 2000), (2) disease and disease transmission from humans and (3) war or political unrest (Plumptre et al., 2003; Muruthi et al., 2000; IUCN, 2002).
Degradation and decline of habitats
The Mountain Gorilla lives in a region where there is a very high human population. In eastern DRC, Rwanda and Uganda fragments of forest form part of a landscape that supports one of the highest densities of rural human populations in Africa (Taylor et al., 1999). The main threat to gorillas in DRC is forest clearance by refugees and, although no land has been appropriated from the habitat of the Virunga gorillas, declines may be due to the presence of livestock in the Virungas (IUCN, 1982). Deforestation to supply refugees’ demand for fuelwood affected 105 km² of the park in 2003, of which 35 km² has been completely stripped, though not in the Mikeno sector, where the gorillas are found (UNEP -WCMC, 2003b).
,Relatively intensive illegal woodcutting and the extraction of gold and production of charcoal do occur in certain areas. In the long or medium term, agricultural encroachment is the major threat to forest integrity (UNEP-WCMC, 2003a). The Bwindi-Impenetrable National Park population is relatively well protected. Historically, only about 10% of BINP remained free from human disturbance (UNEP-WCMC, 2003a).
Direct exploitation – The bushmeat trade
Mountain Gorillas are not usually hunted for bushmeat, but they are frequently maimed or killed by traps and snares intended for other animals (Plumptre & Williamson, 2001). Very recent information suggests that a few mountain gorillas have been killed for their meat (Wildlife Direct, 2007).
Other forms of direct exploitation
In the past Mountain Gorillas were killed for their heads, hands, and feet, which were sold to collectors, and a few infants have been captured for potential illegal sale to zoos. Binyeri et al. (2002) reported a number of incidents in the Virunga National Park of DRC in which infant gorillas were abducted for sale, and several adults killed to gain access to the infants, Williamson and Fawcett (2008) reported similar incidents in Rwanda.
Diseases
Another potential threat to gorillas is exposure to human dis eases (e.g Graczyk et al., 2001; Graczyk et al., 2003) particularly for habituated gorillas that come into contact with humans, in areas of gorilla tourism (Homsy 1999). Gorilla tourism exposes gorillas to humans and hence to any diseases that humans may be carrying, some of which the gorillas may never have been exposed to before. An outbreak of a respiratory disease, with the possibility of measles as the primary infection, in the Volcanoes NP in Rwanda claimed six gorilla lives, and 27 other gorillas were successfully treated (Wallis & Lee, 1999). Strict rules are in place to regulate tourist visits (Homsy 1999).
Beside severe impacts on human populations, several outbreaks of the Ebola virus since 2000 might have claimed thousands of great apes in Africa. Ebola hemorrhagic fever is a severe, often fatal disease that affects humans, gorillas and chimpanzees. Many scientists believe the disease is spread through the butchering and handling of primate bushmeat. Mountain Gorillas have not yet been affected.
Impact of Conflicts
The impact of wars and political conflicts is particularly well documented for the Mountain Gorilla. The early 1990s saw the
outbreak of fighting in Rwanda, which by April 1994 resulted in a stream of refugees pouring into gorilla habitat in DRC. Shortly afterwards came the 1996 war between the armed forces of DRC and a rebel movement. Subsequently fighting again broke out in 1998 between Rwandan and Ugandan troops on the one side and the DRC army on the other.
The displacement of refugees during these conflicts led to uncontrolled firewood harvesting, increased poaching in the Virunga National Park and disruption of natural animal migration patterns (UNEP-WCMC, 2003b). Three of the four refugee camps in North Kivu were located in or near to the park, and it is estimated that at least 500,000 ha of the park were affected by wood harvesting or poaching (UNEP-WCMC, 2003b). Kalpers et al. (2003) report that between 12 and 17 gorillas are known to have died between 1992 and 2000 in the Virungas Volcanoes Region as a direct result of military activity. Concern for the protection and management of the site, especially with regards to recurring encroachments, deforestation, poaching, population growth, and the refugee-related problems that have arisen due to civil unrest in Rwanda, led to Virunga National Park being placed on the World Heritage in Danger List in 1994 (UNESCO, 1994).
The situation around the Virungas remains unstable and militia groups are still active in the region. Much of the Virungas has been severely affected by this civil war, the continuous political unrest and economic instability. The ongoing conflict has caused the death of several guards in the last two years and has made wardening of the area extremely difficult and dangerous. The conflict remains a threat to the Virungas gorillas and to the protected areas.
Other threats
Accidental entrapment in wire snares used to trap other wild animals is also a threat to the mountains gorillas. Plumptre et al. (1997) stated that the setting of snares for ungulates in the Volcanoes National Park, Rwanda is one of the greatest threats to Gorilla beringei beringei. The isolation and low numbers of Mountain Gorillas have given rise to concerns about inbreeding (Garner & Ryder, 1996). The two populations of Mountain Gorilla are too small to meet theoretical survival criteria, and are vulnerable to catastrophic events such as outbreaks of disease, sudden wide loss of habitats, and would quickly be decimated by poaching if the vigilance of conservationists were to be relaxed. International trade in live gorillas and gorilla parts, which used to be a threat, has declined since the gorilla was listed in Appendix I of CITES.