Grauer’s Gorilla

There are two species of gorilla, the eastern gorilla (Gorilla beringei) and western gorilla (Gorilla gorilla). The eastern species consists of two subspecies: Gorilla beringei beringei (mountain gorilla) and Gorilla beringei graueri (Grauer’s gorilla, formerly incorrectly known as the eastern lowland gorilla). Grauer’s gorilla is classified as Critically Endangered on the IUCN Red List of Threatened Species, which means it faces a very high risk of extinction in the wild (Plumptre et al. 2016).

Grauer’s gorilla occurs only in eastern Democratic Republic of the Congo (DRC) and is found in the forests east of the Lualaba River and the Burundi-Rwanda-Uganda border. Grauer’s are thought to inhabit three major regions: the Maiko-Tayna region, encompassing Maiko National Park, Tayna Nature Reserve and the Kisimba-Ikobo Nature Reserve (this area also encompasses the “North Kivu” populations described by Hall et al. 1998a); the Kahuzi-Kasese region (encompassing Kahuzi-Biega National Park and Oku Community Reserve); and the Itombwe Massif. There are four large populations (Itombwe, Kahuzi-Biega, Kasese, Maiko and Tayna) and several small, isolated populations (e.g., Mt. Tshiaberimu and Walikale) (Maldonado et al. 2012).

Surveys in 1994 and 1995 estimated that there were around 16,900 Grauer’s gorillas in eastern DRC (Hall et al. 1998b). But civil war engulfed the region from 1996 to 2003, making much of the range inaccessible. Only recently have surveys been possible and a new population estimation derived, and this showed a drastic reduction to only about 6,800 individuals (Plumptre et al. 2021).

Threats

Grauer’s gorillas have been hunted for their meat for millennia, but today gorillas are poached with automatic weapons that have become widely available. The recent and drastic decline in their numbers is due mainly to intense hunting pressure in the gorillas’ stronghold of Kahuzi-Biega National Park. This was associated with illegal mining and with rebel groups occupying the park. Hunting was commercially driven to feed both mine workers and military personnel (Spira et al. 2019).

Human settlement is accelerated in some areas by mining. High demand for coltan, a highly valued metal used in the manufacture of mobile telephones and computer equipment, and abundant in rivers around Kahuzi-Biega, has lured people into illegal mining camps. Mining for tin (cassiterite) and gold is present throughout Grauer's gorilla range, cassiterite especially in the area between Maiko and Kahuzi-Biega, and diamond mining is common in the north, specifically in Maiko National Park (Plumptre et al. 2016).

Loss and fragmentation of gorilla habitat results from the westerly movement of the growing human population and from agricultural and pastoral expansion. Currently there is no commercial logging in G .b. graueri range, but low-level extractive activities (e.g., charcoal production and wood cutting) are an ongoing threat, even if artisanal in scale. Destruction of high altitude forest threat threatens remnant populations.

Increased exposure of gorillas to humans or their faeces has occurred with people mining or simply taking refuge in the forests. Disease may also be carried by park guards, researchers and tourists. Given the use of tourism as a key strategy in gorilla conservation, strict guidelines have been developed to minimize disease risks (Macfie & Williamson 2010).

Conservation

Much less is known about Grauer’s gorilla in comparison to the mountain gorilla and is largely attributable to warfare throughout its range. Most subpopulations are found in protected areas, where international NGOs are working with government authorities to support rehabilitation and conservation programmes, e.g., in Kahuzi-Biega NP, Maiko NP, Tayna Nature Reserve and Kisimba-Ikobo Nature Reserve (Robbins et al. 2008). The military and political situation however remains highly unstable, and it is very difficult for conservationists to undertake fieldwork and to fully engage with local communities (Ferris et al. 2005).

In 2012, a consortium of NGOs working developed conservation strategies and priorities to safeguard the great ape populations in in eastern DRC (Maldonado et al. 2012). The Itombwe forest has been highlighted as an important area of conservation focus (Hall et al. 1998a). Government authorities (ICCN) created the Itombwe Nature Reserve to help protect the remaining yet highly endangered and fragmented Itombwe populations. The Maiko Tayna region has been previously overlooked yet it could support the most significant populations outside of the Kahuzi-Biega NP. Efforts have focused on developing community based reserves in the Tayna and Kisimba Ikoba regions and providing support for conservation activities in Maiko NP. Up-to-date information on the distribution and abundance of G. b. graueri across the range is urgently needed to establish new baselines for monitoring, identify key populations and to direct and prioritize conservation actions (Williamson & Butynski 2013; Robbins et al. 2008).

Support is needed in areas where protection is already established, but at the same time conservation activities need to be initiated in the more remote and inaccessible sectors of Grauer’s gorilla range (Plumptre et al. 2016; Williamson & Butynski 2013).

References

Hall, J.S., Saltonstall, K., Inogwabini, B.I. & Omari, I. (1998a) Distribution, abundance and conservation status of Grauer’s gorilla. Oryx 32: 122–130.

Hall, J.S., White, L.J.T., Inogwabini, B.I., Omari, I., Morland, H.S., Williamson, E.A., Saltonstall, K., Walsh, P., Sikubwabo, C., Bonny, D., Kiswele, K.P., Vedder A., Freeman, K. (1998b). Survey of Grauer’s gorillas (Gorilla gorilla graueri) and eastern chimpanzees (Pan troglodytes schweinfurthii) in the Kahuzi-Biega National Park lowland sector and adjacent forest in eastern Democratic Republic of Congo. International Journal of Primatology 19: 207–235.

Macfie, E.J. & Williamson, E.A. (2010). Best practice guidelines for great ape tourism. IUCN SSC Primate Specialist Group, Gland, Switzerland.

Maldonado, O., Aveling, C., Cox, D., Nixon, S., Nishuli, R., Merlo, D., Pintea, L. & Williamson, E.A. (2012). Grauer’s Gorillas and Chimpanzees in Eastern Democratic Republic of Congo (Kahuzi-Biega, Maiko, Tayna and Itombwe Landscape): Conservation Action Plan 2012–2022. IUCN SSC Primate Specialist Group, Ministry of Environment, Nature Conservation & Tourism, Institut Congolais pour la Conservation de la Nature & Jane Goodall Institute, Gland, Switzerland.

Plumptre, A., Nixon, S., Caillaud, D., Hall, J.S., Hart, J.A., Nishuli, R. & Williamson, E.A. (2016). Gorilla beringei ssp. graueri. The IUCN Red List of Threatened Species 2016: e.T39995A17989838.

Plumptre, A.J., Kirkby, A., Spira, C., Kivono, J., Mitamba, G., Ngoy, E., Nishuli, R., Strindberg, S., Maisels, F., Buckland, S., Ormsby, L. & Kujirakwinja, D. (2021). Changes in Grauer's gorilla (Gorilla beringei graueri) and other primate populations in the Kahuzi-Biega National Park and Oku Community Reserve, the heart of Grauer's gorilla global range. American Journal of Primatology 83: e23288.

Spira, C., Kirkby, A., Kujirakwinja, D. & Plumptre, A.J. (2019). The socio-economics of artisanal mining and bushmeat hunting around protected areas: Kahuzi–Biega National Park and Itombwe Nature Reserve, eastern Democratic Republic of Congo. Oryx 53: 136–144

Williamson, E.A. & Butynski, T.M. (2013). Gorilla beringei eastern gorilla. In: Mammals of Africa. Volume II: Primates. T.M. Butynski, J. Kingdon & J. Kalina (eds.). Bloomsbury Publishing, London, UK, pp. 45–53.