Eastern lowland gorilla

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Eastern lowland gorilla
Flachlandgorilla.jpg
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Family: Hominidae
Genus: Gorilla
Species: G. beringei
Subspecies: G. b. graueri
(Matschie, 1914)
Trinomial name
Gorilla beringei graueri
(Matschie, 1914)
Gorilla beringei graueri distribution.svg
Geographic range in Africa

Grauer's gorilla, formerly known as the eastern lowland gorilla (Gorilla beringei graueri) is a subspecies of eastern gorilla endemic to the mountainous forests of eastern Democratic Republic of the Congo. Important populations of this gorilla live in the Kahuzi-Biega and Maiko National Parks and their adjacent forests, the Tayna Gorilla Reserve, the Usala forest and on the Itombwe Massif.

It is the largest of the four gorilla subspecies. It has jet black coats like the mountain gorilla (Gorilla beringei beringei), although the hair is shorter on the head and body. The male's coat, like that of other gorillas, turns silver at the back as the animal matures. There are many more western lowland gorillas than the eastern variety; compared to over 100,000 western lowland gorillas, there were only about 5,000 eastern lowland gorillas in the wild in a 2004 report[2] and fewer than 3,800 in a 2016 one.[3] Outside the native range, only two females were in captivity at the Antwerp Zoo in Belgium, per a 1987 book.[4][5]

Physical description[edit]

Grauer's gorillas are the largest subspecies of gorilla and the largest living primates.[6] Males weigh 163 kg (359 lb) on average while females usually weigh half as much.[7] Males have a standing height of 1.69 metres (5 ft 7 in) on average and females stand at 1.60 metres (5 ft 3 in) or less.

Gorillas living in zoos are usually heavier than those in the wild, since they get less exercise and can weigh as much as 270 kilograms (600 lb).[8] One of the largest captive gorillas was a male named Phil that lived between 1941 and 1958 at the St. Louis Zoo, estimated to weigh 250 kilograms (550 lb).[9] Phil's recorded measurements were: height 1.7 m (5.6 ft), bust 182 cm (72 in), neck 91.5 cm (36.0 in), and wrist 25.4 cm (10.0 in).[10]

Habitat and ecology[edit]

Gorillas spend long hours feeding on plant matter every day. Groups are stable apes as they stay together for months and years at a time, much like the structure of a family.[11] In comparison to the Western Gorillas, groups of Grauer's gorillas are usually larger.[11]

Grauer's gorilla has the widest altitudinal range of any of the gorilla subspecies as they can be found in mountainous, transitional and lowland tropical forests. One of the most studied Grauer's gorilla population lives in the highlands of Kahuzi-Biega where habitats vary between dense primary forests to moderately moist woodland, to Cyperus swamp and peat bog.[11]

Gorillas do not eat banana fruits, but they may destroy banana trees to eat the nutritious pith. Farmers who have come in contact with gorillas in their plantations have killed the gorilla and obtained a double benefit, protecting their crop and using the meat of the gorilla to sell at the market.[12]

Grauer's gorilla has a varied plants diet including fruits, leaves, stems and bark as well as small insects such as ants and termites.[11] Although they occasionally eat ants, insects form only a minor part of their diet. In comparison to western lowland gorillas, found in low altitude tropical forests.

Behaviour[edit]

Grauer's gorillas are highly sociable and very peaceful, living in groups of two to over 30. A group usually consists of one silverback, several females and their offspring. Silverbacks are the strong, and each group has one dominant leader (see alpha male). These males protect their group from danger. Young silverback males will slowly begin to leave their natal group when they reach maturity, and will then attempt to attract females to form their own group.

Relatively little is known about the social behaviour, history and ecology of Grauer's gorillas, partly because civil war in the Democratic Republic of the Congo. However, some aspects of social behaviour have been studied. For example, gorillas form harems with may include two full-grown males.[11] One third of gorilla groups in East Africa have two grown males in their group.[11]

Most primates are bonded together by the relationship between females, a pattern also seen in many human families. Once they reach maturity, both females and males usually leave the group.[11] Females usually join another group or a lone silverback adult male, whereas males may stay together temporarily, until they attract females and establish their own groups.[13] It is commonly believed that the structure of the gorilla group is to prevent predation.[14]

Reproduction[edit]

A female will give birth a single infant after a gestation period of about 8½ months. They breastfeed for about three years. The baby can crawl at around nine weeks old and can walk at about 35 weeks old. Infant gorillas normally stay with their mother for three to four years and mature at around 8 years old (females) and 12 years old (males).

Conservation and threats[edit]

Male Grauer's gorilla

The primary cause of the decline in Grauer's gorilla populations is poaching for meat.[citation needed] Other reasons for killing gorillas are: instances of killing gorillas as revenge for confiscation of illegal charcoal or other law enforcement, or the destruction of gorilla habitat as a result of logging, charcoal, agricultural expansion or mining.[12] Widespread artisanal mining activities (often controlled by rebel militias) are the major source of hunting pressure for gorillas and other wildlife. Grauer's gorilla is also experiencing a range reduction due to an expanding human population.

Threats to the Grauer's gorilla's survival include: poaching, mining, civil unrest and agriculture.[6]

Civil unrest in the Democratic Republic of Congo has resulted in a decline in Grauer's gorillas. The region inhabited by eastern gorillas has decreased from 8,100 square miles to 4,600 square miles in the past 50 years.[6] This primate species now occupies only 13% of its historical area. Violence in the region has made research difficult, however, scientists have estimated that the population has decreased by more than 50% since the mid-1990s.[6] In the mid-1990s, the population was recorded to nearly 17,000 gorillas.

Civil war[edit]

The civil war in the Democratic Republic of the Congo means military groups remain in the forest for long periods of time. Thus, poaching has increased as militia and refugees become hungry. Military leaders have also disarmed the park security guards in national parks meaning they have virtually no control over the activities that occur within the park, and those that enter it, when faced with armed soldiers. The militia groups present in the region restrict protection of the eastern lowland gorilla. It has been estimated that more than half of the 240 gorillas known in one study have been killed as a result of poaching.[15] Researchers have also stated that it is more difficult to patrol areas outside of the park and expect to find even higher levels of poaching.[15]

Conservation groups negotiated with rebels who control the eastern Democratic Republic of the Congo to re-arm the park guards [15] After the war began, government funding of the park was stopped. Conservation groups,[16] International Gorilla Conservation Program and Deutsche Gesellschaft für Technische Zusammenarbeit (German development agency) have funded the guards for the past several years [15]

Many multinational corporations are indirectly, and some directly, funding the civil war in the Democratic Republic of the Congo by buying illegal resources from the area or by trading resources for military weaponry.[12] Reports from 2007 state that 14,694 tons of cassiterite ($45 million USD), 1,193 tons of wolframite (worth $4.27 million USD) and 393 tons of coltan ($5.42 million USD) were exported in 2007.[12] Coltan in particular is one of the main export resources bought by multinational corporations illegally and is growing in demand due to its use for cellphones. Traxy’s alone bought $226 tonnes of coltan in 2007 which is 57% of the Democratic Republic of the Congo’s entire coltan. The United Nations Environmental Programme reported that resources from multinational corporations and pension funds in industrialized countries are "directed through subsidiary companies to help finance corruption and arms sales, processes that may involve 'conflict' natural resources"[12] Private companies have been found to trade weapons for resources or provide access to weapons through subsidiary companies.[12]

Approximately two million people, directly and indirectly related to the Rwandan genocide in 1994, fled to Tanzania and the Democratic Republic of the Congo, mainly in Virunga National Park.[12] It has been estimated that there were 720,000 refugees living in five camps in the DRC bordering the park (Katale, Kahindo, Kibumba, Mugunga and Lac Vert), 24. Deforestation occurred as 80,000 refugees travelled into the park daily to find wood. Deforestation occurred at a rate of 0.1 km2 per day.[12] Once the Congo war began in 1996, 500,000 refugees remained, putting pressure on the natural resources, including the eastern lowland gorilla.

Bushmeat[edit]

Bushmeat is eaten by displaced peoples residing in the region affected by the civil war, militias groups and loggers and miners.[17] Surveys have shown that great apes, chimpanzees and bonobos comprise 0.5-2% of the meat found in bushmeats markets.[12] Some researchers have found that up to 5 million metric tons of bushmeat are traded annually.[12] This has a detrimental affect on the eastern lowland gorilla populations because of their slow rate of reproduction and their already struggling population.[12] Although gorilla bushmeat only constitutes a small proportion of the bushmeat sold, it continues to encourage a decline in the gorilla populations being subjected to hunting. Endangered Species International stated that 300 gorillas are killed each year to supply the bushmeat markets in the Congo.[12]

Park conservation[edit]

Most parks in the Democratic Republic of the Congo are insecure areas restricting the access of park rangers. Although park rangers are trained to stop illegal hunting, the small number of park rangers do not have access to further training or equipment to handle the militia groups.[12] In the Virunga National Park, for example, 190 park rangers have been killed in just the past 15 years from civil war. Laws in place enforce trans-boundary collaboration and have been proven successful in reducing the decline of the eastern lowland gorilla [12] Illegal extraction of resources from the Virunga National Park has been reduced by policing transportation across borders.[12] This has reduced the financial input available to the militias in the region.[12] Although park rangers have been successful in restricting the amount of illegal resources being transported out of the region, militias groups have retaliated by purposely killing a group of gorillas to threaten the park rangers.[12] On July 22, 2007, 10 gorillas were killed in retaliation for the park rangers' interference with the exportation of illegal resources such as wood.[12]

The militia have remained in control in the region as a result of the neighbouring countries. These militia groups trade minerals and timber illegally in exchange for arms from neighbouring countries, corrupt officials and subsidiaries of many multinational companies.[12] Gorillas are also threatened directly by militia groups because of the prevalence of booby traps placed randomly throughout the forest.[12] Although the eastern lowland gorilla population is directly affected by the violence of militia groups, their population is mainly endangered by habitat disruption from the extraction of natural resources.

Conservation groups negotiated with rebels who control the eastern Democratic Republic of the Congo to re-arm the park guards.[15] After the war began, government funding of the park was stopped. Conservation groups WWF, International Gorilla Conservation Program and Deutsche Gesellschaft für Technische Zusammenarbeit (German development agency) have funded the guards for the past several years.[15]

Logging[edit]

Illegal logging may occur from companies with no rights to the land or by legal landholders. Over-harvesting is an illegal practice often conducted by legal concession holder and encourages deforestation and illegal resources exportation. The areas logged are prime gorilla habitat and is considered an international concern. Companies involved in illegal exploitation therefore encourage environmental destruction in the area and fuel the illegal export industry controlled by militia groups.

Genetic studies[edit]

There was already evidence of inbreeding depression in some gorilla populations, evident through birth defects like syndactyly.[18] A recent genome studies which included all four subspecies gorilla, aimed to identifying the levels of diversity and divergence among the remaining populations of gorilla. Results showed that this the eastern lowland gorilla subspecies was in fact two distinct subgroups.[18] This division could have been due to the small number of individuals sampled, or due to the social structures within the subspecies. Results suggest that within the eastern lowland gorilla subspecies there is an extreme lack of variation, which could reduce the potential of the subspecies to undergo natural selection and adapt to their environment. This lack of diversity is thought to be due to limited number of founders and low levels of migration, which has resulted in a high level of inbreeding in these small population. Conservation interventions for the eastern lowland gorilla have suggested implementing captive breeding programs or translocations between the eastern lowland subgroups.[18]

References[edit]

  1. ^ Robbins, M., Hart, J., Maisels, F., Mehlman, P., Nixon, S. & Williamson, L. (2008). Gorilla beringei ssp. graueri. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 4 January 2009.
  2. ^ Pickrell, J. (2004-03-21). "Eastern lowland gorilla numbers plunge to 5,000, study says". National Geographic News. 
  3. ^ Nuwer, Rachel, "Grauer’s Gorillas May Soon Be Extinct, Conservationists Say", New York Times, April 24, 2016. Retrieved 2016-04-25.
  4. ^ Prince-Hughes, Dawn (1987). Songs of the Gorilla Nation. Harmony. p. 66. ISBN 1-4000-5058-8. 
  5. ^ "Zootierliste". 
  6. ^ a b c d "Eastern lowland gorilla". World Wildlife Fund. Retrieved 23 October 2012. 
  7. ^ Tuttle, Russell H. (1986). Apes of the World: Their Social Behavior, Communication, Mentality and Ecology. William Andrew. ISBN 0815511043. 
  8. ^ Miller, Patricia (1997). Gorillas. p. 64. ISBN 0919879896. 
  9. ^ Leonard, Mary D. (2009). Animals Always: 100 years at the Saint Louis Zoo. p. 208. 
  10. ^ Dobroruka. L. J.: Poloopice an opice (Prosimians and Apes), 2nd ed., Prague, 1983, pp.175-6
  11. ^ a b c d e f g "Eastern lowland gorilla". Year of the Gorilla: 2009. Retrieved 2 November 2012. 
  12. ^ a b c d e f g h i j k l m n o p q r s t Nellemann, Christian; Redmond, Ian; Refisch, Johannes; United Nations Environment Programme (2010). The Last Stand of the Gorilla: Environmental Crime and Conflict in the Congo Basin (PDF). UNEP/Earthprint. p. 86. ISBN 9788277010762. 
  13. ^ Yamagiwa, J (2003). "Bushmeat poaching and the conservation crisis in Kahuzi-Biega National Park, Democratic Republic of the Congo". Journal of Sustainable Forestry 16: 115–135. doi:10.1300/j091v16n03_06. 
  14. ^ Yamagiwa, J.; N. Mwanza; A. Spangenberg; T. Maruhashi; T. Yumoto; A. Fischer; B. Steinhauer. "A census of the eastern lowland gorillas in Kahuzi-Biega National Park with reference to the Mountain Gorillas G. g. beringei in the Virunga region, Zaire". Biologial Conservation 64: 83–89. doi:10.1016/0006-3207(93)90386-f. 
  15. ^ a b c d e f Vogel, Gretchen (Mar 31, 2000). "Conflict in Congo Threatens Bonobos and Rare Gorillas". Science 287 (5462): 2386–2387. doi:10.1126/science.287.5462.2386. Retrieved 2012-09-26. 
  16. ^ WWF
  17. ^ Wilkie and Carpenter, 1999; Fa et al., 2000; Brashares et al., 2004; Ryan and Bell, 2005; Poulsen et al., 2009)
  18. ^ a b c Xue, Yali; Prado-Martinez, Javier; Sudmant, Peter H.; Narasimhan, Vagheesh; Ayub, Qasim; Szpak, Michal; Frandsen, Peter; Chen, Yuan; Yngvadottir, Bryndis (2015-04-10). "Mountain gorilla genomes reveal the impact of long-term population decline and inbreeding". Science 348 (6231): 242–245. doi:10.1126/science.aaa3952. ISSN 0036-8075. PMC 4668944. PMID 25859046. 

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