Gorilla Beringei
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The eastern gorilla (''Gorilla beringei'') is a
critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of the
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
''
Gorilla Gorillas are primarily herbivorous, terrestrial great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five su ...
'' and the largest living
primate Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...
. At present, the species is subdivided into two
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
. There are 6,800
eastern lowland gorilla The eastern lowland gorilla (''Gorilla beringei graueri'') or Grauer's gorilla is a Critically Endangered subspecies of eastern gorilla endemic to the mountainous forests of eastern Democratic Republic of the Congo. Important populations of th ...
s or Grauer's gorillas (''G. b. graueri'') and 1,000
mountain gorilla The mountain gorilla (''Gorilla beringei beringei'') is one of the two subspecies of the eastern gorilla. It is listed as endangered by the IUCN . There are two populations: One is found in the Virunga Mountains, Virunga volcanic mountains of C ...
s (''G. b. beringei''). Illegal hunting threatens the species.


Taxonomy and phylogeny

There are two recognised
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
of eastern gorilla: the
mountain gorilla The mountain gorilla (''Gorilla beringei beringei'') is one of the two subspecies of the eastern gorilla. It is listed as endangered by the IUCN . There are two populations: One is found in the Virunga Mountains, Virunga volcanic mountains of C ...
(''Gorilla beringei beringei'') of the
volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...
slopes of Rwanda, Uganda and eastern Democratic Republic of Congo; and the
eastern lowland gorilla The eastern lowland gorilla (''Gorilla beringei graueri'') or Grauer's gorilla is a Critically Endangered subspecies of eastern gorilla endemic to the mountainous forests of eastern Democratic Republic of the Congo. Important populations of th ...
or Grauer's gorilla (''Gorilla beringei graueri'') in eastern Democratic Republic of Congo. The eastern lowland gorillas and mountain gorillas were previously thought to be two of the three subspecies of one single species, the gorilla (''Gorilla gorilla''). However, genetic research has shown that the two eastern subspecies are far more closely related than the western subspecies: the
western lowland gorilla The western lowland gorilla (''Gorilla gorilla gorilla'') is one of two Critically Endangered subspecies of the western gorilla (''Gorilla gorilla'') that lives in Montane ecosystems#Montane forests, montane, Old-growth forest, primary and sec ...
(''G. gorilla gorilla''), which justified the separate classification. The two eastern subspecies are now classified as ''G. beringei''.


Description

The eastern gorilla is a large
hominid The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); '' Gorilla'' (the ...
with a large head, broad chest, and long arms. It has a flat nose with large nostrils. The face, hands, feet and breast are bald. The fur is mainly black, but adult males have a silvery "saddle" on their back. When the gorilla gets older, the hair on the saddle of the back becomes white, much like the gray hair of elderly people. This is why the older males are called ''silverbacks''. Grauer's gorilla has a shorter, thicker, deep black fur, while the mountain gorilla has a more bluish color. The mountain gorilla is slightly smaller and lighter than Grauer's gorilla, but still larger and heavier than the western lowland gorilla and the Cross River gorilla. Males are much larger than females. A full-grown male eastern gorilla typically weighs and stands upright and a female typically weighs and stands tall.Burnie D and Wilson DE (Eds.), ''Animal: The Definitive Visual Guide to the World's Wildlife''. DK Adult (2005), . The tallest silverback recorded was a individual shot in Alimbongo, northern
Kivu Kivu is the name for a large region in the eastern Democratic Republic of the Congo that borders Lake Kivu. It was a ''Région'' (read 'province') of the country under the rule of Mobutu Sese Seko from 1966 to 1988. As an official ''Région'' ...
in May 1938. The heaviest gorilla recorded was a silverback shot in
Ambam Ambam is a town and commune in the Vallée-du-Ntem department, South Province, Cameroon on the border with Equatorial Guinea and Gabon. This frontier town is located approximately 220 km from Yaoundé and as of 2005 had a population of 41 ...
,
Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...
, which weighed ,Wood, Gerald L. (1983) ''The Guinness Book of Animal Facts and Feats''. Sterling Pub Co Inc. although the latter area is within the range of the western gorilla, far outside that of the eastern gorilla.


Distribution and ecology

Mountain gorillas are restricted to the mountain
rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...
and subalpine forest of eastern Democratic Republic of the Congo (DRC), southwestern Uganda and Rwanda. Grauer's gorilla occur across the forests of the
Albertine Rift The Albertine Rift is the western branch of the East African Rift, covering parts of Uganda, the Democratic Republic of the Congo (DRC), Rwanda, Burundi and Tanzania. It extends from the northern end of Lake Albert to the southern end of Lake Tan ...
in eastern DRC. Eastern gorillas are herbivorous, with a heavily foliage based diet, due to lack of available fruit in their habitats. They have smaller home ranges than western gorillas as foliage is more abundant than fruit. They are diurnal but the majority of foraging occurs in the morning and late afternoon. At night, they build nests by folding over vegetation, usually on the ground.


Behavior

Eastern gorillas live in stable, cohesive family groups, led by a dominant silverback male. Eastern gorillas tend to have larger group sizes than their western relatives, numbering up to 35 individuals. There is no distinct breeding season and females give birth only once every 3–4 years due to the long period of parental care and a gestation period of 8.5 months. Newborn gorillas have greyish-pink skin and can crawl after 9 weeks; they are not fully weaned until 3.5 years. Males defend their females and offspring using their large size in intimidating displays involving charging and chest-beating.


Conservation status

The eastern gorilla has become increasingly endangered since the 1990s, and the species was listed as critically endangered in September 2016 as its population continued to decrease. Primary threats to the eastern gorilla include habitat destruction for residential, commercial, and agricultural purposes,
habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...
caused by transportation corridors and resource extraction, as well as disease. Between 1996 and 2016, the eastern gorilla lost more than 70 percent of its population, and by 2016 the total population was estimated to be less than 6,000. An exception to this declining trend is the mountain gorilla. According to the most recent estimates, there are approximately 1,004 mountain gorillas, and their numbers continue to grow. In some
national park A national park is a nature park designated for conservation (ethic), conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land that is protecte ...
s, viewing mountain gorillas is a popular
tourist attraction A tourist attraction is a place of interest that tourists visit, typically for its inherent or exhibited natural or cultural value, historical significance, natural or built beauty, offering leisure and amusement. Types Places of natural beaut ...
. These national parks include
Volcanoes National Park Volcanoes National Park is a national park in northwestern Rwanda. It covers of rainforest and encompasses five of the eight volcanoes in the Virunga Mountains, namely Karisimbi, Bisoke, Muhabura, Gahinga and Sabyinyo. It borders Virunga ...
in Rwanda,
Virunga National Park Virunga National Park is a national park in the Albertine Rift Valley in the eastern part of the Democratic Republic of the Congo. It was created in 1925. In elevation, it ranges from in the Semliki River valley to in the Rwenzori Mountains. ...
in the Democratic Republic of the Congo, and
Mgahinga Gorilla National Park Mgahinga Gorilla National Park is a national park in southwestern Uganda. It was created in 1991 and covers an area of . Geography Mgahinga Gorilla National Park is located in the Virunga Mountains and encompasses three inactive volcanoes, name ...
and Bwindi Impenetrable National Park in Uganda. While ecotourism can benefit gorilla populations by generating revenue for conservation efforts, there is concern that increased exposure to humans will place gorillas at greater risk of contracting zoonotic diseases. Studies have shown that a troop of habituated eastern gorilla, that is, that that leave protected areas to forage in surrounding communities, have higher disease rates than their unhabituated counterparts, with nearby humans and livestock as the likely sources of transmission. Unlike the western gorilla, there are few eastern gorillas in zoos. The
Antwerp Zoo Antwerp Zoo () is a zoo in the centre of Antwerp, Belgium, located next to the Antwerpen-Centraal railway station. It is the oldest animal park in the country, and one of the oldest in the world, established on 21 July 1843. History Since its ...
is the only zoo outside the native range of the species that has eastern gorillas. Outside the native range, the mountain gorilla is not held in captivity at all. Small groups consisting of animals confiscated from poachers are kept in the Democratic Republic of Congo: Grauer's gorillas at the Gorilla Rehabilitation and Conservation Education (GRACE) center in , and mountain gorillas at the Senkwekwe Center in
Virunga National Park Virunga National Park is a national park in the Albertine Rift Valley in the eastern part of the Democratic Republic of the Congo. It was created in 1925. In elevation, it ranges from in the Semliki River valley to in the Rwenzori Mountains. ...
.


References


External links


Animal Diversity Web: ''Gorilla beringei''
{{Authority control
eastern gorilla The eastern gorilla (''Gorilla beringei'') is a critically endangered species of the genus ''Gorilla'' and the largest living primate. At present, the species is subdivided into two subspecies. There are 6,800 eastern lowland gorillas or Grauer ...
Mammals of the Democratic Republic of the Congo Mammals of Rwanda Mammals of Uganda Critically endangered fauna of Africa
eastern gorilla The eastern gorilla (''Gorilla beringei'') is a critically endangered species of the genus ''Gorilla'' and the largest living primate. At present, the species is subdivided into two subspecies. There are 6,800 eastern lowland gorillas or Grauer ...
eastern gorilla The eastern gorilla (''Gorilla beringei'') is a critically endangered species of the genus ''Gorilla'' and the largest living primate. At present, the species is subdivided into two subspecies. There are 6,800 eastern lowland gorillas or Grauer ...