G. b. beringei
G. b. graueri
Eastern gorilla range
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. Grauer's
gorilla, formerly known as the eastern lowland gorilla (G. b. graueri)
is more populous, at about 3,800 individuals. The mountain gorilla
(G. b. beringei) has only about 880 individuals. The International
Union for the Conservation of Nature mentioned illegal hunting in its
assessment of threats to the species.
1 Taxonomy and phylogeny
2 Physical description
3 Distribution and ecology
5 Conservation status
7 External links
Taxonomy and phylogeny
Mountain gorilla and eastern lowland gorilla
There are two recognised subspecies of eastern gorilla: the mountain
Gorilla beringei beringei) of the volcanic slopes of Rwanda,
Uganda and eastern Democratic Republic of Congo; and Grauer's gorilla
or eastern lowland gorilla (
Gorilla beringei graueri) in eastern
Democratic Republic of Congo.
Grauer's 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 (G. gorilla gorilla), which
justified the separate classification. The two eastern subspecies
are now classified as G. beringei.
The eastern gorilla is a large hominid 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 adult male
Eastern gorilla typically weighs
140–205.5 kg (309–453 lb) and stands 1.7 m
(5.6 ft) upright and a female typically weighs 90–100 kg
(200–220 lb) and stands 1.5 m (4.9 ft) tall.
Wild male eastern gorilla average weight is 163kg  The tallest
silverback recorded was a 1.94-metre (6.4 ft) individual shot in
Kivu in May 1938. The heaviest gorilla recorded
was a 1.83-metre (6.0 ft) silverback shot in Ambam, Cameroon,
which weighed 266 kilograms (586 lb), 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 rainforests and
subalpine forests of eastern Democratic Republic of the Congo,
Uganda and Rwanda. Grauer's gorilla occur across the
forests of the Albertine Rift 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.
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.
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. Illegal
hunting for bushmeat and destruction of their habitat as a result of
intensifying forestry and the development of agriculture form the most
important threats for the species. 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.
The only exception is the mountain gorilla subspecies, which is also
critically endangered but saw its population increase to about 880
individuals in 2016. In some national parks, viewing mountain gorillas
is a popular tourist attraction. These national parks include
Volcanoes National Park
Volcanoes National Park in Rwanda,
Virunga National Park
Virunga National Park in the
Democratic Republic of the Congo, and Mgahinga
Gorilla National Park
Bwindi Impenetrable National Park
Bwindi Impenetrable National Park in Uganda. This has both
advantages (environmental awareness, financial benefit) and
disadvantages (disease risks, disturbance of natural behavior) for the
conservation of the gorillas.
Unlike the western lowland gorilla, there are few eastern gorillas in
Antwerp Zoo is the only zoo outside the native range of the
species that has eastern lowland 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 Tayna
Nature Reserve, and mountain gorillas at the Senkwekwe Center in
Virunga National Park.
^ Groves, C.P. (2005). Wilson, D.E.; Reeder, D.M., eds.
of the World: A Taxonomic and Geographic Reference (3rd ed.).
Baltimore: Johns Hopkins University Press. pp. 181–182.
ISBN 0-801-88221-4. OCLC 62265494.
^ Plumptre, A.; Robbins, M.; Williamson, E. A. (2016). "Gorilla
IUCN Red List
IUCN Red List of Threatened Species. IUCN. 2016:
e.T39994A17964126. Retrieved 5 September 2016.
^ "Gorillas on Thin Ice". United Nations Environment Programme. 15
January 2009. Archived from the original on 18 May 2016. Retrieved 19
May 2010. : "The Eastern Lowland
Gorilla population in the DRC
has plummeted dramatically over the last 10 years, with probably only
about 5,000 of the formerly 17,000 animals remaining."
^ "The Eastern
Gorilla listed on Red List of Endangered
IUCN". CBSnews. AP. September 4, 2016. Retrieved September 4,
^ a b "Four out of six great apes one step away from extinction –
IUCN Red List". 4 September 2016.
^ Taylor, Andrea Beth; Goldsmith, Michele Lynn (2003). Gorilla
biology: a multidisciplinary perspective. Cambridge University Press.
p. 13. ISBN 978-0-521-79281-3.
^ Williamson, E.A. and Butynski, T.M. (2013)
Gorilla gorilla. In:
Butynski, T.M. (Ed) The Mammals of Africa. Volume 6. Elsevier Press.
^ Burnie D and Wilson DE (Eds.), Animal: The Definitive Visual Guide
to the World's Wildlife. DK Adult (2005), ISBN 0789477645
Gorilla Biology: A Multidisciplinary Perspective
^ Wood, Gerald L. (1983) The Guinness Book of
Animal Facts and Feats.
Sterling Pub Co Inc. ISBN 978-0-85112-235-9
^ Fossey, Dian (2000). Gorillas in the Mist. Houghton Mifflin Books.
Gorilla Fund: The GRACE Center for Rescued Gorillas.
Retrieved 16 August 2013
^ Senkwekwe Orphan Mountain
Gorilla Center. Retrieved 16 August 2013
Wikimedia Commons has media related to
Animal Diversity Web:
Eastern Gorilla: Mountain
Gorilla and Grauer's Gorilla
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