Western Gorilla
Encyclopedia
The western gorilla is a great ape and the most populous species of the genus Gorilla
.
subspecies (G. g. gorilla) whose population is approximately 95,000 individuals http://www.iucnredlist.org/apps/redlist/details/9404/0. There are fewer than 300 of the only other western gorilla subspecies, the Cross River gorilla
(G. g. diehli).
Fruit
forms a large part of the western gorilla's diet and they will travel further each day in search of fruiting trees than their eastern relatives. The distance that gorillas travel in the forest each day while they are searching for fruit trees varies between one and four kilometres. A group's home range may be as large as 30 square kilometres but is not actively defended.
Wild western gorillas are known to use tools.
A study published in 2007 in the American Journal of Primatology
announced the discovery of the fighting back against possible threats from humans. They "found several instances of gorillas throwing sticks and clumps of grass." This is unusual, because gorillas usually flee and rarely charge when encountered by humans.
lists the western gorilla as critically endangered
, the most severe denomination next to global extinction, on its 2007 Red List of Threatened Species
. It is thought that the Ebola virus
might be depleting western gorilla populations to a point where it might become impossible for them to recover, and the virus decimated populations in protected areas by one-third from 1992 to 2007. Poaching
, commercial logging and civil war
s in the countries that compose the western gorillas' habitat
are also threats.
In the 1980s, a census taken of the gorilla populations in equatorial Africa
was thought to be 100,000. Researchers adjusted the figure after years of poaching and deforestation had reduced the population to approximately 50,000.
Surveys conducted by the Wildlife Conservation Society
in 2006 and 2007 found more than 100,000 previously unreported gorillas have been living in the swamp forests of Lake Tele
Community Reserve and in neighbouring Marantaceae (dryland) forests in the Republic of the Congo.
With the new discovery, the current population of western lowland gorillas could be around 150,000–200,000. However, the gorilla remains vulnerable to Ebola
, deforestation
, and poaching
.
Estimates on the number of Cross River gorillas remaining is about 280 in the wild, concentrated in approximately 11 locations. Recent genetic research and field surveys suggest that these locations are linked by the occasional migration of individual gorillas. The nearest population of western lowland gorilla is some 250 km away. Both loss of habitat and intense hunting for bushmeat
have contributed to the decline of this subspecies. A conservation plan for the Cross River gorilla was published in 2007 and outlines the most important actions necessary to preserve this subspecies. Richard Black of the BBC has reported that the government of Cameroon has created the Takamanda National Park on the border with Nigeria, as an attempt to protect these gorillas. The park now forms part of an important trans-boundary protected area with Nigeria’s Cross River National Park, safeguarding an estimated 115 gorillas—a third of the Cross River gorilla population—along with other rare species. The hope is that the gorillas should be able to move between the Takamanda reserve in Cameroon over the border to Nigeria's Cross River National Park.
Gorilla
Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies...
.
Taxonomy
Nearly all of the individuals of this taxon belong to the western lowland gorillaWestern Lowland Gorilla
The western lowland gorilla is a subspecies of the western gorilla that lives in montane, primary, and secondary forests and lowland swamps in Angola, Cameroon, Central African Republic, Congo, Democratic Republic of the Congo, Equatorial Guinea and Gabon. It is the gorilla usually found in zoos...
subspecies (G. g. gorilla) whose population is approximately 95,000 individuals http://www.iucnredlist.org/apps/redlist/details/9404/0. There are fewer than 300 of the only other western gorilla subspecies, the Cross River gorilla
Cross River Gorilla
The Cross River gorilla is a subspecies of the western gorilla that can be found on the border between Nigeria and Cameroon, in both tropical and subtropical moist broadleaf forests which are also home to the Nigeria-Cameroon Chimpanzee, another subspecies of great ape...
(G. g. diehli).
Appearance
The western gorilla is slightly smaller, lighter, more slender and clearer dyed than its eastern cousin. The western lowland gorilla can be brown or greyish with a yellowish forehead. It also has an overhanging tip on its nose, which the eastern gorilla does not have. Males measure 160–170 cm and weigh 140–160 kg. Females measure 120–140 cm and weigh 60–80 kg. The western gorilla is the smaller species of the gorilla. The Cross River gorilla differs from the western lowland gorilla in both skull and tooth dimensions. It is also about 10–15 cm taller and 20–35 kg heavier, but still smaller and lighter than the mountain gorilla and the eastern lowland gorilla, latter the largest subspecies of the gorilla and the largest living primate.Behavior and ecology
Western gorillas live in groups that vary in size between 2 and 20 individuals, composed of at least one male, several females and their offspring. A dominant male silverback heads the group, with younger males usually leaving the group when they reach maturity. Females transfer to another group before breeding, which begins at eight to nine years old; they care for their young infant for the first three to four years of its life. There is therefore a long interval between births, which partly explains the slow population growth rates that make the western gorilla so vulnerable to poaching. Due to the long gestation time, long period of parental care, and infant mortality, a female gorilla will only give birth to an offspring that survives to maturity every six to eight years. Gorillas are long-lived and may survive for as long as 40 years in the wild.Fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
forms a large part of the western gorilla's diet and they will travel further each day in search of fruiting trees than their eastern relatives. The distance that gorillas travel in the forest each day while they are searching for fruit trees varies between one and four kilometres. A group's home range may be as large as 30 square kilometres but is not actively defended.
Wild western gorillas are known to use tools.
A study published in 2007 in the American Journal of Primatology
American Journal of Primatology
The American Journal of Primatology is a peer-reviewed scientific journal and the official journal of the American Society of Primatologists. It was established in 1981. The journal currently publishes 12 issues per year plus a supplementary issue detailing the program of the society's annual...
announced the discovery of the fighting back against possible threats from humans. They "found several instances of gorillas throwing sticks and clumps of grass." This is unusual, because gorillas usually flee and rarely charge when encountered by humans.
Status
The World Conservation UnionWorld Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
lists the western gorilla as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
, the most severe denomination next to global extinction, on its 2007 Red List of Threatened Species
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. It is thought that the Ebola virus
Ebola virus
Ebola virus causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fever. EBOV is a Select Agent, World Health Organization Risk Group 4 Pathogen , National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen,...
might be depleting western gorilla populations to a point where it might become impossible for them to recover, and the virus decimated populations in protected areas by one-third from 1992 to 2007. Poaching
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
, commercial logging and civil war
Civil war
A civil war is a war between organized groups within the same nation state or republic, or, less commonly, between two countries created from a formerly-united nation state....
s in the countries that compose the western gorillas' habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
are also threats.
In the 1980s, a census taken of the gorilla populations in equatorial Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
was thought to be 100,000. Researchers adjusted the figure after years of poaching and deforestation had reduced the population to approximately 50,000.
Surveys conducted by the Wildlife Conservation Society
Wildlife Conservation Society
The Wildlife Conservation Society based at the Bronx Zoo was founded in 1895 as the New York Zoological Society and currently manages some of wild places around the world, with over 500 field conservation projects in 60 countries, and 200 scientists on staff...
in 2006 and 2007 found more than 100,000 previously unreported gorillas have been living in the swamp forests of Lake Tele
Lake Tele
Lake Tele is a freshwater lake located in the north-east of the Republic of the Congo. It is located at .Lake Tele has often been mentioned as the home of the Mokèlé-mbèmbé , and is also allegedly the spot where pygmies killed and ate one of the creatures in about 1959...
Community Reserve and in neighbouring Marantaceae (dryland) forests in the Republic of the Congo.
With the new discovery, the current population of western lowland gorillas could be around 150,000–200,000. However, the gorilla remains vulnerable to Ebola
Ebola
Ebola virus disease is the name for the human disease which may be caused by any of the four known ebolaviruses. These four viruses are: Bundibugyo virus , Ebola virus , Sudan virus , and Taï Forest virus...
, deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
, and poaching
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
.
Estimates on the number of Cross River gorillas remaining is about 280 in the wild, concentrated in approximately 11 locations. Recent genetic research and field surveys suggest that these locations are linked by the occasional migration of individual gorillas. The nearest population of western lowland gorilla is some 250 km away. Both loss of habitat and intense hunting for bushmeat
Bushmeat
Bushmeat initially referred to the hunting of wild animals in West and Central Africa and is a calque from the French viande de brousse. Today the term is commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas,...
have contributed to the decline of this subspecies. A conservation plan for the Cross River gorilla was published in 2007 and outlines the most important actions necessary to preserve this subspecies. Richard Black of the BBC has reported that the government of Cameroon has created the Takamanda National Park on the border with Nigeria, as an attempt to protect these gorillas. The park now forms part of an important trans-boundary protected area with Nigeria’s Cross River National Park, safeguarding an estimated 115 gorillas—a third of the Cross River gorilla population—along with other rare species. The hope is that the gorillas should be able to move between the Takamanda reserve in Cameroon over the border to Nigeria's Cross River National Park.