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The '''eastern lowland gorilla''' (''Gorilla beringei graueri'') also known as the '''Grauer's gorilla''' is a subspecies of [[eastern gorilla]] endemic to the mountainous forests of eastern [[Democratic Republic of the Congo]]. Important populations of this gorilla live within the [[Kahuzi-Biéga National Park|Kahuzi-Biega]] and [[Maiko National Park]]s and their adjacent forests, the Tayna Gorilla Reserve, the Usala forest and on the [[Itombwe Massif]].
'''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-Biéga National Park|Kahuzi-Biega]] and [[Maiko National Park]]s 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 [[Silverback|silver at the back]] as the animal matures. There are many more [[western lowland gorilla]]s than the eastern variety; compared to a possible total of over 100,000 western lowland gorillas, there are only about 5,000 eastern lowland gorillas in the wild.<ref name="">{{Cite web | url = http://news.nationalgeographic.com/news/2004/03/0331_040331_easterngorillas.html | title = Eastern lowland gorilla numbers plunge to 5,000, study says | author = Pickrell, J. | publisher = [[National Geographic (magazine)|National Geographic]] News | date = 2004-03-21}}</ref> Outside the native range, only two females are in captivity at the [[Antwerp Zoo]] in [[Belgium]].<ref name="Prince-Hughes66">{{cite book |title= Songs of the Gorilla Nation|last= Prince-Hughes|first= Dawn|authorlink= Dawn Prince-Hughes|year= 1987|publisher= Harmony|location= |isbn=1-4000-5058-8|page= 66|pages= |url= }}</ref><ref name="Zootierliste">{{Cite web | url = http://www.zootierliste.de/en/?klasse=1&ordnung=108&familie=10819&art=1071201 | title = Zootierliste}}</ref>
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 [[Silverback|silver at the back]] as the animal matures. There are many more [[western lowland gorilla]]s than the eastern variety; compared to a over 100,000 western lowland gorillas, there are only about 5,000 eastern lowland gorillas in the wild.<ref name="">{{Cite web | url = http://news.nationalgeographic.com/news/2004/03/0331_040331_easterngorillas.html | title = Eastern lowland gorilla numbers plunge to 5,000, study says | author = Pickrell, J. | publisher = [[National Geographic (magazine)|National Geographic]] News | date = 2004-03-21}}</ref> Outside the native range, only two females are in captivity at the [[Antwerp Zoo]] in [[Belgium]].<ref name="Prince-Hughes66">{{cite book |title= Songs of the Gorilla Nation|last= Prince-Hughes|first= Dawn|authorlink= Dawn Prince-Hughes|year= 1987|publisher= Harmony|location= |isbn=1-4000-5058-8|page= 66|pages= |url= }}</ref><ref name="Zootierliste">{{Cite web | url = http://www.zootierliste.de/en/?klasse=1&ordnung=108&familie=10819&art=1071201 | title = Zootierliste}}</ref>


==Physical description==
==Physical description==
Eastern lowland gorillas are the largest subspecies of [[gorilla]] and the largest living primates.<ref name="worldwildlife" /> Males weigh {{convert|163|kg|lb|abbr=on}} on average while females usually weigh half as much.<ref>{{cite book|last=Tuttle|first=Russell H.|title=Apes of the World: Their Social Behavior, Communication, Mentality and Ecology|year=1986|publisher=William Andrew |isbn=0815511043}}</ref> Males have a standing height of {{Convert|1.69|m}} on average and females stand at {{Convert|1.60|m}} or less.
Grauer's gorillas are the largest subspecies of [[gorilla]] and the largest living primates.<ref name="worldwildlife" /> Males weigh {{convert|163|kg|lb|abbr=on}} on average while females usually weigh half as much.<ref>{{cite book|last=Tuttle|first=Russell H.|title=Apes of the World: Their Social Behavior, Communication, Mentality and Ecology|year=1986|publisher=William Andrew |isbn=0815511043}}</ref> Males have a standing height of {{Convert|1.69|m}} on average and females stand at {{Convert|1.60|m}} 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 {{convert|270|kg|lb}}.<ref>{{cite book|last=Miller|first=Patricia|title=Gorillas|year=1997|isbn=0919879896|pages=64 |url=http://books.google.com.mx/books?id=wSXgVKUYpvgC&pg=PA8&dq=adult+gorilla+weighs&hl=en&sa=X&ei=d5BNT5_lH4rv0gHjrLjAAg&redir_esc=y#v=onepage&q&f=false}}</ref> 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 {{convert|250|kg|lb}}.<ref>{{cite book|last=Leonard|first=Mary D. |title=Animals Always: 100 years at the Saint Louis Zoo |year=2009|pages=208|url=http://books.google.com.mx/books?id=zBgWXLW-Yk8C&pg=PT79&lpg=PT79&dq=David+Willoughby+phil+gorilla&source=bl&ots=7cVcIYqSoB&sig=-_xVwyNL7X3QIMd3qzz-VSPhyKk&hl=es-419&sa=X&ei=ThTyT7W1EuHL2QXB8o2DAg&ved=0CEcQ6AEwAA#v=onepage&q=David%20Willoughby%20phil%20gorilla&f=false}}</ref> Phil's recorded measurements were: height {{convert|1.7|m|ft|abbr=on}}, bust {{convert|182|cm|in|abbr=on}}, neck {{convert|91.5|cm|in|abbr=on}}, and wrist {{convert|25.4|cm|in|abbr=on}}.<ref>Dobroruka. L. J.: Poloopice an opice (Prosimians and Apes), 2nd ed., Prague, 1983, pp.175-6</ref>
Gorillas living in zoos are usually heavier than those in the wild, since they get less exercise and can weigh as much as {{convert|270|kg|lb}}.<ref>{{cite book|last=Miller|first=Patricia|title=Gorillas|year=1997|isbn=0919879896|pages=64 |url=http://books.google.com.mx/books?id=wSXgVKUYpvgC&pg=PA8&dq=adult+gorilla+weighs&hl=en&sa=X&ei=d5BNT5_lH4rv0gHjrLjAAg&redir_esc=y#v=onepage&q&f=false}}</ref> 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 {{convert|250|kg|lb}}.<ref>{{cite book|last=Leonard|first=Mary D. |title=Animals Always: 100 years at the Saint Louis Zoo |year=2009|pages=208|url=http://books.google.com.mx/books?id=zBgWXLW-Yk8C&pg=PT79&lpg=PT79&dq=David+Willoughby+phil+gorilla&source=bl&ots=7cVcIYqSoB&sig=-_xVwyNL7X3QIMd3qzz-VSPhyKk&hl=es-419&sa=X&ei=ThTyT7W1EuHL2QXB8o2DAg&ved=0CEcQ6AEwAA#v=onepage&q=David%20Willoughby%20phil%20gorilla&f=false}}</ref> Phil's recorded measurements were: height {{convert|1.7|m|ft|abbr=on}}, bust {{convert|182|cm|in|abbr=on}}, neck {{convert|91.5|cm|in|abbr=on}}, and wrist {{convert|25.4|cm|in|abbr=on}}.<ref>Dobroruka. L. J.: Poloopice an opice (Prosimians and Apes), 2nd ed., Prague, 1983, pp.175-6</ref>
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==Habitat and ecology==
==Habitat and ecology==


Gorillas must eat frequently due to their large size and therefore must spend long hours feeding every day. Gorillas are stable [[apes]] as they travel together for months and years at a time, much like the structure of a family.<ref name="yog2009">{{cite web|title=Eastern lowland gorilla |url=http://www.yog2009.org/index.php?view=article&catid=46%3Agorillaspecies&id=62%3Aelgspeciesinfo&option=com_content&Itemid=70 |work=Year of the Gorilla: 2009|accessdate=2 November 2012}}</ref> Gorillas travel in permanent groups because of their foliage diet, which allows them to travel. In comparison to the Western Gorillas, the groupings of eastern gorillas are usually much larger and split into temporary groups much less frequently.<ref name="yog2009"/>
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.<ref name="yog2009">{{cite web|title=Eastern lowland gorilla |url=http://www.yog2009.org/index.php?view=article&catid=46%3Agorillaspecies&id=62%3Aelgspeciesinfo&option=com_content&Itemid=70 |work=Year of the Gorilla: 2009|accessdate=2 November 2012}}</ref>. In comparison to the Western Gorillas, groups of Grauer's gorillas are usually larger.<ref name="yog2009"/>


The eastern lowland 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 eastern lowland 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]].<ref name="yog2009"/>
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]].<ref name="yog2009"/>


⚫
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.<ref name="nellemann"/>
⚫
The eastern lowland gorilla has a varied diet including plants, fruits, seeds, leaves, stems and bark as well as small insects such as ants and termites.<ref name="yog2009"/> Although they occasionally feed on ants, it is only a minor part of their diet. In comparison to western lowland gorillas, found in low altitude forests, eastern lowland gorillas travel much less and increase their consumption of herbaceous vegetation.<ref name="yog2009"/>

⚫
Grauer's gorilla has a varied plants diet including fruits, leaves, stems and bark as well as small insects such as ants and termites.<ref name="yog2009"/> 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 ==
== Behaviour ==
Eastern lowland gorillas tend to be sociable and very peaceful, living in groups of five to 30. A group usually consists of one silverback and a few subdominant males. Silverbacks are the strong, dominant troop leaders (see [[alpha male]]). They are in charge of leading the group to food and protecting the group from danger. Males will slowly begin to leave their original group when they reach maturity, usually traveling with a group of other males for a few years before being able to attract females to form a new group.
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.


Very little is known about the social behaviour, history and ecology of the eastern lowland gorillas primarily because of the civil war taking place in the [[Democratic Republic of the Congo]] making it impossible for researchers to get the data necessary. However, some aspects of social behaviour have been studied. For example, gorillas form [[Harem (zoology)|harems]] with usually includes two full-grown males, as opposed to one, which was previously believed to be the group structure for this gorilla subspecies.<ref name="yog2009"/> Evidence shows that one third of gorilla groups in East Africa have two grown males in their group.<ref name="yog2009"/>
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 [[Harem (zoology)|harems]] with may include two full-grown males.<ref name="yog2009"/> One third of gorilla groups in East Africa have two grown males in their group.<ref name="yog2009"/>


Most primates are bonded together by the relationship between females, a pattern also seen in many human families. In the eastern lowland gorilla population, the group is held together between each individual female and the [[silverback]], much like the historically traditional view of a heterosexual [[Homo sapiens]] family structure. Once the gorillas reach maturity, both females and males usually leave the group.<ref name="yog2009"/> Females usually join another group or a single lone young adult male, whereas males typically remain together until they find females and establish their own groups.<ref>{{cite journal|last=Yamagiwa|first=J|title=Bushmeat poaching and the conservation crisis in Kahuzi-Biega National Park, Democratic Republic of the Congo|journal=Journal of Sustainable Forestry|year=2003|volume=16 |pages=115–135|doi=10.1300/j091v16n03_06}}</ref> It is commonly believed that the structure of the gorilla group is to prevent predation.<ref>{{cite journal|last=Yamagiwa|first=J.|author2=N. Mwanza |author3=A. Spangenberg |author4=T. Maruhashi |author5=T. Yumoto |author6=A. Fischer |author7=B. Steinhauer |title=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 |journal=Biologial Conservation |volume=64|pages=83–89 |doi=10.1016/0006-3207(93)90386-f}}</ref>
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.<ref name="yog2009"/> 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.<ref>{{cite journal|last=Yamagiwa|first=J|title=Bushmeat poaching and the conservation crisis in Kahuzi-Biega National Park, Democratic Republic of the Congo|journal=Journal of Sustainable Forestry|year=2003|volume=16 |pages=115–135|doi=10.1300/j091v16n03_06}}</ref> It is commonly believed that the structure of the gorilla group is to prevent predation.<ref>{{cite journal|last=Yamagiwa|first=J.|author2=N. Mwanza |author3=A. Spangenberg |author4=T. Maruhashi |author5=T. Yumoto |author6=A. Fischer |author7=B. Steinhauer |title=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 |journal=Biologial Conservation |volume=64|pages=83–89 |doi=10.1016/0006-3207(93)90386-f}}</ref>


=== Reproduction ===
=== Reproduction ===
A female will give birth to twins or a single infant after a gestation period of about 8½ months. They breastfeed for about 12 months. 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 11 to 12 years old.
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==
==Conservation and threats==


[[File:Gorilla beringei graueri01.jpg|thumb|upright|Male eastern lowland gorilla]]
[[File:Gorilla beringei graueri01.jpg|thumb|upright|Male Grauer's gorilla]]


The primary causes of habitat loss directly cause the decline in eastern lowland populations. These primary causes are: the killing of gorillas for [[bushmeat]], 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]].<ref name="nellemann"/> Widespread artisanal mining activities (often controlled by rebel militias) are the major source of hunting pressure for gorillas and other wildlife. The eastern lowland gorilla is also suffering a range reduction in some areas due to an expanding human population.
The primary cause of the decline in Grauer's gorilla populations is poaching for bushmeat. Other reasons for killing gorillas are: the killing of gorillas for [[bushmeat]], 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]].<ref name="nellemann"/> 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 eastern lowland gorilla's survival include: logging, mining, civil unrest and hunting.<ref name="worldwildlife">{{cite web|title=Eastern lowland gorilla |url=http://worldwildlife.org/species/eastern-lowland-gorilla|publisher=World Wildlife Fund|accessdate=23 October 2012}}</ref>
Threats to the Grauer's gorilla's survival include: poaching, mining, civil unrest and agriculture.<ref name="worldwildlife">{{cite web|title=Eastern lowland gorilla |url=http://worldwildlife.org/species/eastern-lowland-gorilla|publisher=World Wildlife Fund|accessdate=23 October 2012}}</ref>


Civil unrest in the Democratic Republic of Congo has resulted in a decline in eastern lowland gorillas as well as mountain gorillas in this region. The region inhabited by eastern lowland gorilla has decreased from 8,100 square miles to 4,600 square miles in the past 50 years.<ref name="worldwildlife"/> 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.<ref name="worldwildlife"/> In the mid-1990s, the population was recorded to nearly 17,000 gorillas.
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.<ref name="worldwildlife"/> 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.<ref name="worldwildlife"/> In the mid-1990s, the population was recorded to nearly 17,000 gorillas.


===Civil war===
===Civil war===


The civil war taking place in the Democratic of the Congo means military groups remain within 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.<ref name="jstor3074721">{{cite journal|last=Vogel|first=Gretchen|title=Conflict in Congo Threatens Bonobos and Rare Gorillas|journal=Science |date=Mar 31, 2000 |volume=287|issue=5462|pages=2386–2387|url=http://www.jstor.org/stable/3074721|accessdate=2012-09-26|doi=10.1126/science.287.5462.2386}}</ref> 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.<ref name="jstor3074721"/>
The civil war in the Democratic 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.<ref name="jstor3074721">{{cite journal|last=Vogel|first=Gretchen|title=Conflict in Congo Threatens Bonobos and Rare Gorillas|journal=Science |date=Mar 31, 2000 |volume=287|issue=5462|pages=2386–2387|url=http://www.jstor.org/stable/3074721|accessdate=2012-09-26|doi=10.1126/science.287.5462.2386}}</ref> 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.<ref name="jstor3074721"/>


[[Conservation groups]] negotiated with rebels who control the eastern Democratic Republic of the Congo to re-arm the park guards <ref name="jstor3074721"/> After the war began, government funding of the park was stopped. Conservation groups,<ref>[http://www.yog2009.org/index.php?view=article&catid=46%3Agorillaspecies&id=62%3Aelgspeciesinfo&option=com_content&Itemid=70 WWF]</ref> International Gorilla Conservation Program and Deutsche Gesellschaft für Technische Zusammenarbeit (German development agency) have funded the guards for the past several years <ref name="jstor3074721"/>
[[Conservation groups]] negotiated with rebels who control the eastern Democratic Republic of the Congo to re-arm the park guards <ref name="jstor3074721"/> After the war began, government funding of the park was stopped. Conservation groups,<ref>[http://www.yog2009.org/index.php?view=article&catid=46%3Agorillaspecies&id=62%3Aelgspeciesinfo&option=com_content&Itemid=70 WWF]</ref> International Gorilla Conservation Program and Deutsche Gesellschaft für Technische Zusammenarbeit (German development agency) have funded the guards for the past several years <ref name="jstor3074721"/>
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===Bushmeat===
===Bushmeat===


[[Bushmeat]] is useful for displaced peoples residing in the region affected by the civil war, militias groups and loggers and miners.<ref>Wilkie and Carpenter, 1999; Fa et al., 2000; Brashares et al., 2004; Ryan and Bell, 2005; Poulsen et al., 2009)</ref> Surveys have shown that [[great apes]], [[chimpanzees]] and [[bonobos]] comprise 0.5-2% of the meat found in bushmeats markets.<ref name="nellemann"/> Some researchers have found that up to 5 million metric tons of bushmeat are traded annually.<ref name="nellemann"/> This has a detrimental affect on the eastern lowland gorilla populations because of their slow rate of reproduction and their already struggling population.<ref name="nellemann"/> 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.<ref name="nellemann"/>
[[Bushmeat]] is eaten by displaced peoples residing in the region affected by the civil war, militias groups and loggers and miners.<ref>Wilkie and Carpenter, 1999; Fa et al., 2000; Brashares et al., 2004; Ryan and Bell, 2005; Poulsen et al., 2009)</ref> Surveys have shown that [[great apes]], [[chimpanzees]] and [[bonobos]] comprise 0.5-2% of the meat found in bushmeats markets.<ref name="nellemann"/> Some researchers have found that up to 5 million metric tons of bushmeat are traded annually.<ref name="nellemann"/> This has a detrimental affect on the eastern lowland gorilla populations because of their slow rate of reproduction and their already struggling population.<ref name="nellemann"/> 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.<ref name="nellemann"/>

⚫
Banana plantations have been affected by gorillas. Gorillas rarely eat the banana fruits, but they do 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.<ref name="nellemann"/>


===Park conservation===
===Park conservation===

Revision as of 22:59, 14 March 2016

Eastern lowland gorilla
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Primates
Family:
Hominidae
Genus:
Gorilla
Species:
G. beringei
Subspecies:
G. b. graueri
Trinomial name
Gorilla beringei graueri
(Matschie, 1914)
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 a over 100,000 western lowland gorillas, there are only about 5,000 eastern lowland gorillas in the wild.[2] Outside the native range, only two females are in captivity at the Antwerp Zoo in Belgium.[3][4]

Physical description

Grauer's gorillas are the largest subspecies of gorilla and the largest living primates.[5] Males weigh 163 kg (359 lb) on average while females usually weigh half as much.[6] 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).[7] 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).[8] 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).[9]

Habitat and ecology

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.[10]. In comparison to the Western Gorillas, groups of Grauer's gorillas are usually larger.[10]

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.[10]

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.[11]

Grauer's gorilla has a varied plants diet including fruits, leaves, stems and bark as well as small insects such as ants and termites.[10] 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

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.[10] One third of gorilla groups in East Africa have two grown males in their group.[10]

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.[10] 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.[12] It is commonly believed that the structure of the gorilla group is to prevent predation.[13]

Reproduction

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

Male Grauer's gorilla

The primary cause of the decline in Grauer's gorilla populations is poaching for bushmeat. Other reasons for killing gorillas are: the killing of gorillas for bushmeat, 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.[11] 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.[5]

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.[5] 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.[5] In the mid-1990s, the population was recorded to nearly 17,000 gorillas.

Civil war

The civil war in the Democratic 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.[14] 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.[14]

Conservation groups negotiated with rebels who control the eastern Democratic Republic of the Congo to re-arm the park guards [14] After the war began, government funding of the park was stopped. Conservation groups,[15] International Gorilla Conservation Program and Deutsche Gesellschaft für Technische Zusammenarbeit (German development agency) have funded the guards for the past several years [14]

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.[11] 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.[11] 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"[11] Private companies have been found to trade weapons for resources or provide access to weapons through subsidiary companies.[11]

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.[11] 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.[11] Once the Congo war began in 1996, 500,000 refugees remained, putting pressure on the natural resources, including the eastern lowland gorilla.

Bushmeat

Bushmeat is eaten by displaced peoples residing in the region affected by the civil war, militias groups and loggers and miners.[16] Surveys have shown that great apes, chimpanzees and bonobos comprise 0.5-2% of the meat found in bushmeats markets.[11] Some researchers have found that up to 5 million metric tons of bushmeat are traded annually.[11] This has a detrimental affect on the eastern lowland gorilla populations because of their slow rate of reproduction and their already struggling population.[11] 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.[11]

Park conservation

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.[11] 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 [11] Illegal extraction of resources from the Virunga National Park has been reduced by policing transportation across borders.[11] This has reduced the financial input available to the militias in the region.[11] 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.[11] On July 22, 2007, 10 gorillas were killed in retaliation to the park rangers for interfering with the exportation of illegal resources such as wood.[11]

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.[11] Gorillas are also threatened directly by militia groups because of the prevalence of booby traps placed randomly throughout the forest.[11] Although the eastern lowland gorilla population is affected directly from violence caused by militia groups, their population is endangered mainly from the extraction of natural resources disrupting their habitat.

Conservation groups negotiated with rebels who control the eastern Democratic Republic of the Congo to re-arm the park guards.[14] 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.[14]

Logging

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.

References

  1. ^ Template:IUCN2008
  2. ^ Pickrell, J. (2004-03-21). "Eastern lowland gorilla numbers plunge to 5,000, study says". National Geographic News.
  3. ^ Prince-Hughes, Dawn (1987). Songs of the Gorilla Nation. Harmony. p. 66. ISBN 1-4000-5058-8.
  4. ^ "Zootierliste".
  5. ^ a b c d "Eastern lowland gorilla". World Wildlife Fund. Retrieved 23 October 2012.
  6. ^ Tuttle, Russell H. (1986). Apes of the World: Their Social Behavior, Communication, Mentality and Ecology. William Andrew. ISBN 0815511043.
  7. ^ Miller, Patricia (1997). Gorillas. p. 64. ISBN 0919879896.
  8. ^ Leonard, Mary D. (2009). Animals Always: 100 years at the Saint Louis Zoo. p. 208.
  9. ^ Dobroruka. L. J.: Poloopice an opice (Prosimians and Apes), 2nd ed., Prague, 1983, pp.175-6
  10. ^ a b c d e f g "Eastern lowland gorilla". Year of the Gorilla: 2009. Retrieved 2 November 2012.
  11. ^ 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.
  12. ^ 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.
  13. ^ 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.
  14. ^ 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.
  15. ^ WWF
  16. ^ Wilkie and Carpenter, 1999; Fa et al., 2000; Brashares et al., 2004; Ryan and Bell, 2005; Poulsen et al., 2009)
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