Post by Jeff on Apr 23, 2008 19:05:31 GMT -5
Historical Background
"None of the three great apes is considered ancestral to modern man, Homo sapiens, but they remain the only other type of extant primate with which human beings share such close physical characteristics. From them we may learn much concerning the behavior of our earliest primate prototypes, because behavior, unlike bones, teeth, or tools, does not fossilize.
Several million years ago the chimpanzee and gorilla lines had already separated from one another, and the orangutan line even earlier than that. Throughout the eighteenth century there remained a considerable amount of confusion in distinguishing between orangutans, chimpanzees, and gorillas. The orangutan was the first to be recognized as a distinct genus -- only because of its remote habitat in Asia. It was not until 1847, on the basis of a single skull from Gabon, that the gorilla was confirmed as a separate genus from the chimpanzee." (Fossey, 1983)
Subspecies of Gorillas
Just as there are separate subspecies among orangutan and chimpanzee, there are separate suspecies of gorilla, also with morphological variations related probably primarily to habitat.
The gorillas, previously considered a single species, were recently divided into two species and five subspecies. The eastern gorilla (Gorilla beringei) includes the mountain gorilla (Gorilla beringei beringei) of the Virunga Volcanoes area of Rwanda, Uganda and the Democratic Republic of Congo, the yet unnamed, but distinct, population of Uganda's Bwindi (Impenetrable) Forest, and the eastern lowland gorilla (Gorilla beringei graueri). Western Africa is home to at least two additional taxa, the western lowland gorilla (Gorilla gorilla gorilla) and the Cross River gorilla (Gorilla gorilla diehli). The mountain, Bwindi and Cross River gorilla populations all number only in the hundreds and are considered critically endangered. (Once and Future Primate Order, Conservation International, 5 April 2000)
In western Africa there remain approximately 94,000 western lowland gorilla (Gorilla gorilla gorilla ) in the wild, but recent surveys indicate a decline of up to 56 percent across their range, due to poaching and disease. In areas hard hit by the Ebola virus, over 90 percent of great apes have been killed. It is this subspecies most frequently seen in captivity and mounted in museum collections.
Some 1000 miles to the east within the Virunga Volcanoes of Zaire, Uganda, and Rwanda live the last surviving mountain gorillas (Gorilla gorilla beringei ). The Virunga population were the subjects of Dian Fossey's field study. According to a recent census of mountain gorillas in the Virunga montane forests, led by the WWF-funded International Gorilla Conservation Program, about 380 mountain gorillas remain in the wild. This is a 17 percent increase in the population based on the count of 324 mountain gorillas more than a decade ago. The Bwindi gorilla population — previously classified as mountain gorillas by some scientists — numbers approximately 325 animals in the Bwindi Impenetrable National Park in Uganda. No mountain gorillas live in captivity.
Another recognized subspecies is known as Grauer's gorillas or the eastern lowland gorilla (Gorilla beringei graueri). An estimated population of 16,000 eastern lowland gorillas remain in the lowland and Albertine Rift montane forests of Democratic Republic of Congo, where they have been long-time victims of poaching in a historically war-torn area (WWF 2005). These figures are far higher than previously reported, both as a result of more sophisticated calculations on the basis of estimates of density, and of area of available habitat, and because of exciting new findings of gorillas in huge areas of west Africa where they were not previously suspected to be (Harcourt 1996). While the high numbers are good news, most live outside protected areas, and calculations of rate of forest disappearance in Africa indicate that numbers will crash in the next 150 years (Harcourt 1996).
A recent report from Conservation International states:
"The world population of the Endangered eastern lowland gorilla (Gorilla beringei graueri), found almost exclusively in eastern Democratic Republic of Congo (DRC), has plummeted by more than 70 percent in the past decade. Scientists estimate that fewer than 5,000 individuals remain, down sharply from 17,000 in 1994." (Conservation International, March 2004)
A subspecies of eastern gorilla, the eastern lowland gorilla now inhabits just 13 percent of its historic range. The eastern lowland gorilla is located approximately 600 miles from the nearest population of western lowland gorillas (WWF 2005). In 2005, there were only two female eastern lowland gorillas living in captivity at the Antwerp Zoo (ISIS Abstracts, February 2005).
The Cross River gorilla, which differs from the western lowland gorilla in skull and tooth dimensions, is restricted to the forested hills on the Nigerian-Cameroon border (WWF 2005). "The Cross River gorilla is a good example of why we must be very careful not to neglect possible diversity. In the nick of time we have realized these gorillas are distinct, just before it is finally too late to save them from oblivion," said Dr. John F. Oates, primatologist with Hunter College - CUNY, and co-author with Esteban Sarmiento of the American Museum of Natural History, of the re-description of the Cross River gorilla." (Primates on the Brink, Conservation International 10 January 2000). The Cross River gorilla population is estimated to be 200 animals, making it one of the rarest apes in the world.
There is one Cross River gorilla living in the Limbe Wildlife Centre (LWC) near Douala, in the West of Cameroon. The LWC takes in rescued animals, often orphans of the pet and bushmeat trades.
[Population estimates were updated in 2005, based on new information from Conservation International and the World Wildlife Fund
Distribution
The distribution of gorillas in Africa is discontinuous. The western lowland gorilla (Gorilla gorilla gorilla ) is found in south-east Nigeria, Cameroon, Equatorial Guinea, Gabon, Congo (Brazzaville), and the Central African Republic. A wide gap exists between this large area of distribution and the two other subspecies, each with extremely limited ranges; the mountain gorilla (Gorilla beringei beringei ) from the Virunga Volcanoes and the Bwindi Forest at altitudes of 2,100-3,650m (7-12,000 ft) on the Zaire-Rwanda border; and the eastern lowland gorilla (Gorilla beringei graueri ) from Zaire, to the west of Lake Tanganyika and Lake Edward, from the lower altitudes of 760-2255m (2500-7400 ft). See the distribution map (based on Harcourt 1996).
"None of the three great apes is considered ancestral to modern man, Homo sapiens, but they remain the only other type of extant primate with which human beings share such close physical characteristics. From them we may learn much concerning the behavior of our earliest primate prototypes, because behavior, unlike bones, teeth, or tools, does not fossilize.
Several million years ago the chimpanzee and gorilla lines had already separated from one another, and the orangutan line even earlier than that. Throughout the eighteenth century there remained a considerable amount of confusion in distinguishing between orangutans, chimpanzees, and gorillas. The orangutan was the first to be recognized as a distinct genus -- only because of its remote habitat in Asia. It was not until 1847, on the basis of a single skull from Gabon, that the gorilla was confirmed as a separate genus from the chimpanzee." (Fossey, 1983)
Subspecies of Gorillas
Just as there are separate subspecies among orangutan and chimpanzee, there are separate suspecies of gorilla, also with morphological variations related probably primarily to habitat.
The gorillas, previously considered a single species, were recently divided into two species and five subspecies. The eastern gorilla (Gorilla beringei) includes the mountain gorilla (Gorilla beringei beringei) of the Virunga Volcanoes area of Rwanda, Uganda and the Democratic Republic of Congo, the yet unnamed, but distinct, population of Uganda's Bwindi (Impenetrable) Forest, and the eastern lowland gorilla (Gorilla beringei graueri). Western Africa is home to at least two additional taxa, the western lowland gorilla (Gorilla gorilla gorilla) and the Cross River gorilla (Gorilla gorilla diehli). The mountain, Bwindi and Cross River gorilla populations all number only in the hundreds and are considered critically endangered. (Once and Future Primate Order, Conservation International, 5 April 2000)
In western Africa there remain approximately 94,000 western lowland gorilla (Gorilla gorilla gorilla ) in the wild, but recent surveys indicate a decline of up to 56 percent across their range, due to poaching and disease. In areas hard hit by the Ebola virus, over 90 percent of great apes have been killed. It is this subspecies most frequently seen in captivity and mounted in museum collections.
Some 1000 miles to the east within the Virunga Volcanoes of Zaire, Uganda, and Rwanda live the last surviving mountain gorillas (Gorilla gorilla beringei ). The Virunga population were the subjects of Dian Fossey's field study. According to a recent census of mountain gorillas in the Virunga montane forests, led by the WWF-funded International Gorilla Conservation Program, about 380 mountain gorillas remain in the wild. This is a 17 percent increase in the population based on the count of 324 mountain gorillas more than a decade ago. The Bwindi gorilla population — previously classified as mountain gorillas by some scientists — numbers approximately 325 animals in the Bwindi Impenetrable National Park in Uganda. No mountain gorillas live in captivity.
Another recognized subspecies is known as Grauer's gorillas or the eastern lowland gorilla (Gorilla beringei graueri). An estimated population of 16,000 eastern lowland gorillas remain in the lowland and Albertine Rift montane forests of Democratic Republic of Congo, where they have been long-time victims of poaching in a historically war-torn area (WWF 2005). These figures are far higher than previously reported, both as a result of more sophisticated calculations on the basis of estimates of density, and of area of available habitat, and because of exciting new findings of gorillas in huge areas of west Africa where they were not previously suspected to be (Harcourt 1996). While the high numbers are good news, most live outside protected areas, and calculations of rate of forest disappearance in Africa indicate that numbers will crash in the next 150 years (Harcourt 1996).
A recent report from Conservation International states:
"The world population of the Endangered eastern lowland gorilla (Gorilla beringei graueri), found almost exclusively in eastern Democratic Republic of Congo (DRC), has plummeted by more than 70 percent in the past decade. Scientists estimate that fewer than 5,000 individuals remain, down sharply from 17,000 in 1994." (Conservation International, March 2004)
A subspecies of eastern gorilla, the eastern lowland gorilla now inhabits just 13 percent of its historic range. The eastern lowland gorilla is located approximately 600 miles from the nearest population of western lowland gorillas (WWF 2005). In 2005, there were only two female eastern lowland gorillas living in captivity at the Antwerp Zoo (ISIS Abstracts, February 2005).
The Cross River gorilla, which differs from the western lowland gorilla in skull and tooth dimensions, is restricted to the forested hills on the Nigerian-Cameroon border (WWF 2005). "The Cross River gorilla is a good example of why we must be very careful not to neglect possible diversity. In the nick of time we have realized these gorillas are distinct, just before it is finally too late to save them from oblivion," said Dr. John F. Oates, primatologist with Hunter College - CUNY, and co-author with Esteban Sarmiento of the American Museum of Natural History, of the re-description of the Cross River gorilla." (Primates on the Brink, Conservation International 10 January 2000). The Cross River gorilla population is estimated to be 200 animals, making it one of the rarest apes in the world.
There is one Cross River gorilla living in the Limbe Wildlife Centre (LWC) near Douala, in the West of Cameroon. The LWC takes in rescued animals, often orphans of the pet and bushmeat trades.
[Population estimates were updated in 2005, based on new information from Conservation International and the World Wildlife Fund
Distribution
The distribution of gorillas in Africa is discontinuous. The western lowland gorilla (Gorilla gorilla gorilla ) is found in south-east Nigeria, Cameroon, Equatorial Guinea, Gabon, Congo (Brazzaville), and the Central African Republic. A wide gap exists between this large area of distribution and the two other subspecies, each with extremely limited ranges; the mountain gorilla (Gorilla beringei beringei ) from the Virunga Volcanoes and the Bwindi Forest at altitudes of 2,100-3,650m (7-12,000 ft) on the Zaire-Rwanda border; and the eastern lowland gorilla (Gorilla beringei graueri ) from Zaire, to the west of Lake Tanganyika and Lake Edward, from the lower altitudes of 760-2255m (2500-7400 ft). See the distribution map (based on Harcourt 1996).