Pan troglodytes Blumenbach, 1799
POPULATION
All three subspecies are listed in the 1996 IUCN Red List of Threatened Animals as endangered, but the western form (verus) is the most threatened. DNA analysis indicates that western chimpanzees may have been isolated from subspecies for as long as 1.5 million years; some taxonomists believe that they should be classified as an entirely distinct species.
Current estimates of chimpanzee numbers by the IUCN Species Survival Commission's African Primate Specialist Group*, put the numbers at:
Western chimpanzees: 12,000; patchily distributed between Nigeria (or Togo) and Senegal. Population estimates are crude according to IUCN.
Central chimpanzees: 80,000; found chiefly in Gabon, Cameroon, and Congo, where substantial areas of forest remain.
Eastern chimpanzees: 13,000; between Tanzania and Zaïre (north and east of the Zaïre River). Approximately 8,000 are estimated to occur outside Zaïre with 5,000 in Uganda, but surveys are needed. The tiny chimpanzee populations in Rwanda and Burundi are the most severely threatened.
"Guestimates" of chimpanzee numbers are highly variable, based on the extent of their habitat. Some scientists believe there may be as many as 200,000 in Africa, but this figure includes a hypothetical population in the rainforests of northern and eastern Zaïre which nobody has yet surveyed. If these are eventually found to harbour few chimpanzees, the true figure for Africa may be nearer to 100,000, close to the estimate given by IUCN's African Primate Specialist Group. 21
Chimpanzees are now extinct in three of the 25 countries they once inhabited (Gambia, Burkina Faso, and Benin) and possibly Togo. Numbers in five countries (Ghana, Guinea-Bissau, Nigeria, Burundi and Rwanda) are so depleted that extinction is expected soon, and another five (Senegal, Mali, the Cabinda enclave of Angola, Equatorial Guinea and Sudan) contain such small, dispersed remnants that the populations are severely at risk.6,19
Major population: The largest remaining populations occur in central Africa, mainly Gabon, Zaïre and Cameroon, although a recent survey suggests that Côte d'Ivoire also contains substantial numbers.4,10
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