Gorilla distribution has been reduced in many countries through hunting and destruction of suitable habitat. Forest clearance for agriculture and commercial logging and hunting for food are factors which adversely affect Gorillas and are likely to increase as human pressure increases. African lowland and montane forests are rapidly being destroyed to make way for food production uses such as cropping and livestock grazing. In Central Africa, commercial logging and petroleum exploitation are becoming an increasingly significant threat to the habitat of the gorilla. A number of Gorillas, especially infants, are captured annually for sale abroad. Gorillas are frequently maimed or killed throughout their range by traps and snares intended for other animals, particularly game species such as bushbuck and black-fronted Duiker. A potential threat to gorillas is exposure to human diseases. This particularly affects groups of habituated gorillas which come in close contact with humans in areas where gorilla tourism is promoted.
Conflict in the Congo border areas with Uganda and Rwanda is increasing the threat to gorillas as national park guards as disarmed and refugees are creating pressure on the resources of protected areas. Revenue from tourism that sustains the parks is being lost due to the conflicts.
Favoured Gorilla habitats are forest edges, regenerating (secondary) forest, montane forest, riverine forest and in primary forest at low density. Gorillas occur in two regions of Africa, equatorial west Africa and east central Africa, the two areas are separated by the 1,000km of the Congo Basin tropical forest. Three subspecies are recognised: [G. g. gorilla] Western Lowland Gorilla; [G. g. graueri] Eastern Lowland Gorilla; and [G. g. berengei] Mountain Gorilla. However investigations during 1994 into the genetic structure of the three Gorilla subspecies, suggests that two separate species and not three separate subspecies may exist. If correct, it would mean that true Mountain Gorillas occur only in the Virunga Range.
Gorillas are listed (1997) on "Appendix I" of CITES restricting all international trade. All three subspecies of gorilla are categorised in the 1996 IUCN Red List of Threatened Animals as "Endangered" to "Critically Endangered".
A 1996 estimate gives a total of about 126,000 animals. Gorillas ranged into the northern Congo basin early this century, north of the Uele River, but are now believed to be extinct in this region. A survey in 1987 by the Nigerian Conservation Foundation, estimated 300 Gorillas inhabited Cross River State in south-east Nigeria. It has been estimated that at least 20 gorillas per annum are killed in Cameroon for food, while, at most, one enters trade. In early 1995 a juvenile male gorilla was seized by Philippine customs. In March 1995, four Mountain Gorillas were killed by poachers in Bwindi-Impenetrable National Park, probably in order to capture one or more infants, and three silverback males and a female were killed in the Parc National Des Virungas.