Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Individual study: Report from the Zaire Gorilla Conservation Project

Published source details

Aveling R. & Aveling C. (1987) Report from the Zaire Gorilla Conservation Project. Primate Conservation, 8, 162-164


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Run research project and ensure permanent human presence at site Primate Conservation

A before-and-after trial in 1984-1987 in tropical montane forests in the Virunga ecosystem found that mountain gorilla Gorilla beringei beringei populations that were regularly monitored by research staff since 1973 along with other interventions, increased from 242 to 279 individuals (15% increase) in 1981-1986. In addition, average group size increased by 17% (8.5 to 9.2 individuals) and the proportion of immatures increased by 8% (39.7 to 48.1) over the same period. In the same area, some groups were part of a gorilla viewing tourism program started in 1985. Anti-poaching guards regularly patrolled the area and removed snares. Guards were provided with better equipment, which allowed them to increase patrol frequency and effectiveness. An additional multi-organisational conservation project was initiated in 1979. The study does not distinguish between the effects of the different interventions mentioned above.

Run tourist projects and ensure permanent human presence at site Primate Conservation

A before-and-after trial in 1984-1987 in tropical montane forests in the Virunga ecosystem in Rwanda and the Democratic Republic of Congo found that mountain gorilla Gorilla beringei beringei populations involved in a tourism viewing project initiated in 1985 along with other interventions, increased from 242 to 279 individuals (15% increase) from 1981-1986. In addition, average group size increased by 17% (8.5 to 9.2 individuals) and the immature proportion increased by 8% (39.7 to 48.1) over the same time period. Regular total counts of this population were conducted since 1973 by research staff. Anti-poaching guards regularly patrolled the area and removed snares. Guards were  provided with better equipment, which allowed them to increase patrol frequency and effectiveness. An additional multi-organisation conservation project started in 1979. The study does not distinguish between the effects of the different interventions mentioned above.

Establish areas for conservation which are not protected by national or international legislation (e.g. private sector standards & codes) Primate Conservation

A before-and-after trial in 1984-1987 in tropical montane forest in the Virunga ecosystem in Rwanda and the Democratic Republic of Congo found that mountain gorillas Gorilla beringei beringei, protected by a conservation project funded by a consortium of organizations and initiated in 1979 along with other interventions, increased from 242 to 279 individuals (15% increase) from 1981 to 1986. Average group size increased by 17 % (8.5-9.2 individuals) and immature proportion increased by 8% (39.7-48.1) over the same time period. Regular total counts of this population were conducted since 1973. Anti-poaching guards regularly patrolled the area and removed snares. They were also provided with cars, a radio network, uniforms, more rations and other equipment, which allowed them to increase patrol frequency and effectiveness. In 1985, a gorilla viewing tourism program was started, during which three gorilla groups were habituated for tourist viewing. The study does not distinguish between the effects of the different interventions mentioned above.

Conduct regular anti-poaching patrols Primate Conservation

A before-and-after trial in 1984-1987 in tropical montane forest in the Virunga ecosystem in Rwanda and the Democratic Republic of Congo found that mountain gorillas Gorilla beringei beringei that were protected by regular anti-poaching patrols along with other interventions, increased from 242 to 279 (15% increase) individuals in 1981-1986. Average group size increased from 8.5 to 9.2 individuals (17% increase) and proportion immatures increased from 39.7 to 48.1 individuals (8% increase) over the same period. Regular total counts of this population were conducted since 1973 by research staff. Anti-poaching guards regularly removed snares. Guards were provided with cars, radio communication equipment, uniforms, more rations and other equipment, which allowed them to increase patrol frequency and effectiveness. In 1979, a multi-organisation funded conservation project was initiated. A gorilla viewing tourism programme started in 1985, during which three gorilla groups were habituated for tourist viewing. The study does not distinguish between the effects of the different interventions mentioned above.

(Summarised by JJ)

Provide better equipment (e.g. guns) to anti-poaching ranger patrols Primate Conservation

A before-and-after trial in 1984-1987 in tropical montane forest in the Virunga ecosystem in Rwanda and the Democratic Republic of Congo found that after anti-poaching guards were provided with better equipment that allowed them to increase patrol frequency and effectiveness, alongside other interventions, mountain gorilla Gorilla beringei beringei numbers increased from 242 to 279 individuals (15% increase) from 1981-1986. In addition, average group size increased from 8.5 to 9.2 individuals (17% increase) and immature proportion increased from 39.7 to 48.1% (8% increase) over the same time period. Regular total counts of this population were conducted since 1973 by research staff. Anti-poaching guards regularly removed ground snares and conducted anti-poaching patrols. In 1979, a multi-organisation funded conservation project was initiated. In 1985, a gorilla viewing tourism programme was started during which three gorilla groups were habituated for tourist viewing. The study does not distinguish between the effects of the different interventions mentioned above.

Regularly de-activate/remove ground snares Primate Conservation

A before-and-after trial in 1984-1987 in tropical montane forest in the Virunga ecosystem in Rwanda and the Democratic Republic of Congo found that mountain gorillas Gorilla beringei beringei ranging in habitat that was regularly patrolled for snares alongside other interventions, increased from 242 to 279 individuals (15% increase) in 1981-1986. Average group size increased from 8.5 to 9.2 individuals (17% increase) and immature proportion increased from 39.7 to 48.1% (8% increase) over the same time period. Regular total counts of this population were conducted since 1973. Anti-poaching guards regularly patrolled the area. Guards were provided with cars, radio communication, uniforms, more rations and other equipment that allowed them to increase patrol frequency and effectiveness. In 1985, a gorilla viewing tourism programme was started during which three gorilla groups were habituated for tourist viewing. The study does not distinguish between the effects of the different interventions mentioned above.

(Summarised by JJ)

Run tourist projects and ensure permanent human presence at site Primate Conservation

A controlled study in 1984-1987 in tropical montane forest in Virunga National Park in the Democratic Republic of Congo found that the resident mountain gorilla Gorilla beringei beringei population that was regularly visited by tourists had increased over three years. The percentage of immature gorillas in the groups regularly monitored by the tourism project was 50.8%, compared to 40.8% in groups that were not monitored. However, no statistical tests were carried out to determine whether this difference was significant. Furthermore, average group size in the monitored vs unmonitored population was 10.4 and 7.1 gorillas, respectively. Within a period of ten months, tourist receipts rose from zero to about US$1800/ month. Three gorilla groups living at the edge of the park were habituated to human presence and one of them received once-a-day visits from a maximum of six people since September 1985.

Implement local no-hunting community policies/traditional hunting ban Primate Conservation

A controlled study in 1984-1987 in tropical lowland forest in the Masisi Highlands in Democratic Republic of Congo found that a small eastern lowland gorilla Gorilla beringei graueri population had increased after the implementation of a local gorilla hunting ban. The population increased and by 1987 there were 70 gorillas living in a 30 km2 area inhabited by between 5,000-10,000 people. However, population size before the ban was not reported and no statistical tests were carried out to determine whether this difference was significant. The owner of a cattle ranch had implemented the ban and encouraged the local people to do adhere to it. Gorillas nested as close as 30 m from houses and regularly crossed fields of beans or maize without feeding on them. In addition, they were observed in pastures among cattle and seen to eat the bark of Eucalypt trees. They become partially habituated to humans and as a consequence, could easily be observed.