Small populations are particularly susceptible or 1.3% annual growth rate since 1972. This is lower than growth estimates made in several population viability to disturbance. Routine censusing to monitor changes is important for understanding both population dynamics analyses, but approximately 5% of the 1989 population is known to have died due to military activity over the and the eCectiveness of conservation strategies. Mountain gorillas Gorilla beringei beringei in the Virunga Volcanoes last decade. DiCerent subsets of the population exhibited diCerent responses to disturbance caused by war. We region of Rwanda, Uganda and the Democratic Republic of Congo have been censused five times since 1970. discuss conservation strategies that are likely to have contributed to an increase in the gorilla population during However, due to war and political unrest in the region since 1990, no census had been conducted since 1989, this time of turmoil. While the population has grown, the results should be viewed with caution, not only because when the population was thought to number 324 gorillas. In 2000 we estimated population size using repeated all known growth during the last decade can be attributed to one subset of the population, but also because the region observations of 17 habituated groups and information on 15 unhabituated groups obtained during patrols. The is still plagued by political unrest. minimum population was 359 gorillas, and a best-case scenario correcting for groups that might not have been Keywords Democratic Republic of Congo, Gorilla beringei beringei, war, population size, Rwanda, Uganda, counted was 395. Using the minimum population and best-case scenario respectively, this represents a 0.9% or Virunga Volcanoes. 1.8% annual growth rate over the last decade and 1.0% could have a critical impact on the ability of such

Abstract. Effective management of protected areas is dependent on information on the illegal and legal use of the habitat by people, the ecological and behavioural needs of key species, and trends in resource availability and ecological processes. The International Gorilla Conservation Programme working with the protected area authorities in Rwanda, Uganda and the Democratic Republic of Congo has developed a ranger based monitoring system, using basic protocols for data collection that guide protected area staff in park management. This programme is a key management tool for the three park authorities responsible for the conservation of the mountain gorilla (Gorilla beringei beringei) in the Virunga and Bwindi forest blocks. The programme was initiated in 1997 and has enabled the gathering of extensive information on illegal activities, key species of fauna and flora, and habituated and unhabituated groups of gorillas. Ranger based monitoring is a simple and cost effective tool that can be sustained in the parks in the Virunga-Bwindi region with limited external support. It provides park managers with information that prompts appropriate responses to threats to the ecosystem. For example information on the distribution of illegal activities determines targeted patrol coverage to address specific threats. The bottom-up approach of ranger based monitoring includes a strong capacity building component and empowers field staff in park management activities.

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