15 - Status of the Virunga mountain gorilla population

Summary

Introduction

The mountain gorilla subspecies is considered to include two geographically isolated populations in east-central Africa (Garner & Ryder, 1996). One population inhabits the Bwindi Impenetrable Forest National Park of southwestern Uganda and comprises about 300 individuals (McNeilage et al., 1998), while the other, similarly sized, population is restricted to the Virunga Volcanoes area (Figure 15.1). This chapter examines the conservation status of the Virunga mountain gorilla population and its vulnerability to extinction factors.

The Virunga gorillas are limited to three national parks bordering three nations: Parc National des Virunga, Parc National des Volcans, and Mgahinga Gorilla National Park. Together, they comprise an approximate 430km_ protected habitat that is commonly referred to as the “Virunga Conservation Area”. The long history of research in the region (see Introduction to this volume) has provided several decades worth of behavioral, ecological, and demographic data on this population, including the results of several censuses. The dramatic decline of the Virunga population in the 1970s (Harcourt & Fossey, 1981) raised the distinct possibility that this population was at risk of becoming extinct in the same century in which it had been discovered (Fossey, 1983). This concern has provided a strong rationale for subsequent population status assessments. The question of what is a viable population, or minimum viable population, has been answered in different ways and is an area of continuing debate (e.g. Woodruff, 1989). There is broad agreement, however, on the importance of population attributes (e.g. size and structure) and environmental factors (e.g. disease, habitat loss) that affect viability, and such variables are often included in population viability (or vulnerability) analyses (PVA).