Population dynamics of the virunga gorillas: 1959–1978

Abstract

The Virunga gorilla population declined from 400–500 individuals in 1959–1960 to 260–290 in 1971–1973. Most of this decline is attributed to heavy hunting pressure in the Zairian sector. Large-scale habitat destruction and cattle disturbance in the Rwandan and Ugandan sectors are held responsible for further gorilla losses. Changes are documented in group size and composition, as well as in total numbers. Between 1971–1973 and 1976–1978, the population stabilised in the range of 252–285 gorillas. A tendency toward larger group sizes was observed in certain sectors, and the overall percentage of infants increased. Comparison of the 1976–1978 group compositions with a simulated stable age structure model indicates a more healthy population than in 1971–1973. Potential for population growth is shown to be greater than previously predicted. Failure to increase in the inter-census period is attributed to continued poaching pressure. Current conservation efforts are described.