African Gorilla Population & Trends

Mountain Gorilla Population estimates and trends in Africa

Population counts and estimates of mountain gorillas are commonly carried out on the basis of nest or sleeping site counts (e.g. Inogwabini et al., 2000). Adults and immature weaned animals build new nests to sleep in each night. The nests are counted and any dung adjacent to each nest examined gives a reliable indication of group size as well as age of animal, particularly when the counts are repeated over several nights.

Mountain Gorilla in its Natural Environment

The number of mountain gorillas declined throughout the 1970s and early 1980s, and some declines were seen into the 1990s (e.g Binyeri et al., 2002). This could not allow gorilla trekking safaris in Africa. IUCN (1982) described a decline in the mountain gorilla numbers in the Virungas, from 400-500 in the late 1950s, to 275 in 1973 to 250 by 1981, with most of thedecline occurring in the DRC section. However, by the mid 1980s the mountain gorillas of the Virungas hadstarted to very gradually increase again. The 1989 count of mountain gorillas in the Volcans National Park, Virunga National Park and Mgahinga National Park was about 306 animals (Plumptre and Harris, 1995). Most recently a population estimate, based on repeated observations of 17 habituated groups and information on 15 unhabituated groups, has shown the population of the Virunga mountain gorilla to be between 359 and 395 (Kalpers et al., 2003).

1979 estimates showed there to be 95-130 mountain gorillas in the Bwindi Impenetrable Forest Reserve (IUCN, 1982). Harcourt et al. (1981) noted a total population size of c.155 in Bwindi (where 33% of the population was counted). More recently McNeilage et al. (2001) estimated the population in Bwindi- Impenetrable National Park in 1997 to be 292 individuals and note that this population appeared to be stable.
At least 300 individuals were reported in Bwindi Impenetrable Forest National Park (Uganda Wildlife Division, 2002a).

The mountain gorilla appears to be gradually increasing in numbers and this has favored rapid growth of Gorilla Safaris Uganda. Based on recent estimates (Kalpers et al., 2003 and McNeilage et al., 2001), the total number of mountain gorillas may be between 651 and 687, or according to Plumptre et al. (2003) there are a total of approximately 650-700 mountain gorillas. According to WWF (2002) the Virunga population of mountain gorilla has increased by 14% in the last 12 years. The Bwindi gorilla trekking and gorilla population is stable and may also be increasing (Uganda Wildlife Division, 2002a; WWF, 2002; McNeilage et al., 2001).