This led to a massive reduction in mountain gorilla population numbers by the mid-1970s. The rest of the worldwide mountain gorilla population is in the nearby Virunga Mountains. The mountain gorilla also has the thickest hair. The mountain gorilla is primarily terrestrial and quadrupedal. The slopes of Mt. Sabyinyo are a habitat for the critically endangered mountain gorilla. The main source of revenue, however, is tourism, mainly mountain gorilla visitation. He now lives at the park headquarters in Rumangabo, bordering the park's mountain gorilla sector. An exception to this declining trend is the mountain gorilla. Despite their recent population growth, the mountain gorilla remains threatened. The park is best known for the mountain gorilla ("Gorilla beringei beringei"). Outside the native range, the mountain gorilla is not held in captivity at all. The mountain gorilla ("G. b. beringei") has only about 1,000 individuals.