HirwaOur Mountain and Grauer's Gorilla Patients

Gorillas only exist in the wild in Africa, where four different gorilla subspecies can be found. There are two subspecies of Western Gorillas including western lowland gorillas (Gorilla gorilla gorilla) and Cross River gorillas (Gorilla gorilla diehli), and two subspecies of Eastern Gorillas including mountain gorillas (Gorilla beringei beringei) and eastern lowland gorillas (Gorilla beringei graueri). 

Gorilla Doctors is dedicated to the care of mountain gorillas, which stand out from their close cousins by their thick fur and ability to survive at high altitude. Mountain gorillas live in central Africa, with about 480 animals living in the Virunga Volcanoes Massif, which combines Volcanoes National Park in Rwanda, Virunga National Park in DRC, and Mgahinga National Park in Uganda. The remaining 400 or so individuals live within the boundaries of Bwindi Impenetrable National Park in Uganda. The Gorilla Doctors also monitor the health of eastern lowland or Grauer's gorillas that live in Kahuzi-Biega National Park and the Mt. Tshiabirimu area of Virunga National Park, DRC. The population of this subspecies is difficult to estimate due to the instability of the region in which they live, but there may be several thousand individuals, down from tens of thousands as recently as the mid-1990s. 

The Gorilla Doctors veterinary team monitors and treats gorillas that are human habituated—family groups that have grown accustomed to the presence of humans. About 73% of mountain gorillas in the Virunga Massif are habituated for tourism or research purposes, while only about 50% of mountain gorillas in Bwindi Impenetrable National Park are habituated. There are fewer than 100 habituated eastern lowland gorillas, all living in Kahuzi-Biega National Park in eastern DRC. 

Both mountain and eastern lowland gorillas live in groups ranging in size from a handful of individuals to several dozen members. A dominant silverback—an adult male who shows his sexual maturity by the silver fur on his back—leads each group, which may include several subordinate silverbacks, blackbacks (adult males who have not yet reached sexual maturity), adult females, juveniles (ranging from age 4 to 8), and infants (age 3 or younger).