Population Growth
Gorillas give birth to usually just one child at a time, and spend many months caring for it. As a result, birth rate is very low. The infant mortality rate is very high, but in adults, is only five percent. Gorillas are very large animals and so they require a lot of food. As a result, they would be limited in number by the amount of food available to them and how far they had to travel to obtain the food. However, they are an endangered species and their numbers are low, so food is not a problem. Their population is slowly increasing due to increased protection of habitat. Illegal deforestation of forests in Virunga National Park will cut into their habitat, and may send their population plummeting.
Source: http://wwf.panda.org/what_we_do/endangered_species/great_apes/gorillas/
http://wwf.panda.org/what_we_do/endangered_species/great_apes/gorillas/mountain_gorilla
http://wwf.panda.org/what_we_do/endangered_species/great_apes/gorillas/mountain_gorilla