Crash course on Mountain Gorillas

Know the difference between ‘wild’, ‘habituated’, ‘non-habituated’, and ‘captive’ mountain gorillas? Read through these mountain gorilla facts and figures to make yourself a mountain gorilla expert.

  • Scientific name: Gorilla beringei beringei
  • Found in: Democratic Republic of Congo, Rwanda, and Uganda
  • Status: Critically endangered
  • Life span: 35-40 years

There are two populations of mountain gorillas:

  1. Virunga Massif, which includes Mikeno Sector of the Virunga National Park in DRC, Volcanoes National Park in Rwanda, and Mgahinga Gorilla National Park in Uganda (This population is estimated at 480 individuals as per the last complete census in 2010.)
  2. Virunga Massif population of mountain gorillas over the years, based on censuses of the population. Census methods are evolving and now include genetic analysis to estimate the most accurate population numbers.

    Virunga Massif population of mountain gorillas over the years, based on censuses of the population. Census methods are evolving and now include genetic analysis to estimate the most accurate population numbers.

  3. Bwindi Impenetrable National Park (This population is estimated at 400 individuals as per the last complete census in 2011.)
The Bwindi population of mountain gorillas have been censused four times since 1997. This graph was updated on November 13, 2012, with the release of the 2011 census numbers for Bwindi.

The Bwindi population of mountain gorillas have been censused four times since 1997. This graph was updated on November 13, 2012, with the release of the 2011 census numbers for Bwindi.

Total world population estimated at around 880 mountain gorillas (Updated Nov 13, 2012).

All of these mountain gorillas are wild, ranging in their own habitat. However, some are habituated to the presence of people for either research or tourism, and some are non-habituated and therefore do not have regular or any contact with people.

Habituation is a process in which a group of gorillas slowly accept and become comfortable with the presence of people within viewing distance of the group. The process of habituation usually takes from two to three years for mountain gorillas.

There are no zoos which have captive mountain gorillas.

There are, as of October 1, 2012, three captive mountain gorillas being cared for at the Senkwekwe Center in Rumangabo, Democratic Republic of Congo.

Data is collected on the habituated mountain gorillas on a daily basis, and if a life-threatening injury or illness is observed, specialized veterinarians are called in to treat the mountain gorillas in situ, or within the park

A complete census can count all the mountain gorillas in a population – both habituated and non-habituated – because the census methods involve the counting and measurements of mountain gorilla night nest and dung. Genetic information extracted from dung samples collected during the census give each individual a unique genetic fingerprint to make sure the same gorilla is not counted twice during the field data collection.

Each individual mountain gorilla makes a fresh nest of vegetation each night, with infants less than three or four years sleeping with their mothers.

Mountain gorillas live in family groups, led by a dominant silverback. Some silverbacks will roam without a group and are referred to as lone silverbacks.

Age Categories for Females:

  • Infant – from birth to 3 1/2 years, when the gorilla is weaned from its mother’s milk
  • Juvenile – from 3 1/2 years to 6 years, a gorilla that is weaned but not yet reproductively mature
  • Sub-adult – from 6 years to 8 years
  • Adult female – from 8 years until death, a reproducing female

Age Categories for Males:

  • Infant – from birth to 3 1/2 years, when the gorilla is weaned from its mother’s milk
  • Juvenile – from 3 1/2 to 6 years, a gorilla that is weaned but not yet reproductively mature
  • Sub-adult – from 6 years to 8 years
  • Blackback – from 8 years until 12 years, an adult male
  • Silverback – from 12 years until death, a mature male gorilla develops silver hair on his back

There are four subspecies of gorillas found in Africa (and gorillas are only found in Africa):

  1. Western lowland gorilla (Gorilla gorilla gorilla)
  2. Cross river gorilla (Gorilla gorilla diehli)
  3. Eastern lowland gorilla or Grauer’s Gorilla (Gorilla beringei graueri)
  4. Mountain gorilla (Gorilla beringei beringei)

NOTE: This post was updated on November 13, 2012, with the results of the 2011 census of mountain gorillas in Bwindi.

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