Gorillas are the largest members of the primate family and are closely related to humans, with 98% of their DNA identical to that of humans. Unlike other primates they are terrestrial, meaning they do not climb trees and are land dwelling, inhabiting the tropical rainforests of central Africa. Historically the gorilla has been portrayed as a vicious killer; however they are shy gentle creatures that would not attack humans unless provoked.
Gorillas are classified as mammals, which is defined by the Oxford English dictionary as a ‘Warm-blooded vertebrate animal that has hair or fur, secretes milk, and (typically) bears live young’ (0ED 2010). Upon their discovery gorillas were classified as one species, however they are now separated into two species and four sub species according to geographical location and physical characteristics. They live in groups called a troop lead by a dominant silverback male, and are highly sociable animals, maintaining strong bonds between group members.
In the wild their only predators are leopards, which can attack vulnerable youngsters and the biggest threat to gorillas is man. In recent decades gorilla populations have been affected by habitat loss, disease and poaching. Subsequently all gorilla species are classified as endangered by the International Union for Conservation of Nature (IUCN). Due to the vast dense areas in which they live it is difficult to monitor and protect gorilla populations and therefore difficult to implement successful conservation techniques. However conservation efforts persist and several governmental and non-governmental organizations named 2009 the ‘Year of the Gorilla’ with the aim of working together to further improve gorilla conservation.
Western lowland gorilla (Gorilla gorilla)
There are four subspecies of gorillas: the eastern lowland or Grauer’s gorilla (Gorilla beringei graueri); the mountain gorilla (Gorilla beringei beringei); the western lowland gorilla (Gorilla gorilla gorilla); and the Cross River gorilla (Gorilla gorilla diehl).
Like all great apes, gorillas have arms that are longer than their legs and tend to walk on all four limbs at certain times – a movement that is called knuckle walking. Adult males are known as ‘silverbacks’ due to the distinctive silver-colored hair on their backs.
Gorillas’ appearances can vary based on sub-species, but for the most part, the western subspecies tend to be brownish gray in color, while the eastern and mountain gorillas tend to have a more blackish coat. Mountain gorillas also have longer and thicker fur which is adapted to their colder mountainous habitat. The three lowland subspecies of gorillas sport short, fine hair. Eastern lowland gorillas are the largest of the four subspecies.
Gorillas are herbivores and eat leaves, shoots, roots, vines and fruits.
Eastern lowland gorilla numbers have rapidly declined to below 5,000 today. Critically endangered, there are fewer than 300 Cross River gorillas. Mountain gorillas, another endangered subspecies, number at around 700. A recent survey has shown that there are around 150,000-200,000 western lowland gorillas.
Eastern lowland gorillas are found in part of the eastern Democratic Republic of Congo (DRC), Uganda and Rwanda, while mountain gorillas are only found within the Virunga mountain region straddling the DRC, Rwanda and Uganda borders, as well as the Bwindi Impenetrable National Park in Uganda. Western lowland gorillas inhabit Cameroon, Nigeria, the Central African Republic, the Republic of Congo, eastern DRC, Equatorial Guinea, Gabon and Angola. Cross River gorillas are confined to a small region in Nigeria and Cameroon.
Gorillas are ground-dwelling and live in groups of 6-12 with the oldest and largest silverback leading a family of females, their young and younger males called blackbacks. The silverback makes the decisions on when his group wakes up, eats, moves and rests for the night. Because he must protect his family at all times, the silverback tends to be the most aggressive. In such situations, he will beat his chest and charge at the perceived threat.
Gorillas are shy animals that are most active during the day. At dusk, each gorilla constructs a ‘nest’ of leaves and plant material in which it will sleep. Mothers usually share their nests with nursing infants.
Young males may leave their family groups as they become older and either live as solitary silverbacks or create their own family groups. The silverback has the exclusive rights to mate with the females in his group.
Reproduction Mating Season: Throughout the year. Gestation: 8.5 months. Litter size: 1 baby. Gorilla infants are helpless at birth and weigh about 3-4 lbs. They learn to crawl at about 2 months and are walking by the time they are around 8 or 9 months. Mother gorillas nurse their babies for about 3 years, following which the young become more independent.
As indicated above, Gorillas are threatened by habitat loss due to increasing human populations, poaching for the bush meat trade and diseases like ebola. Species that live in higher elevations, like mountain gorillas, are also affected by climate change, which has the potential to impact gorillas directly by altering their habitat, and indirectly by affecting agriculture yields in nearby communities, which in turn puts more pressure on remaining habitat.
Gorilla distribution map world wide.