Western Gorilla is one of the two species of genus Gorilla, and so far the most populous. This specie is sub-divided into the western lowland gorilla (scientifically known as Gorilla gorilla gorilla) with more than 100,000 individuals as well as Cross River Gorilla (scientifically known as Gorilla gorilla diehli) with about 250 to 300 individuals.
Physical description
These gorillas are more lightly colored than Eastern gorillas with their fur being black, dark grey or dark brown-grey in addition to having brownish foreheads. An average male western gorilla has a standing height of between 1.67 and 1.76 meters tall, and weighs averagely 146 kilograms. Females weigh between 58 and 72 kilograms and this applies to the ones in the wild while gorillas in captivity can weigh averagely 157 kilograms for males and 80 kilograms for females.
Western gorillas rarely live as sole or independent individuals but instead in groups of varying sizes between 2 and 20 members. Additionally, these groups are made up of one dominant silverback, subordinate silverbacks, several females and their young ones. The dominant silverback is the ultimate decision maker and in-charge of providing security to the group and black backs (younger males) normally leave the group on reaching maturity while females move to other groups prior to breeding (8-9 years).
The diet of western gorillas is typically high in fiber hence consume banana pith, stems, barks, leaves, flowers, fruits, invertebrates and sometimes soil. The number of times these plant materials/parts are consumed largely depends on season and a particular gorilla group.
Western lowland gorillas
Also known as Gorilla gorilla gorilla, the western lowland gorillas are the smallest yet the most populous of the four gorilla sub-species that also comprise of mountain gorillas, Cross River Gorillas and Eastern lowland gorillas. Just like their counterparts (Cross River Gorillas), the western lowland gorillas are endangered and threatened by habitat loss.
These extraordinarily popular gorilla species are characterized by short black-brown hair, more protruding ridge along their brows and longer arms. Additionally, their infants have a cluster of white hair on their backsides while grown-ups develop strips of silver in their hair
Habitat and range
Western lowland Gorillas live in the countries of Central and West Africa especially Equatorial Guinea, Angola, Gabon, Democratic Republic of Congo, Cameroon, Republic of Congo (Congo Brazzaville) and Central African Republic. They mainly occupy the dense Tropical rainforests where they enjoy abundant food for their special vegetarian diet. They subsist on fruits, roots, tree barks, shoots, pulp, wild celery and many other plant parts in their natural environment.
They are terrestrial and live in groups/troops of up to 30 members, led by a dominant silverback (named silverback owing to the saddle of silver hair that replaces their otherwise dark fur on their backs), subordinate males, several young males (black backs), adult females and their young ones. The dominant silverback takes care of group activities like foraging, nesting, movement and many others.
Western lowland gorillas are generally quiet and calm creatures with several means of vocalizations in form of barking, hooting, screaming and all these demonstrate different meaning. These gorillas are the most popular sub-species in captivity.
Cross River Gorillas
Scientifically referred as Gorilla gorilla diehli, the Cross River Gorillas are the rarest and least-mentioned of the four gorilla sub-species. These are found within the forested hills and mountains of only two countries-Nigeria and Cameroon border with only about 250 to 300 individuals in the wild living at the headwaters of Cross River in Nigeria. They are confined to the Boshi Extension, Mbe Mountains, Okwanggo of Nigeria’s Cross River State and Afi River Forest Reserves, Mbulu Forest, Takamanda and Mone River Forest Reserves as well as Cameroon’s South-west Province.
The Cross River Gorillas are separated from the closest population of their close relatives (western lowland gorillas) of Nigeria by approximately 300 kilometers as well as by 250 kilometers from the ones in Ebo Forest of Cameroon. With an estimated population of only 250 individuals (2014 statistics), they are so far the rarest Great Apes in the World.
When compared to the western lowland gorillas, the beautiful Cross River Gorillas have remarkably smaller palates (roof of the mouth), shorter skulls and smaller cranial vaults although they are slightly larger than their counterparts.
As far as habitat is concerned, these gorillas prefer occupying the thick forest that is greatly unoccupied by human population and given their small body size, they need vast and diverse areas of the forest to meet up their changing habitat requirements. Unlike their counterparts that live in large groups, Cross River Gorillas live in smaller groups of 4-7 individuals with few males and females.
Besides being categorized as critically endangered under IUCN Red List, the Cross River Gorillas are also understudied, because of their habitat terrain and scattered population hence creating significant geographical restrictions. In the past they were known to live in lowland areas but given the high rate of habitat loss, they were forced to move to highland areas.
