Western Lowland Gorilla

Gorilla gorilla gorilla

About the Western Lowland Gorilla


Geographic Range:


Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Gorilla
Species: gorilla
Subspecies: gorilla

Gorillas are the world’s largest living primates. Male western lowland gorillas can grow to 5.5-feet tall and weigh up to 450 pounds. Females can grow to 4.5-feet tall and weigh up to 250 pounds. Western lowland gorillas live in groups, or “bands” in or near African forests. The alpha male leads the band and those who challenge him are apt to be cowed by impressive shows of physical power—he may throw things, make aggressive charges, pound his huge chest while barking out powerful hoots, or unleash a frightening roar.

Gorilla Facts

The western lowland gorilla has dark brown to black fur and black skin. Facial features include a prominent brow ridge, small eyes and ears, large nostrils and short muzzles. Gorillas have broad, strong teeth and large jaw muscles. Coarse black to brown hair covers the body except for the face, hands and feet. The hair of mature males from shoulders to rump grows gray with age giving them the nickname "silverback." Males have an enlarged sagittal crest, which is a bone ridge on the top of the cranium.

Height: Males up to 5.5 feet tall; females up to 4.5 feet
Weight: Males up to 450 pounds; females up to 250 pounds

Gorillas eat more than 200 types of plants including fruits, flowers, shoots, bulbs, bark and leaves, as well as invertebrates (like ants and termites).

Gorillas don't have a breeding season. The female's estrus cycle occurs every 30-33 days. Usually only the dominant silverback male gets to breed, but sometimes a troupe is led by multiple younger males (called “black backs” due to the lack of silver coloration on their back).

Lasting 250 to 285 days, gestation usually results in one offspring (twins are rare). Young are weaned after 36 to 48 months. Males reach sexual maturity in 6-11 years and females in 6-8 years. When mature, both genders leave their group to find another to prevent inbreeding.

Western lowland gorilla groups generally consist of one dominant silverback male and multiple females and their offspring. At times gorilla groups may consist of multiple males with more than one silverback or multiple younger males. Their group size in the wild generally averages eight individuals, but groups as large as 20 have been recorded. The silverback male responds to challenges made against him by an intimidating display. He may make aggressive charges, stand upright and pound his huge chest while barking out powerful hoots or even throw things.

Due to their dependence on seasonal fruit, western lowland gorillas have the largest home range of the four gorilla subspecies. They spend most of their time on the ground, although the young may spend some time in the lower canopy while foraging. Gorillas build nests for both day and night. Night nests consist of branches and leaves; day nests provide a cushion on the ground.

Tropical forests, swamp forests, clearings and forest edges in the African countries of Cameroon, Gabon, Central African Republic, Republic of Congo, Equatorial Guinea, Cabinda (Angola), and possibly Democratic Republic of Congo although it is likely they are extinct there.

Median Life Expectancy:
Males: 31.7 years

Females: 38.3 years

Threats in the wild:
Gorilla numbers in the wild are declining at a rapid rate. Ebola virus (hemorrhagic fever) and the commercial bush meat trade, along with habitat loss and poaching are the main causes behind gorilla deaths. The loss of their forest habitat is a twofold threat since habitat loss also brings hungry people who hunt gorillas for bushmeat.

Committed to Conservation

Gorilla numbers in the wild are declining at a rapid rate. Ebola virus and the commercial bush meat trade, along with extreme habitat loss and poaching are the main causes behind gorilla deaths. As a result, the western lowland gorilla’s numbers have declined by more than 60% over the last 20 to 25 years. According to the World Wildlife Federation, even if all of the threats to this species were removed, scientists calculate that the population would require some 75 years to recover.


Between 2010 and 2014, 52 AZA-accredited zoos and aquariums reported taking part in a variety of field conservation projects benefiting gorillas. Over those five years alone, the AZA community invested $4.5 million in gorilla conservation. In 2010, the Ape TAG Conservation Initiative was launched by AZA's Ape Taxon Advisory Group (TAG), with the goal of increasing zoo support for ape conservation. Through the initiative, AZA institutions continually contribute resources to global ape conservation. Learn more about AZA SAFE.

Species Survival Plan

Zoo New England participates in the Western lowland gorilla Species Survival Plan. By sharing research and knowledge, participating institutions work together to establish guidelines that best ensure the health of captive populations, and with success, the survival of otherwise extinct species.