Western Lowland  GORILLA

Gorilla gorilla beringei

STATUS: 

Critically endangered on the World Conservation Union's (IUCN's) Red List of Threatened Animals

DESCRIPTION: 

Lowland gorilla hair is short, soft, and very fine. There is no under fur (a thick layer of insulating hair close to the skin, such as on dogs or minks). Lowland gorillas’ coats are suited for warm, moist forest habitats. Western lowland gorillas have a more pronounced brow ridge, and ears that appear small in relation to their heads. They also have a different shaped nose and lip. Adult male gorillas’ heads look conical due to the large bony crests on the top (sagittal) and back (nuchal) of the skull. These crests anchor the massive muscles used to support and operate their large jaws and teeth. Adult female gorillas also have these crests, but they are much less pronounced. In comparison to the mountain gorilla, the western lowland gorilla has a wider and larger skull and the big toe of the western lowland gorilla is spread apart more from the alignment of his other four toes. Males develop a streak of silver hair on their backs when they mature and are called "silverbacks."

POPULATION: 

Of the four subspecies, the western lowland gorilla is the most numerous and widespread, with a population of approximately 94,000, but recent surveys indicate a decline of up to 56 percent across their range, due to poaching and disease.

LIFESPAN: 

Gorillas may live about 35 years in the wild, and up to 54 in zoos.

RANGE: 

Western lowland gorillas live in lowland tropical forests in Cameroon, the Central African Republic, the Republic of Congo, Equatorial Guinea, Gabon, and Nigeria.

HABITAT: 

Gorillas live in moist tropical forests, often in secondary, or re-growing, forests or along forest edges, where clearings provide an abundance of low, edible vegetation.

FOOD: 

Gorillas are primarily herbivorous, eating the leaves and stems of herbs, shrubs, and vines. In some areas, they raid farms, eating and trampling crops. They also will eat rotten wood and small animals. The diet of western lowland gorillas also includes the fleshy fruits of close to a hundred seasonally fruiting tree species; the diets of other gorilla subspecies include proportionally less fruit.

BEHAVIOR: 

Gorillas live in groups. Each group usually contains one or more silverbacks and two to ten females and young. Newly established silverbacks may kill young not sired by them, but otherwise, gorilla family life is mostly peaceful.  Gorillas spend their mornings and evenings feeding, usually covering only a small area of forest at a time. Groups spend the middle of the day sleeping, playing, or grooming (females groom their young or a silverback). At night, gorillas fashion nests of leaves and branches on which to sleep; unweaned infants sleep in their mothers' nests. The western lowland gorilla is characterized as a quiet, peaceful, and non-aggressive animal. They never attack unless provoked. However, males do fight over acquisition and defense of females, and the new leader of a group may kill unrelated infants. This causes the females to begin cycling sooner. An adult male protecting his group may attempt to intimidate his aggressor by standing on his legs and slapping its chest with cupped or flat hands while roaring and screaming. If this elaborate display is unsuccessful and the intruder persists, the male may rear his head back violently several times. He may also drop on all fours and charge toward the intruder. In general, when they charge they do not hit the intruder. Instead, they merely pass them by. This demonstration of aggression maintains order among separate troops and reduces the possibility of injury. It is thought that size plays an important role in determining the winner of an encounter between males (the larger male wins). Because of gorilla variability, some or all of these behaviors may not be seen.

OFFSPRING: 

Females reach breeding age at about 10 years old. They typically bear young every four to five years, giving birth after a gestation period of eight to nine months. Young gorillas cling to their mother's chests until they are old enough to ride on her back. A young gorilla remain with its mother until 5 years of age.

THREATS: 

Habitat destruction and poaching pose serious threats to the future of this species.