Western lowland gorilla

Lore & Background

Western lowland gorillas exhibit pronounced sexual dimorphism, with males significantly larger than females. They have jet black skin and coarse black hair covering the body except the face, ears, hands, and feet. Older males develop grey hair on the back and rump, earning them the name 'silverbacks'. Their hands are proportionately large with nails on all digits and very large thumbs. They have short muzzles, prominent brow ridges, large nostrils, and small eyes and ears. They walk in a hunched, quadrupedal fashion with knuckles touching the ground, and their arm span exceeds their standing height. The only known albino gorilla, named Snowflake, was a wild-born western lowland gorilla from Equatorial Guinea. Genetic analysis identified a non-synonymous single nucleotide polymorphism in SLC45A2, a transporter involved in oculocutaneous albinism type 4 in humans. His parents were an uncle and niece who were both carriers, providing the first evidence of inbreeding in western lowland gorillas. Western lowland gorillas live in groups typically of four to eight members, led by one or more silverback males. Groups travel within a home range of 8 to 45 km², and they do not display territorial behavior. Females reach sexual maturity at age 8 or 9 and give birth to a single infant after a gestation of nearly nine months. Infants ride on their mothers' backs from four months through the first two or three years and may be dependent for up to five years. Infanticide by adult males has been observed, with victims never related to the killer.

Reader's Guide

The western lowland gorilla is significant as the most numerous and widely distributed gorilla subspecies in zoos, yet it remains critically endangered in the wild. Its intelligence is demonstrated by the ability to fashion natural materials into tools for gathering food, such as modifying branches to extract food from holes, showing sensorimotor intelligence comparable to young human children. The discovery of albinism in Snowflake and the associated inbreeding provided unique insights into gorilla genetics. The subspecies' social structure, with small family groups led by a silverback, and its non-territorial, seasonal movement patterns reflect adaptations to fluctuating food availability. Its reproductive biology, including non-reproductive sexual behavior among females and infanticide by males, illustrates complex social dynamics. The western lowland gorilla serves as a key species for conservation efforts and for understanding primate behavior and evolution.

Did You Know?

• The western lowland gorilla is the smallest of the four gorilla subspecies.
• The only known albino gorilla, Snowflake, was a western lowland gorilla from Equatorial Guinea.
• Female western lowland gorillas do not reach sexual maturity until age 8 or 9.