Silverback gorillas are an iconic presence in the forests of central and eastern Africa, known for their imposing stature. The term “silverback” refers to mature male gorillas, distinguished by the patch of silver hair that develops on their backs as they age. This physical attribute signals their adulthood and often their leadership within a gorilla troop.
Key Physical Dimensions
Silverback gorillas are the largest living primates, possessing substantial height and weight. An adult male typically stands between 1.4 to 1.8 meters (4 feet 7 inches to 5 feet 11 inches) on all fours. When standing upright, their height can reach 1.67 to 1.83 meters (5 feet 5 inches to 6 feet), with some individuals recorded as tall as 1.95 meters (6 feet 5 inches) in the wild. This considerable height is accompanied by impressive mass.
Wild silverbacks usually weigh between 136 to 227 kilograms (300 to 500 pounds), though average weights can vary slightly depending on the specific subspecies. The heaviest wild silverback on record weighed 267 kilograms (589 pounds). For comparison, an average adult human male stands approximately 1.75 meters (5 feet 9 inches) tall and weighs around 77 kilograms (170 pounds).
Silverbacks also possess an exceptionally broad arm span, ranging from 2.3 to 2.6 meters (7 feet 7 inches to 8 feet 6 inches). This arm span is significantly greater than their standing height, adapted for their quadrupedal locomotion and foraging behaviors. Their robust build includes a large chest; a recorded wild silverback had a chest circumference of 1.98 meters (6 feet 6 inches).
Factors Influencing Size
Several biological and environmental factors contribute to the substantial size of silverback gorillas. Age plays a significant role, as male gorillas do not reach their full adult size until they are between 15 and 18 years old. The distinctive silver hair on their backs typically emerges around 12 to 14 years of age, marking their transition into the “silverback” stage, at which point their musculature also becomes more developed.
Their diet is another major determinant of their size. Silverback gorillas are primarily herbivores, consuming vast quantities of vegetation daily. Their diet consists mainly of leaves, stems, bamboo shoots, and various fruits, with occasional consumption of insects for additional nutrients. To sustain their massive bodies, they consume between 13.6 to 27 kilograms (30 to 60 pounds) of plant matter each day.
Genetic predispositions also contribute to their growth potential. Males exhibit pronounced sexual dimorphism, meaning they are considerably larger than females, sometimes even twice their size. Variations in size exist among different gorilla subspecies, with Eastern gorillas generally being larger than Western gorillas. Environmental conditions, such as climate, can indirectly influence size by impacting the availability and quality of food resources. For instance, mountain gorillas living at high altitudes may develop a larger thorax as an adaptation to reduced oxygen pressure.