In A Nutshell
There are two different subspecies of gorilla that are often lumped into one. There are distinct differences, though; the mountain gorilla is larger, with longer hair and shorter arms than their lowland gorilla cousins. Lowland gorillas are much more likely to be seen in the trees, and prefer a more heavily forested, flatter habitat than the mountain gorilla.
The Whole Bushel
As their names suggest, the two subspecies of gorilla have very different habitats. The lowland gorillas make their homes in the thick rain forests on the Atlantic Coast of Africa. They have a relatively small area that they still live in in the wild, including untouched wilderness in Congo, Equatorial Guinea, Central African Republic, and Cameroon. The mountain gorilla is found at much higher altitudes and much farther inland, surviving in a pocket of wilderness in Rwanda, Uganda, and the Democratic Republic of Congo. Most of their native habitats are the rocky slopes of once-active volcanoes, although they are known to venture into the high, alpine regions of the mountain ranges where they can face freezing temperatures.
Mountain gorillas are the largest of all primates, with males ranging from 135–220 kilograms (300–485 lbs) and standing between 1.2–1.8 meters (4–6 ft) tall. Lowland gorillas tend to be a bit smaller than their mountain cousins, weighing between 65–180 kilograms (150–400 lbs). Females are always considerably smaller than males, usually weighing about half as much.
Both subspecies live in family groups called “troops.” Large troops with as many as 30 individuals have been seen, but the usual makeup of these families is quite a bit smaller. A gorilla troop usually consists of one dominant male, a handful of his females, and their immature offspring. Adult male children will split off from their family unit to travel alone; around the age of 15, males will begin collecting their own harem of females and start their own family group. Between leaving their parents and collecting females of their own, immature lowland males will occasionally form their own troop, sometimes attached to a parent group.
Dominant, mature males of both subspecies will show the familiar graying of the fur on their backs; this usually occurs at about 13 years of age, a few years before they begin to breed. Lowland gorillas tend to have much shorter hair than mountain gorillas and aren’t as darkly colored. While mountain gorillas range in color from bluish-black to dark, brownish-gray, lowland gorillas tend to have a lighter, more brown or gray coat. Elderly male lowland gorillas often lose the gray hair on their back and hips.
There is some difference in the physical features between the two, although it can be hard to distinguish at a glance. Both have very long arms—their arm span is longer than they are tall—but mountain gorillas typically have shorter arms than their lowland cousin. They also have a larger nose and jaw, and larger teeth.
When stressed or upset, male mountain gorillas emit a strong odor from glands under their arms. Studies of lowland gorillas have so far shown that scent communication doesn’t play as large a role in their culture.
While both subspecies can climb trees and both are known to make nests in trees of branches and leaves, lowland gorillas are much more likely to be seen traveling through the trees. They’re also much more likely to be seen in the trees searching for food; both subspecies are herbivores, and the lowland gorilla will commonly be seen high up in the trees stripping bark and leaves.
Both subspecies are also considered endangered. The lowland gorilla is frequently hunted for skins, and there is a high demand for their meat. Because of the location of the home territories of the mountain gorilla, they are often accidental causalities of civil war in addition to being pressed out of their land by the transformation of land from wild habitat to something more suitable for human occupation.