9 Big Hairy Facts About Gorillas

Both species of gorillas — Eastern (Gorilla beringei) and Western (Gorilla gorilla) gorillas — are found in equatorial Africa. Although there are just two gorilla species, there are several subspecies: mountain gorillas, Cross River gorillas, western lowland gorillas and Grauer's gorillas. The eastern species lives at higher elevations on the green slopes of volcanic mountains, and the western species lives at lower elevations in tropical jungles.

"Each plays vital roles within their ecosystems, providing mechanisms for seed dispersal, as well as maintaining a balance within the food chain by consuming large quantities of plant material," says Josh Meyerchick, Lead Keeper in Primates at Zoo Atlanta, in an email interview.

Although adult male gorillas can weigh up to 430 pounds (195 kilograms), they didn't get that way by packing on the protein. Quite surprisingly, the amply sized gorilla eats just about the same diet as the much smaller hedgehog. Gorillas are mostly herbivorous — they eat around 140 different species of plants, and need to consume about 60 pounds (27 kilograms) of food per day. And although they get most of their calories from fruit and bamboo shoots, they definitely won't turn up their nose at a caterpillar, a termite mound or a small animal.

"It's hard to grasp how powerful these animals truly are until you are up close to them and observe a display behavior," says Meyerchick. "Listening to a full-grown adult perform a crescendo by slamming his open palm on the surface of a reverberating object is an experience that would make many people jump."

Gorillas are generally quite gentle with each other and rarely pull out all the stops, strength-wise. However, an adult gorilla is certainly very strong — possibly up to 10 times stronger than a grown man. Gorillas have been known to bend metal bars to escape a cage, tear down banana trees with ease and their bite has about double the force of a lion's.

Gorillas sleep at least 12 hours a night, and they take their bedding seriously. Gorillas make a new bed almost every single night — in fact, it's estimated that they reuse a previous night's bed only about 4 percent of the time. It takes them about five minutes to make a new nest — usually on the ground, but sometimes elevated in a tree — and they occasionally even make day nests. Baby gorillas share their mother's nest until they're about 3 years old or until she has another baby, and the nest is the place where they sleep, play, snuggle and are groomed by their mothers.

Gorillas live in groups called "troops," usually made up of one silverback male (an adult male reaches sexual maturity around 12 or 13 years of age, at which point he develops a silver patch of fur on his back) and at least one female, but usually more. The silverback mates with all the females in the troop, even when younger males are tolerated by the silverback and allowed to stay in the group. A troop can occupy a territory of up to 16 square miles (41 square kilometers), and they spend much of their time wandering around, eating, grooming each other, playing and maybe even arguing. The silverback is in charge of figuring out where the troop goes, resolving conflicts between other gorillas, finding food, etc. When the silverback dies, the troop generally disperses, although sometimes a new silverback will swoop in and take a deceased silverback's place in a troop.

Gorillas you see in zoos exhibit most, if not all, behaviors observed in their wild counterparts. They build nests, have the same social interactions, forage for and process food, use tools and vocalize in the same ways, even when they're being cared for by humans.

"Gorillas in zoological populations, such as those at Zoo Atlanta, have the added behaviors of interacting with their care team within voluntary positive enrichment training programs," says Meyerchick. "These programs allow gorillas to participate at their discretion in procedures that allow for increased overall animal well-being. For instance, gorillas can present body parts for physical checkups, receive voluntary injections such as flu and tetanus vaccines, and even present their chests for voluntary echocardiograms to monitor heart health. All of these enable the gorillas to participate in their own care."

Gorilla researchers — the famous Dian Fossey among them — have often noticed each silverback has its own, distinctive pungent aroma. A 2014 study in the journal PLOS One suggests that a silverback uses this fragrance to communicate his position in the group, but he can just as easily "turn off" the scent if he wishes to hide or doesn't need to exert his authority at the moment.

Although the gorilla is the largest primate currently living on Earth, there once was one much larger. The prehistoric Gigantopithecus was 10 feet (3 meters) tall and 1,100 pounds (500 kg) and lived in what's now southern China until it went extinct about 100,000 years ago. According to a 2017 study published in the journal ScienceDirect, its size was probably its downfall. During a shift in climate during the Pleistocene, forests turned to grasslands and Gigantopithecus wasn't able to find enough food to survive the changes in its ecosystem.

"Gorillas face numerous threats in the wild, from disease to the bushmeat trade, but habitat loss hits their populations especially hard," says Meyerchick. "Agriculture, forestry and mining push gorilla populations into smaller and smaller tracts of land."

Only about 1,000 endangered mountain gorillas live in the wild — but that number has doubled from what it was 30 years ago. Western lowland gorillas have higher number — over 100,000 individuals live in the tropical forests of central Africa — but they are considered critically endangered by the International Union for Conservation of Nature (IUCN).

"It is important to note that population numbers are not the only factor when determining the vulnerability of a certain species — having an appropriate amount of space to survive is also a critical factor," says Meyerchick.

The comeback of the mountain gorilla has shown conservationists that success is possible when it comes to bringing gorillas back from the brink of extinction.

"Zoo Atlanta is a longtime partner with The Dian Fossey Gorilla Fund International (DFGFI), an organization working to save wild mountain gorilla populations," says Meyerchick. "The success is measurable, as mountain gorillas have been reclassified from critically endangered to endangered. Mountain gorillas are the only great ape species whose wild populations are increasing, and it is due in large part to conservation organizations such as DFGFI and the support they receive from organizations such as Zoo Atlanta."