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5TF: 5 Things You Didn’t Know About Mountain Gorillas (Gorilla beringei beringei)!

Fact 1

Mountain gorillas live in the most extreme environment of any of the four gorilla subspecies.

Mountain gorillas are unique to a small section of central Africa. They are only found in the Virunga Massif, which is comprised of three parks that are found in the countries of Rwanda (Volcanoes National Park) Uganda (Mgahinga National Park) and DR Congo (Virunga National Park) and Bwindi Impenetrable National Park, located in Uganda. These two ranges total less than 300 sq miles. This is about 10 times smaller than Yellowstone, which is 3,488 sq miles. They reside at the highest elevation (up to 4,500 meters) and coldest temperatures, and have the least amount of fruit available to them compared to any other type of gorilla.

Fact 2

Mountain gorillas have thicker and longer hair than other gorilla subspecies.

This is an adaptation to the cold temperatures of their mountain environment, where temperatures sometimes get below freezing! 

Fact 3

Mountain gorilla’s diet is high in tannins.

Like all other gorilla species, mountain gorillas are herbivores and consume a plant-based diet of leaves, roots, bamboo, bark, bamboo shoots, as well as seasonal fruits and flowers. But, due to the high elevations at which mountain gorillas live, particularly in the Virunga Massif area, they consume less fruit than other gorilla species. As a result, their diet is high in tannins.  In fact, these are the same compounds that make your daily cups of tea and coffee bitter. Just like drinking coffee will stain your teeth over time, the mountain gorillas’ teeth are stained to almost black by their high tannin diet. Check out the image of Icumbi below showing off his tannin stains!

photo illustrates the effects of tannins

Fact 4

Mountain gorilla groups may have more than one silverback.

 Family groups of three of the four gorilla subspecies typically have only one adult male gorilla, known as a silverback. This silverback will act as the dominant individual in the group and make decisions about where to travel and when to stop, as well as protect the females and young gorillas.  However, around 40% of mountain gorilla groups contain multiple adult silverbacks! In these groups, there is a hierarchy among the males, and there is still a single male who is dominant over all other individuals (called the dominant or alpha silverback). Because males don’t transfer between groups (unlike females), subordinate silverbacks in a group were born into that group and at some point decide if they will stay and try to inherit dominance or if they will strike out on their own and try to attract females away from other groups to form their own family. Subordinate silverbacks share the job of protecting and directing the group, and while dominant males generally sire the majority of offspring, some subordinate males also reproduce.

Fact 5

Mountain gorillas are the only subspecies of gorilla whose population is increasing. 

While all other populations of great apes (except humans) are decreasing in size, the mountain gorilla population is actually increasing! Mountain gorilla numbers have consistently risen over the last 30 years. Gorilla census information is split between the Virunga population (living in the Virunga Massif) and the Bwindi population (living in Bwindi Impenetrable National Park). At the lowest point, the Virunga population dropped to approximately 250 individuals in the early 1980s, classifying them as critically endangered on the IUCN Red List. Today, the same population stands just over 600 individuals! The Bwindi population is increasing as well and is currently at 400 individuals. Due to this consistent increase, mountain gorillas have recently been reclassified from critically endangered to endangered, which is one step further away from extinction.  This incredible population recovery is a result of the conservation leadership of the countries where mountain gorillas are found as well as the work of conservation groups like the Dian Fossey Gorilla Fund and its team of trackers, researchers, staff, and donors!