Gorillas are great apes, predominantly herbivorous inhabiting the tropical forests of central Sub-Saharan Africa. Gorilla is a genus name with two broad species, the eastern gorilla and the western gorilla which are further divided into two subspecies each. These are; western lowland gorilla, cross-river gorilla, eastern lowland gorilla and mountain gorilla.
Gorillas are the largest living primates and the largest non-human apes whose height ranges between 1.25 and 1.8 meters and weigh between 100 and 250 kilograms. They are the next closest living relatives to humans after chimpanzees and bonobos, sharing about 98% of our DNA. Due to this close genetic relationship with humans, gorillas display many human-like behavior and emotions such as laughter, sadness, and relationships.
Gorillas have broad chests and shoulders, large human-like hands with small dark eyes set on hairless faces. They live in groups of about 5 to 10 though this can vary from as low as 2 to 50 depending on several factors like type and habitat. Each group is led by an adult dominant male known as silverback. One silverback presides over several females with their offspring in one group, leading them into their daily activities which include foraging, movement, playing, resting and nest building.
Female gorillas become sexually active at around 7 years but don’t begin to breed until a couple of years later while males mature late usually after their 12th birthday. Females give birth to one baby every four to six years and on average they produce 3 to 4 offspring in their lifetime. The low reproduction rate among gorillas is one of the major factors responsible for their declining population.
International conservation organizations and governments are working hard to save gorillas and so far, success has been registered with mountain gorillas whose population has been increasing in recent years. Due to their steady population increase, in 2018, the status of mountain gorillas was upgraded from critically endangered species to the endangered category.
Cross River Gorilla
Cross river gorilla is a subspecies of the western gorilla found in forests around the Cross River along the border of Cameroon and Nigeria. Researchers estimate that there about 200 to 300 cross river gorillas left in the world. However, establishing the real population of these critically endangered gorillas has been really hard due to the difficulty in accessing them since they inhabit a rugged territory and are also wary of humans. Scientists have tried to use other indirect signs to estimate their number which include nest counts and range sizes. Study shows that cross river gorillas are divided into at least 11 groups which are scattered across the lowland montane forests and rain forests of Nigeria and Cameroon.
Cross river gorillas have a similar appearance to the western lowland gorillas but the most significant difference is found in the skull and tooth dimensions. Human encroachment for cultivation land, timber and settlement is one of the major factors that have hindered the increase of cross river gorillas’ population. Poaching is also carried out in forests where these animals live which has reduced their numbers the more.
Conservation organizations are partnering with the governments of Cameroon and Nigeria to create a protected area for cross river gorillas.
Western lowland gorilla
The western lowland gorilla is the most numerous and widespread of all gorilla subspecies with its population found in a number of west African countries. They can be found in Cameroon, DR Congo, Central African Republic, Equatorial Guinea, Gabon and Republic of Congo. Western lowland gorillas inhabit some of the most dense and remote rain forests in west Africa which has made establishing their exact number extremely difficult.
Key aspects that distinguish western lowland gorillas from other subspecies include their slightly smaller size, auburn chests and brown-grey coats. Their skulls are also wider with more pronounced brow ridges and smaller ears. Though they boast a larger number compared to other gorilla subspecies, their population has been declining over the past 25 years by more than 60 percent. This is basically due to poaching and disease and scientists calculate that it would about 75 years to recover their lost population.
Eastern lowland gorilla
The eastern lowland gorilla, also known as Grauer’s gorilla is the largest of the four gorilla subspecies and can be found in the lowland tropical rainforests of eastern DR Congo. Its large hands, short muzzle and stocky body are its key distinguishing features from other gorilla subspecies.
Common factors like human encroachment, poaching and civil unrests have taken their toll on the eastern lowland gorilla too just like other subspecies. Their population was estimated to be nearly 17,000 in the mid 1990s but it has since declined by more than 50%. Their habitat has also decreased from 8,100 to 4,600 square mile in the last 50 years. Violence in the eastern DR Congo has made an accurate accounting of the eastern lowland gorillas impossible for over two decades.
Nonprofit conservation organizations like WWF, Dian Fossey Fund are working hand in hand with the Congo government to establish control over the gorilla habitat.
Mountain Gorilla
The mountain gorilla is the second least in number of all the four gorilla subspecies with its population estimated to be around 1,063 individuals. It’s population is split into two separate groups with one living in the Virunga Mountains, a range of extinct volcanoes that straddles the borders of DR Congo, Rwanda and Uganda. The other group is found in Bwindi Impenetrable National Park in southwest Uganda.
Mountain gorilla population has endured years of war, poaching, disease and habitat destruction since the discovery of the subspecies in 1902. These threats became so severe to the extent that the subspecies was once thought that it might be extinct by the end of the twentieth century.
Mountain gorillas have a lot of thick fur compared to other gorillas and this enables them to adapt well with the cold temperatures at higher altitudes where they live. Increased human encroachment on their habitat continued to push these gorillas further into the mountains where they are forced to endure even harder conditions.
Gorilla tourism is more pronounced with mountain gorillas with wildlife authorities in the 3 countries having successfully managed to habituate several wild gorilla groups for tourism. Thousands of travelers book for gorilla safaris to visit and trek these habituated gorillas in their natural habitats. Due to conservation demands, visitors are permitted to spend one hour in the presence of mountain gorillas once they reach them. Governments in all the 3 countries are working together with conservation organizations to ensure that mountain gorillas and their habitats are well protected. This has greatly produced positive results with the subspecies population steadily increasing over the past couple of decades. Today mountain gorilla is the only gorilla subspecies whose population is increasing.