The life and habits of gorillas:
Despite the bad name and scary stories told about gorillas at the beginning of the 1900s, before scientists unraveled the mystery and life behind these gentle giants, gorillas have now become popular tourist attraction and creatures of the wild worth conserving
Gorillas are the largest of the large apes of the world in a group that includes chimpanzees and orangutans. Genetically, humans, chimpanzees and gorillas are closely related. We human share 97 per cent of the same genes with gorillas, 98 with chimpanzees. We also belong to the hominoidea within the order of primates. Other primates include monkeys, lemurs and bushbabies. Apes only differ from monkeys for not having tails, but with bigger brains.
Gorillas of Mghahinga and Bwindi are Mountain gorillas, he most rare of the three subspecies of gorillas. All gorillas stay extensively in forests of West and Central Africa. Mountain gorillas are found only in the Virunga Volcanoes and in Bwindi.
Way back at the turn of the 20th Century European explorers took home stories of ferocious creatures that bore little resemblance to the actual animals. Over 2000 years ago an explorer called Hanno from the city of Carthage in North Africa encountered some apes on the coast of West Africa where his men who tried to capture live specimens were mauled and wounded. In his language “scratcher” meant gorilla and although the apes he encountered may have been chimps, the name stuck.
Scientists first described gorillas as species in 1847. The largest specimen on record of gorillas was a lowland gorilla from Kahuzi-Biega in the Congo. Rumours about gorillas existing on mountains in Central Africa were only confirmed in 1902 after some were shot at Mt. Sabyinyo, by a German army officer called Oscar von Beringei after whom the mountain gorillas were later named.
In later expeditions, hunters killed more than 50 of them in the Virunga area for museum collections. They exaggerated their bravery in defeating the awesome monsters and later on, the King Kong motif was created. The gorillas have survived through lucky and adversity. Civil wars in Rwanda, Burundi, Congo and Uganda have all affected their lives.
Later on, research carried out by George Schaller in 1959 established the true nature of gorillas as gentle giants, peace loving and shy creatures. Other researches followed both on the Uganda and Rwanda side of the border as films and popular articles continued to be written about thee apes. One daring woman researcher Dr. Diana Fossey habituated a number of gorilla families at Karisoke in Rwanda in the 1980s and brought them to the attention of the world before she was brutally killed probably by the poachers she harassed for the good of nature. The research station she set up still stands today and continues with her good work.
In both Uganda and Rwanda, there have been concerted efforts to create awareness among communities living near the gorilla habitats the value of conserving them both for their benefit and good of nature. Before such campaigns were launched, more than 50 per cent of the communities wanted the parks to be converted into farmland but after the campaigns the opinion were tilted in support of conserving the forests with 70 per cent support.
The battle to support the survival of gorillas still continues. There are only about 600 mountain gorillas left, with half of them in Uganda and the live in a precarious environment of about 765 cubic metres, which is still not safe from encroachment by poaches and farmer who are hungry for land, mineral prospectors and smugglers who all use the forests for different purposes.Mountain gorillas have never been reared successfully in captivity and there are none in zoos. The good news is that they still exist in their forest homes in the Virunga and at Bwindi although they are on the critically endangered species list. There is only one mountain gorilla for every ten million people on earth.
Ecology
Gorillas a vegetarians. In the Virunga, they eat at least 58 different food plants, mostly leaves, stems and bark. Bwindi forest has more plant species than the Virunga. Its gorillas have been less studied but are know to eat less than 60 different plants and possibly including fruit. On some rare occasions, they eat insects, snail, nibble at soil or their dead infants.Most of what gorillas eat is found in the lush greenery of forest clearings and disturbed sites.
This might affect their existence. For example, the high altitude forests of the Virunga Volcanoes have a more open canopy with a luxuriant undergrowth which is well spread out in the forest. The gorillas there depend less on the disturbed sites and tend to have smaller home ranges than those in Bwindi, for example and other dense forests. Gorillas munch on juicy bamboo shoots, giant thistles, lobelias and crunchy wild celery. So, for most of the year the gorillas do not take water although they can be seen quenching their thirst at the edge of stream especially during the dry season, or licking water off their drenched coats during the heavy rainstorms.
The giant apes have a single stomach like that of humans and a rather long intestine which is not quite efficient in digesting vegetation like the multi-chambered one of the Colobus monkey and hoofed ruminants. They therefore have to consume large amounts of vegetation daily -about 20 kilos for adults- which makes them look bloated. They spend about 30 per cent of their time feeding, 30 per cent moving about and foraging and the rest of their time in slumber. They are the most earth bound apes since about 90 per cent of their time is spent on the ground.The daily routine is led by the male silverback in the troop who decided where the rest of the family should go. At dusk, each gorilla makes its own nest in which to spend the night but the nest is only used once. The nests are usually grouped around the male, with the infants sleeping with their mothers until they are weaned at the age of about 3-4 yeas. Gorilla walks can spread around 100 metres or more, especially if more silverback are present. Defecation takes place in the nests and often gorillas can sleep late, say when it rains or on some mornings, especially if they have traversed a long area.These beasts live in family groups of about 12 animals although they follow no set patterns in composition or size. Groups of more than 25-30 animals have been recorded, including smaller ones. Surprisingly there have been groups of males only, where weak relationships are established. They maintain their ties by avoiding conflict and on finding a female companion will leave the group. Social relationships among females are determined by kinship and bonds between females can be very strong.
Gorillas are not known to be territorial and on some occasions, family groups may overlap habitats which often attract male displays of chest thumping. During such occasions, some females may transfer from one family to another. It does not appear as if they have been snatched away from their original homes. Instead, it looks like it is a natural choice made voluntarily on their part. Of course, vicious fights take place with bites and tears which end up leaving ugly gashes on the victims. Males invading and taking over a family have been known to kill all the infants found there, while at the same time some apes have been known to tolerate and bring up as their own some infants found in families they have taken over.
Adults male make gestures, facial expressions and 16 well-known distinct calls. A charging bull can make a scary scream, followed by a belch-grunt or even a contact-call. Gorillas make very elegant and regale postures. Males will bare their teeth, walk stiff-legged, warning of increasing signs of aggression.
Male gorillas reach maturity at between 8-15 years while females do so at the age of eight although do not have their first baby until they are 10 years old. Mating behavior and sexual play by subordinate males is common. Subordinate males may actually mate more times than the dominant silverback who may ignore all this promiscuity, although he will monopolise females in the estrus period Males tell when the female is in estrus and that is when quarrels among males tend to increase. Pregnancy lasts 8.5 months, but signs for pregnancy can be difficult since gorillas are often fully engorged on vegetation meals and their bellies look distended anyway. Male gorillas are very caring father since they often play with infants and even look after those whose mothers have died. In a life of 50 years, a female should be able to produce 10 children, but with such high infant mortality rates, most mothers probably raise only about 4-6 offspring. So, the normal reproductive rate in the mountain gorilla is not high and outside factors such as disease, poaching, capturing of infants and other forms of stress seriously depress the numbers further.