Gorillas are ground dwelling, predominantly herbivorous apes inhabiting the forests of Central Africa. These gorillas are divided into two species: that is, the Eastern gorilla and the western gorillas; which are also subdivided in four or five subspecies. They are considered to be the largest living primates having almost the same DNA as humans, which range between 95%-99% depending on how it is being described.
Gorillas are next to the two homininae species: chimpanzees, Humans, who are all believed to have originated from a common ancestor, 7 million years ago, having a difference of 1.6% between human and gorilla genes. These genes had several copies but previously, it was believed that they are of a single species with three subspecies: the western lowland gorilla, the eastern lowland gorilla and the Mountain gorilla .Today we only have two species as agreed; each having two subspecies. However, a third sub species has been identified in one of the species hence both species and the subspecies are considered to have developed from a single type of gorilla during the Ice Age, when the forest habitat shrank and became isolated from each other.
The third subspecies which has not yet got atrinomen is the Bwindi Population of the mountain gorillas, also known as Bwindi gorillas. Gorillas have got distinguished characters that are characterized according to their: varying density, size, hair color, length, culture and facial widths.
Female undergoes agestation period of eight and ahalf after which an infant is born, breastfeeds for three years and then stay with their mother for about 3-4 years.The infant crawls for around nine weeks and later walks after 35 week s old.The infants then mature at the age of 8 to 12 years.
- Females macure at 1o-12 years and males at 11-13 years
- Live in groups called troops
- Their lifespan is mainly between 35-40 years nwhere as those in zoo may leave upto 50 years
- Gorillas are highly intelligent that is they can laugh grieve,have emotional feelings,develop strong family bonds
- The Mountain Gorillas are the darkest of all the gorillas
- The Eastern gorillas are darker than the Western gorillas
- The Western lowland gorillas can be brown or greyish with Reddish fore head
- The eastern gorilla has longer face and broder chest than the western gorilla
- The ones that live in lowland forest are slender and agile than the bulky gorillas
- The mountain Gorillas have the thickest hair
- Their blood is not reactive to anti-A and anti-B monoclonal antibodies
- Adult males have prominent sagittal crest
- They Knuckle walk
- Sometimes walk bipedally for shorter distance while carrying food or used for defensive mechanism
- Wild adult Male gorillas weigh 135-195 kilograms.
- Female gorillas are shoter wit h small arm spans
- The facial structure is defined as “mandibular prognathism” meaning “the mandible protrudes further out than the maxilli.
Types of gorillas
Gorillas are categorized in to thre groups, which include:
The mountain gorillas are referred to as the descendants of ancestral monkeys, found in Africa and Arabia.Mountain have been isolated from Eastern lowland gorillas 400000 years ago.Their fur is often thicker and longer which enables them to live in colder temperatures . Each gorilla individual can be easily identified by nostrils. The males weigh 195kgs having more pronounced bony crest on top and the back of their skulls giving their heads a more conical shape ,while the females weigh 100kgs which is twice that of the males, also having crests but are less pronounced. The adult females have posses dark brown eyes framed by a dark ring around their Iris.
A saddle of grey or silver-coloured hair developes on the backs of the male adults as they grow old hence being called silver backs. The fur on their backs is always shorter than those on the other parts of the body but the air on the arms are extremely long. The fully developed males have a height of 1.7m with an arm spanning 2.3m, weighing about 155kg.
The mountain gorillas are programmed in that most of their activities are done between 6;00am -6:00pm, as many of these hours are spent eating in bulk n order to sustain their massive bulkiness.They go hunting very early in the morning, rest during the mid morning and then get back to hunt in the afternoon before resting again in the night. The gorillas often build their nets in the evenings to sleep in. Each gorilla has aduty of constructing a nest every evening but the case is different for the infants who are allowed to sleep with their mothers in the same nests.The gorillas leave their nests as early as 6:00am when the sun rises except when it is cold and overcast,then they will stay a little bit longer In their nests.
The mountain gorillas inhabits the Albertine rift montane cloud forests and of the virunga volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft). Most are found on the slopes of three of the dormant volcanoes: Karisimbi, mikeno and visoke.These forests are often dense at the bottom and sparse at the top. The mountain gorillas often live in forests which are:misty, cloudy and cold.
The mountain gorillas are herbivores, in that they highly feed on leaves, shoots and stems(85.5%) of 142 plant species. It also feeds on a bark(6.9%), roots(3.3%), flowers (2.3%), fruits(1.7%), and invertebrate(0.1%). Adult males can eat up to 34kg of vegetation a day while the females eat as much as 18 kilogrames. The mountain gorillas spends most of its time in most of its time in the hagenia forest where gallium vines are found all year round.it travels to the bamboo forest during the few months of the year when the fresh shoots are available and they would climbs into the sub alpine regions to eat the soft centers of giant scenecio trees.
The mountain gorillas are highly social and live inn relatively stable groups, held together by long term bonds between the males and the females.Although the relationship between females is very week, A silver back in a given group of females will always defend his group but not his territory thus, these groups are non territorial.
Of the groups composed, 61% comprises of one adult male and several females,36% has more than one male while the rest comprises of either lone males or exclusively male groups( where there is only one adult male and the others are young males).Here group size ranges between 5-30, with a mean of 10 individual, having: one silver back,one or two blackbacks, who act sentries, three to four sexually mature females and three to six juvenlise or infants.
The mountain gorillas are generally shy and gental although they are strong and powerful. Stable groups seldom undergo severe aggressions unless two mountain gorilla groups collide, then the two silver backs from either groups will engage into afight to death by using their canines to ause deep, gaping injuries and these conflicts can only be resolved by displays and other threat behavious that are intended to intimidate without becoming physical.The ritualized charge display is unique to gorillas and the entire sequence has nine steps: Progressively quickening hooting, symbolic feeding, rising bipedally, throing vegetation, chest-beating with cupped hands, one leg kick, side ways running four legged, slapping and tearing vegetation and thumping the ground with palms.
Establishments and reinforcements of relationships amngst te once conflcting groups is always done during the midday rest period.Mutual grooming reinforces social bonds and helps keep hair free from dirt and parasites. The females always groom their youngones. Since the younggorillas are mre aboreal than the adult males, the young have often played because it helps them to learn how to communicate and behave within the group,They engage in : wrestling, chasing and summer saulting while the silverback and his females tolerate but can particiopate if encouraged
Due to their intelligence, the gorillas have always used classified sounds such as ; grunts and barks for group communication and indication of the whereabouts of the group members, when travelling within the dense vegetation. These sounds are also used for social intarractions to maintain discipline.Other sounds like screams and roars are used as signal alarms or warnings and are often produced by the silver backs; the deep rumbling belches suggest contentment and are frequently heard during feeding and hunting period.
However , the mountain gorillas that have been studied appear to be naturally afraid of certain reptiles for unknown reasons, that even the infants whose natural behavior is to chase any thing that moves, will always go their way to avoid chamileons and caterpillers . They also fear getting wet that is why they cross over fallen logs when crossing streams.
The Eastern Lowland Gorillas
The eastern lowland gorillas also known as the Grauer’s is one of the largest subspecies of the four subspecies endemic to mountainous forest of eastern Democratic republic of congo. Most of these gorillas live in the Kahuzi-Biega and Maiko national park and their adjacent forests; Tyna Gorilla Reserve, Usala forest and on the Intombwe Massif.
The eastern lowland gorllas are the largest species of Gorillas and largest living primates having jet black coats like the mountain gorillas although the hair is shotter on the head and on the body. The males back turns silver as they mature.
The males weigh 204-250 kilograms but exceptional males weigh 272kilograms, al with astajnding height of 1.76-1.94 meters(5.8-6.4ft) or more as females also usually weigh half as much as the males with a standing height of 1.6 meters(5.2ft) or less.
The eastern lowland gorillas form large stable groups in form of families which lust for months or even ayear and spend long hours feeding on plant matter everyday .They can be found in Mountainious , transitional and lowland forest because of heir widest altitudinal range.On the highlands of Kahuzi Biega lives the most studied eastern lowland gorilla population where habitats vary between dense primary forests to moderately moist woodland to Cyperus swamp and peat bog.
Easten lowland gorillas have a lot of plant diet varieties to eat which include: fruits, leaves, stems and bark as well as insects such as termites and ants(form aminor part of the diet).They also enjoy the nutritious pith in the bananas, which is the main reason as to why most gorillas are killed by farmers in their banana farms. This is because the gorillas always destroy the banana plant in search for the pith, although after killing, the farmers enjoy double profit.
In terms of behavior, they are highly known to be social an peaceful in their groups which ranges from to 2-30 individual members, where by each group comprises of: asilver back, several females and their offsprings. Silverbacks are strong and each group has one dominant leader who protects their group from danger and the young silver males will slowly begin leaving their natal group when they reach maturity.
The number of these gorillas have declined due to different reasons:
- Poaching for meat
- Killing gorillas as a revenge for confiscation of illegal charcoal or other law enforcement
- Destru ction of habitat as aresult of logging, charcoal, agricultural expansion or mining
- Range reduction because due to an expanding human population
- Civil wars in Democratic Republic of Congo
Western Lowland gorillas
This is the smallest subspecies of the western gorillas that lives in Montane ,primary and secondary forests and lowland swamps in central Africa , in Angola, Cameroon, central African republic,The Republic of Congo, democratic Republic of Congo, Equatorial guinea and garbon.It is also the nominal species of the western gorilla and the only gorilla type kept in the zoo.
Althoughit is the smallest subspecies of gorillas, they are of exceptional size and strength and exhibits pronounced sexual dimorphism.They have no tails yet they have jet black skin along with long black hair that covrs their entire body except , for the faces, ears, hands and feet.The hair on the back and the rump of the males takes the grey coloration which gradally disappears as they grow older. This coloration is the main reason as to why the older males are called”silverbacks”. Just as humans,the hands of the gorillas are proportionately large with nails on alltheir digits,and also have large thumbs.They have short muzzles, prominent brow ridge, large nostrils small eyes, ears, large muscles in the jaw region withstrong and broad teeth . among these teeth, are strong sets of frontal canines and large molars in the back of the mouth for grinding vegetables.
An upright standing male can be 1.5-1.8m tall and weighs 140-270 kilograms but according to guinness book of world records, the average weght of the male is 168kgs with aheight of 163cm. The males in captivity are noted to be capable of reaching 275kgs while females stand aheight of 1.5m tall weighing half as much as males. Western gorillas frequently stand upright, but walk in ahaunched, quadrupedo fashion, with hands curled and knuckles touching the ground .The style of their movements require long arms, because the arm span is larger than their standing height,The average size of the male reproductive organ is 30-40cm and it stops growing after two years of age.
The western gorilla groups travel within a home range averaging 8-45 square kilometers.They are non territorial and consider and neighboring groups often overlap ranges as they usually favors certain areas within the home range, but seem to follow a seasonal pattern depending upon the availability of ripening fruits and localized large open clearings on some sites.
The gorillas normally travel for 5-3km per day and they feed on high energy foods that vary spartialy and seasonally tending to have greater ranges than those feeding on lower quality but consistently a vailable ranges, available foods
Larger groups travel greater distances so as to obtain enough food, as well as human hunters and leopards also affects the movement of their patterns.
Research tells us that it is easier for males to travel alone and also between groups as a result of solidarity they experienced before forming their own their own group.Males always leave their natal group to go through a bachelor stage that can last several years either in solitary or non breeding group, before reaching sexual maturity maturity age. Although both sexes leave their birth groups, the females will never move alone but can move from one breeding group to another.The males also like to settle with other males of the same family.Their group consists of : one silver back, three adult females and one offspring as the male gorilla becomes the protector . The females also make bonds with other females of their groups but make stronger ones with the males as the males highly compete for contact with females.
The group is led by one or more males. In most cases where there are more than one silver back In a group, you are most likely to find a father and as on in a group, and those having only one male are believed to be the basic unit of the social group, gradually growing in size due to reproduction and immigration. According to he studies done at Lope, gorillas harvest more food compared to the construction of their nests from which half of their night nests are built on trees ,in that they are found on the ground and are made up of thirty gorillas.
Western lowland gorillas live in a smallest family group of all gorillas with an average of 4-8 members in each group and the silver back is responsible for the organisation of the group activities like: nesting,, eating and travelling in their home.
However, gorilla are non aggressive and calm unless they are disturbed.
The females do not produce many offspring due to the fact that they do not reach the sexual maturity until the age of 8-9.Their captivity is approximately 5 or 6 years and the males are considered mature at the age of 15 years.Their gestation period lusts for only 9 months after which they give birth to tiny newborns who only cling on the fur of their mothers since they weigh 4-5 pounds.These infant are depend on their mothers in that they ride on their ’ backs for about 3-4 years.
Western gorillas mainly feed on roots, wild celery, fruits, shots , tree bark and pulp largely provided by the thick forest of central and western forest.During wet season , there is high consumption of of fruits whereas in the dry seasons, these fleshy fruits become scarce and therefore the gorillas resort to other options of other kinds of fruits. Their feeding habits is divide into three: staple food; eaten on daily /weekly basis all annually; seasonal foods –available in large quantities during its season and scarce out of the season and fallback food-available at all times. . During Dry season , the gorillas prefer to eat herbs(protein rich- leaves) and bark, as they are able to climb up to 15 meters I search for what to eat. Gorillas feed on fruits reach in fiber and high in sugar to give them energy, and disperse seeds in their dung.The male gorillas travel further in search for fruits during wet season and spend time on the ground eating herbs in the dry season while the females eat more leaves than males and normally feed higher in the trees.
The gorillas can eat more than 97 plant species and the amount of food that can sustain their bodies about 18 kgs.
The Western lowland gorillas inhabit the : rain forest, swamp forest brush, a abandoned farming fields riverine forest and secondary vegetation. The swamp forest is highly recognized habitat for the western lowland gorillas because of its strategic position in that it does not show the signs of human activity and is away from the road since gorillas fear places with roads and are also suitable for both season and wet season. Today, majority of the gorilla population are being hosted in the Republic of Congo forests, a place favorable for the protection of the gorillas which is highly isolated from the the large swampy forest ares.
Gorilla Distribution and habitat
Gorillas have patchy distribution with the Congo river and its tributaries separating the range of of the two species. The western and the Eastern gorillas live in the west and East central Africa respectively.The gorillas live in a variety of habitats and elevations which ranges from montane forests to swamps.
Eastern Gorillas inhabit the Montane and sub-montane forest ranging between 650 and 4000m above sealevel; the Eastern lowland gorillas live both in the sub montane forests at gthe lower ends of the elevation range, and also in montane bamboo forests as well as lowland forests ranging from 600-3308m in elevation. Western gorillas live in both:lowland swamp forest and and montane forests whose elevations range from sealevel to 1600m. they also live in swamps and lowland forests ranging up to 1600m; the mountain gorillas live in the montane forest at the higher ends of the elevation range and the cross river gorillas live in low lying and sub montane forest ranging from 150 -1600m.
Gorillas contruct their nests purposely for daytime and night use.These nests tend to be asimple combination of branches and leaves of about 2-5 ft in diameter and are constructed by individuals.the gorillas tend to sleep in the nests on the ground and the young nests with teir mothers but are able to construct ttheir own after three yearsof age but close to that of their mothers.
Just like humans,gorillas are always programe their day schedules, divided between rest , travel and feeding periods. Their diets also differ between species in away that mountain gorillas eat foliage such as ;shoots,stems, leaves and piths, while fruits is less needed in their diet.Their food is extensively distributed that no group or family ever competes for.
The eastern lowland gorillas have a more distinctive diet which vary seasonally but leaves and piths are commonly eaten and western lowland gorillas prefer frits compared to all other fruits and have less access to terrestrial herbs although they have acces to acquatic herbs .hey also consume termites and ants.
Gorillas rarely drink water because they consume succulent vegetation that contributes about 50% water as well as the morning dew, although both lowland and the mountain gorillas have been observed drinking water.
The chimpanzees/ chimps as well as the bonobos are part of the Hominidae family, both of which are restricted currently in the African ranges , and are found in the congo jungle.The common chimpanzee are also found far north of west Africa
The chimps and the bonobo were once considered to be of the same species, but in 1928, the y were found to be of different species due to their comparisons and contrasts such as
|Known as P. troglodytes||Known as P.paniscus|
|Live North of congo River||Live south of congo river|
|Divided into four species||Noy divide|
|The are larger, aggressive and male dominated||More gracile, peaceful and female-dominated|
However, bothe of parties have similarities such as:
- Both have typically black or brown hair
- The sizes of the males is totally different from that of the females
- Social bonds occur among their large individual communities
- Both can live for over 30 years both in the wild and in captivity
- Both are humans closest living relatives.
- Both have the largest brains and most intelligent of all the primates
- They use sophisticated tools to build elaborate sleeping nests each evening from branches and foliage.
- Both are being studied for their learning abilities
- Their exists distinctive cultures within the cultures
- Their activities are considered to be endangered as those of the humans
The chimps possess long er arms spanning one and a half times the body height when extended, compared to the legs.The common male chimps are 1.2m(3.9ft) tall, with the wild adult males weighing 40-60kg while the females are 27-50kg. Like the gorillas, te chimps also walk on four(knuckle walk), squeezing their fists and supporting them on the knuckles. The chimps like the bonobos are commonly known for walking on their two legs when carrying objects in their hands.
The chimpanzees posses the following characteristics:
- They have no tails
- They have dark coats
- Hairless; face, hands, feet , palms of the hands and soles of the feet
- The colour of the displayed skin of the face, hands and the feet range from pink to dark
- The receding appearance of the forehead is as a result of a bony shalf over the eyes
- They have flat nose
- Posses protruding jaws
- The lips thrusts out only when it pouts
- The brain ranges from 282-500cm3
- The females reach puberty between the age of 8-10 years
- The males’ testicles are usually large suitable for its size, with a combined weight of about 4okg
- The captured chimps can live up to 70 years older while those in the wild live an average of 30 years.
- They posses great amount of muscle strength which is thought to come from longer skeletal muscle fibres that can generate twice the energy out put over a wider range of motion.