who where how why hope why

how do they behave?

  • Intro
  • Silverbacks
  • Females
  • Infants
  • Eating
  • Sleeping
  • Locomotion
  • Communication
  • Intelligence

Mountain Gorillas are shy, social animals whose lives are generally peaceful and quiet. They live in family groups of between 2 and 40 members. The average group contains 10 or 12 animals. Of all the great apes, gorillas have the most stable family groups. Each group usually consists of 1 dominant silverback, at least one blackback, several mature females, a few young adults and juveniles, andgorilla family several infants.

Mountain gorillas spend about 30% of their day eating, 30% traveling and playing, and 40% resting and sleeping. A typical day in the life of a mountain gorilla group will see them rise at daybreak to travel and feed in the morning. They may feed as they move, but will usually find an open area where they can spread out and eat at a leisurely pace. They will take a long rest at midday when they can be seen lounging around, tolerantly fending off boisterous infants and farting continuously and contentedly. The whole afternoon will have them again moving and eating before bedding down at dusk.

Large adult males called silverbacks head their family groups. Silverbacks are named for the distinctive patch of silver or gray hair on the small of their backs, or “saddles”. This graying happens gradually as they get older, just like the hair on the head of an older person. This may be in order to intimidate his enemies, silverbackby making him appear larger than he really is. When a solid block of color is broken up with another color in the middle, the object seems longer in an optical illusion.

Silverbacks are strong, dominant troop leaders. Their power not only derives from their size but the fact that they are the protector of the group. They mediate conflicts within the group and protect the group from outside dangers such as intruding silverbacks from other groups, poachers, and other animals. The younger male blackbacks may serve as backup protection.

Although peaceful and not aggressive by nature, silverbacks will charge anything that threatens their group. Usually the charge is just a bluff; they will rarely physically attack another animal. Other intimidating behaviors include chest-beating, hooting, screaming, breaking branches, silverback with bared teethbaring teeth, standing erect on the hind legs, tearing up and throwing plants, stamping the feet, and striking the ground with their hands. These displays help prevent serious conflict not only between groups, but also among males in the same group. Silverbacks will exude a pungent odor from their sweat glands when the get excited or nervous.

When it is necessary for silverbacks to fight, it is very important for them to be able to fight well. First, they need to protect the group from predators. They also need to compete with lonemale with scratched nose males for the right to keep their group and to mate with females. Although fights usually end before anyone gets hurt, it is when these interlopers challenge a silverback for control of his group that serious violence is most likely.

When male gorillas are around 12 years old, the hair on their lower backs start to shorten and turn silver. If they are unable to take over the group from the dominant silverback, they will often leave the group and may wander alone or with other males for a few years before they are able to attract a female and form their own family. They will go out of their way to meet females, sometimes following another group for days in order to determine if the silverback is vulnerable to being overtaken, or if they can lure a mature female from the group. Frequent contact with different groups probably provides them with useful knowledge of neighboring gorillas and areas.

A group’s home range will frequently overlap with another group’s, making contact likely. Gorillas continually wander through their home ranges of 10 to 15 sq miles (25 – 40 sq. km), feeding and resting throughout the day. Competition between males over mating often influences a group’s home range as the silverback will lead them away from areas hygenia forestwith lots of strong rivals. Solitary male mountain gorillas travel further than groups which increases their chances of making contact with a variety of potential mates.

If a silverback is successful in taking over his group, or attracting a female with an infant, the new silverback will usually kill the babies that are not his. This practice of infanticide is due to the fact that females naturally only give birth every 4 years. Most cases of infanticide occur when the infant is less than 18 months old. With the death of her infant, she will stop lactating and go into estrus. This will allow him to mate, and thus be able to ensure his own bloodline at least 2 years before he would have otherwise. Females may try to thwart this by mating with more than 1 male in a multi-male group, thus creating paternity confusion. When the dominant male dies, the new leader will have mated with the mothers and treat infants in the group as his own.

About 60% of females end up emigrating to other groups, usually when they mature at around the age of 8. One reason for this is that the dominant male in a group with only one silverback almost exclusively fathers the babies in his group. If the maturing female's father is successful enough to still be the main breeder in the group, she will be forced to leave in order to avoid inbreeding. In this way genetic diversity is improved when a female joins another group. As a new member of a group, the female gets to choose whom she will mate with, but the other females of the group decide if they will allow her to stay.

Adult females in a group do not socialize with each other except for the ones that are closely related, like mothers and daughters as well as sisters. Unlike many other primates,gorillas mating it is the bond between each female and the silverback, rather than bonds between the females that keep the group cohesive. As the head female grooms the dominant silverback, she is exerting her status while teaching the others how to do it. The length of time a female spends grooming a silverback depends on when she entered the group; newcomers go last. If the leader is killed by disease, accident, fighting or poachers, the females will disperse and join other groups or look for a new protective male. Because gorillas have such strong bonds to their dominant silverback, even when groups meet and mingle, each one tends to remain with its original unit when they part ways.

Newborn gorillas are weak and tiny, usually weighing about 2 kilos, about half as much as a human newborn. For the first 4 to 5 months, their movements are awkward and they never leave the safety of their mother. With fragile hands, they are either clinging onto their mother’s belly hair and chest or held in one arm while the mother feeds. Since they don’t need to eat as much as mom with 2 day old babyadults, infants have a lot of time to play. They develop necessary physical skills by doing somersaults, climbing trees, swinging from branches, and sliding down hills.

They drink their mother’s milk exclusively for the first year. They then start to eat the plants they see their mother eating. It takes time, however, for them to learn how to eat stinging nettles and prickly thistles, which are difficult to prepare with their clumsy little hands. Although they are eating more plants, infants continue to wean until they are 3 or 4 years old. They continue to sleep with their mother in her nest until the next baby is born. Infant mortality is high; in the Virungas, 26% of infants die during their first year and 34% before they are 3 years old.

Mountain gorillas are primarily herbivores. Their diet is made up of over 100 different plants including wild celery, stinging nettles, thistles, leaves, roots, herbs, vines, and grasses. Occasionally they will eat ants, along with an odd worm or grub. They will also feed on small amounts of tree bark, wood, roots, flowers, fruit, and berries. silverback raiding crops Gorillas spend about 30 percent of each day foraging for food.

The greatest advantage to their diet is that there is a lot of it where they live and it is available year-round. Also, the plants contain a lot of water so they can go most of the year without drinking. The main disadvantage is that it is not very wholesome, so they have to eat huge amounts in order to obtain the necessary energy and nutrients. This is why they have huge bellies and look bloated. Another challenge is that plant material contains cellulose, which is hard to digest. Gorillas have a single stomach and long intestine, just like us humans. So they need to rely on microbes living in their colon to break down the cellulose and turn it into carbohydrates through a process called fermentation. Cellulose also causes flatulence, so they pass a lot of gas throughout the day.

Mountain gorillas spend a lot of their time traveling in search of food, as some plants and trees change with the seasons. Gorillas in the Virungas love to eat bamboo shoots when they are still green and tender, which are only available during the rainy season. During the dry season they enjoy the delicacy of wild black berries. Infant cuddled with momThey also like to eat the soft centers of the giant senecio trees, so they will hike up way up the mountainsides to the subalpine zone where these plants live. Because Bwindi gorillas live at lower elevations, they eat more fruit, which doesn't grow well at the higher elevations of the Virungas. Researchers surmised that, because they travel further during the fruiting season, they don't just eat it when they stumble upon it, they actively search it out.

Just like humans, gorillas are diurnal. Because they are nomadic, they usually end up in a new location each night. At dusk, they prepare nests by shoving vegetation under and around themselves. They will bend soft trees and use plants with broad leaves to provide cushioning and a blanket against the cold. Almost all of the nesting material will be made from plants the gorillas don't eat, since food plants such as thistles, time for a nap nettles, and celery aren't comfortable to rest on. The nests are arranged around the dominant silverback and are used only once. They defecate in them in the morning before moving on around dawn. But if it is cold or overcast they may lounge around for a while.

Gorillas curl up alone in their own nest, except for mothers who sleep with their infants. These mothers will find a comfortable spot where their backs will be supported as they breast feed and cuddle their babies for the night. This lasts until the infants are 3 or 4 years old, when they start to build their own nests. The fact that mountain gorillas sleep one to a nest makes it easy to estimate a local gorilla population. Researchers simply count the number of nests left by each group.

Mountain gorillas also rest in the middle of the day. This is an important time for social bonding within the group. Mutual grooming reinforces social relationships, and helps keep hair free from dirt and parasites. Mothers groom their youngsters often. Young gorillas don’t need as much rest as adults, so this is when they will play with other infants and juveniles.

Gorillas spend almost all of their time on the ground. They are mainly quadrupeds and get around by knuckle-walking. They rarely move bipedally as humans do. They can stand for short periods, usually to reach tall plants and while they beat their chests; it baby on mom's backmakes them look more menacing.

They can climb trees, but young gorillas are much more arboreal than the large adults, who usually will only do so to reach fruit in a tree. Gorillas cannot swim. Groups usually move less than one km per day. They usually only move longer distances when they have had a stressful encounter like an aggressive confrontation with a lone male.

Gorillas are generally quiet animals. But they are very social, so communication is important. Communication is used to teach the young the many skills that they need to survive, and for other gorillas to communicate about food, social relationships, distress, and mating. Gorillas communicate using visual signals (gestures, body postures, facial expressions), auditory signals (vocalizations), olfactory signals (odors), and tactile behavior (grooming).

The most well-known gorilla gesture is chest beating (actually they slap with open hands). Males do this to show stature, warn other groups or even to prevent a fight. For the silverback, chest beating is a show of power, designed to intimidate. Air sacks on both sides of the adult’s larynx amplify the sound. chest beatingBut even infants beat their chests as part of their play, mimicking their elders.

Chest beating can also be part of a display that is one of the most magnificent animals behaviors in nature. It begins with soft hoots. The silverback then puts a leaf in his mouth and rises on his hind legs, now hooting faster. He then grabs a handful of vegetation and throws it high in the air. Next he beats his massive chest with cupped hands, which is so loud it can be heard miles away. Then he runs sideways, slaps or tears at more vegetation, and finally thumps the ground with heavy palms. When he starts this display, the females and infants flee to a safe distance, much like humans do when someone in the family starts acting crazy and throwing things. It is thought that the cause of this display is the build up of tension in any exciting situation and is meant to intimidate.

Silverbacks will walk rigidly in a dominance display, mainly when a lone male is trying to lure a female away from the group. They have their arms bowed and hair bristled so that they look bigger. They take short steps, have their side facing the intruder, and only look at him with a few glances.

Males also lunge or charge, whether at an outsider or at someone within the group itself. It is sometimes accompanied with a terrifying scream. Most of these actions are just meant to serve as warnings, to ward off danger or to prevent a fight. Gorillas crouch low and approach from the side when they are being submissive and approach directly when confident.

Facial infant with protruding tongueexpressions are also used for communication. For example, an open mouth with both upper and lower teeth showing means aggression. A closed mouth with clenched teeth and head jerks signal anger. They tuck their lips when they are tense. Gorillas are angry or annoyed when they stare at another, with eyebrows lowered and head angled down. If the stare is accompanied by bared gums and teeth and lips curled back, it is meant to threaten potential predators. It is often combined with a mock charge, screams, and roars. Infants will pout when their mother leaves them or they don't get what they want. Their lips are pursed and slightly parted and their eyebrows are raised in this distress signal. Gorillas are afraid when their mouth is an angry femalewide open, the eyebrows are raised, their eyes move back-and-forth, and their head is tilted back.

Males emit a strong, pungent odor from glands under the armpits. They do this when excited or faced with an aggressive threat.

Gorillas groom each other to remove parasites from each other's hair and to increase social bonds within the group. Females will groom the silverback and their youngsters, but not each having a bad hair dayother unless they are closely related. Immature gorillas will also groom each other. Grooming is almost always initiated by the mother and protested and finally stopped by the infant, just like people!

Please be patient- we are awaiting audio files for the vocalizations listed below.

Because mountain gorillas live in dense vegetation where it is difficult to see each other, the main form of communication is through vocalizations. There are about 25 distinct vocalizations and each has its own meaning. Grunts and barks are heard most frequently while traveling, and tell the gorillas the whereabouts of other group members. They are also used to scold or discipline youngsters. Silverbacks will hoot loudly when they see another group and it is a warning to keep their distance. Other gorillas will hoot when they have been separated from their group. Screams are loud and can be repeated many times, especially by gorillas who are upset or fighting. Roars are given by adult males and signal alarm or warning. The group usually hides behind the silverback when hearing this. Deep rumbles, belches, and grunting communicate contentment and are heard frequently when they are feeding and resting. Pig grunts are a series of short guttural noises and signal that the gorilla is annoyed with another gorilla in his group. Young gorillas will hoot, holler, scream, and chuckle when they are playing and cry when they are distressed.

Gorillas and humans evolved from a common ancestor, share 98.4% of each other’s DNA, and like human beings, are intelligent, playful, emotional, and family-oriented. Different gorillas exhibit different personalities, just like humans. Some move differently than others, some are more curious than others. Some are confident; some are shy. Some are nervous; some are calm. Some even seem to have a sense of humor!

Gorillas have emotions and feelings similar to humans. They can be curious, bored, annoyed, excited, afraid, and worried. They can have pleasure, get excited, be afraid, show affection, be thoughtful, and be hostile. Dian Fossey observed a brother and sister, ages 3 and 7, sulking off with lower lips hanging down when a mother denied their attempts to cuddle and groom her infant. She also saw the entire group huddle around their now dead silverback, apparently in mourning.

Mountain and lowland gorillas are thought to have similar intelligence. Mountain gorillas have not been observed using tools, so they are thought to be less intelligent than chimpanzees, who use them frequently. This may not be a good indicator of intelligence however. Gorillas may not need to use tools because their food is so abundant and easy for them to get to. For example, chimpanzees have been observed fishing for termites with sticks, whereas gorillas will simply smash the mound to get to the termites. They are so strong that, for them, it is a more efficient method.

Lowland gorillas have only recently been seen using tools. An adult female gorilla was observed using a branch as a walking stick to test water deepness and to aid in her attempt to cross a pool of water in a swampy forest clearing in northern Congo. Another researcher saw a different adult female using a detached trunk from a small shrub to dig for herbs. She then used the trunk as a self-made bridge to cross a deep patch of swamp. In contrast to chimpanzees using tools use to obtain food, it appears that gorillas use them to navigate their habitat, which is a more challenging task for them.

Perhaps the best indicator of Gorillas’ intelligence is the world famous Koko, a female lowland gorilla born in captivity in 1971 and taught American Sign Language since she was 1 year old. Koko has a working vocabulary of over 1000 signs and understands approximately 2,000 words of spoken English. Koko initiates the majority of conversations with her human companions and typically constructs statements averaging three to six words. Koko has a tested IQ of between 70 and 95 on a human scale, where 100 is considered "normal”.

This photo was actually taken by Koko in 1978 (when she was just 7 years old), and the photo she's snapping is of herself aiming the camera at the mirror. This photo alone dispelled two major misconceptions about gorillas: 1) that they were incapable of using tools, and 2) that they were not capable of recognizing themselves in a mirror — a cognitive ability that is supposed to be necessary for self-awareness. Since then, Koko has gone on to dispel many other myths about gorillas (and other great apes) such as showing how gentle they can be with humans and even tiny kittens, that they are capable of the full range of human emotions, that they can empathize with others, have a sense of humor, can be embarrassed, and that they can feel and express both physical and emotional pain (e.g., grieving for her kitten) and deep love and a sense of kinship across species (e.g., with Dr. Penny Patterson). Moreover, they are highly intelligent and can use technology (e.g., VCRs, remote controls, computers, phones) — and even language (sign language in Koko's case) — in both conventional and innovative ways.

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an angry female
This female is saying "Stay away from me and my baby!"
Photo courtesy of www.hoothollow.com
intimidate v. To frighten or overwhelm someone,
especially in order to make them to do something.
silverback with bared teeth
Even though these displays are usually a bluff, they are ferocious enough to
intimidate any creature in the forest except for another strong silverback.
Photo courtesy of www.hoothollow.com
infants playing
Infants love to chase, tackle, and wrestle with each other. This play creates close
bonds and helps them build social skills they will need later in life.
Photo courtesy of www.hoothollow.com
chest beating
When a silverback beats his chest, he is basically saying, "I'm big, I'm bad,
and you'd better steer clear of me if you know what's good for you. I'd
rather not hurt you, so I'm sending you this message so you'll leave and we
can avoid a fight." Photo courtesy of www.hoothollow.com
n. Sounds or words coming from the vocal cords
that are meant to communicate something.
adj. Ready to conform to the authority
or will of others. Obedient.
n. One who comes without
permission or being invited.
v. To stand stiffly like the bristles of a wire brush.
v. To copy or imitate closely, especially in
speech, expression, and gesture.
n. The muscular section of the throat that
contains the vocal cords.
n. The natural height of a human or animal in an
upright position. An achieved level; status.
n. An organism that grows, feeds, and is sheltered
on or in a different organism while contributing
nothing to the survival of its host.
v. To infer something without sufficiently
conclusive evidence.To make a guess.
giant secdio trees
These trees grow to 6 meters (20 ft.) tall and are found just below the tree line in afromontane forests in eastern
Africa (shown here on Mt. Kilimanjaro). They are an important source for traditional medicine and are used to treat
pulmonary complaints, head colds, and liver conditions. Mountain gorillas will tear these down to eat small amounts
of the core. Researchers have theorized that because the gorillas expend so much energy going up the mountains
for such small quantities of food, that they must be medicinal for them. Given the fact that they live in an oxygen
deprived environment and that they are very active animals, it may be for the pulmonary benefits they get from the
trees. Photo courtesy of blhphotography via CC BY 2.0
mt lassen
The term subalpine refers to the zone immediately below tree line around the world. Species that occur in this zone
depend on the location of the zone on the Earth. The tree line is the edge of the habitat at which trees are capable
of growing. Beyond the tree line, they are unable to grow because it is either too cold, not enough air pressure, or
not enough moisture. This is Mt. Lassen in California. You can clearly see the tree line.
Photo courtesy of Brian M. McDaniel via CC BY-SA 3.0
n. Something pleasing and appealing,
especially a choice food.
bamboo shoot
n. The young shoot of the bamboo plant that is
sliced, cooked, and eaten by people, especially in
East Asian cuisine. Photo courtesy of Joel Abroad
via CC BY-NC-SA 2.0
n. The presence of excessive gas in the
digestive tract. Self-importance.
n. A group of chemical reactions that
split complex organic compounds into
relatively simple substances.
n. Organic compounds that include sugars and starches
and serve as a major energy source in the diet of animals.
n. A complex carbohydrate that is
composed of glucose and is the
main part of the cell wall in most plants.
adj. Swollen beyond normal size
by fluid or gaseous material.
n. A nourishing ingredient in a food source.
v. To look for or search for
food or provisions.
n. An animal that feeds chiefly on plants.
n. The number of deaths of infants per 1000 live births.
v. To drive off or scatter in different directions.
n. Position relative to that of others; standing.
v. To put to use, put forth, or bring to bear,
sometimes with strenuous effort.
adj. United or stuck together.
n. The breeding of related individuals within an
isolated or a closed group of animals or people.
n. An animal who produces offspring.
A person who breeds animals or plants.
v. To leave one country or region to settle
in another. The opposite of immigrate.
n. The state of being a father; fatherhood.
v. To prevent the occurrence or attainment of.
To stop something from happening.
n. Direct line of descent; pedigree
n. The periodic state of sexual excitement in the
female of most mammals, excluding humans.
It precedes ovulation and is when the female is
most receptive to mating; going into heat.
v. To produce milk.
n. The act of killing an infant. The
practice of killing newborn infants.
v. To tempt or attract with the promise
of pleasure or reward.
n. One that interferes with the affairs
of others, often for selfish reasons.
adj. Having a penetrating, biting, or caustic
taste or smell.
v. To ooze forth.To discharge or emit.
adj. Rough, violent, loud, noisy, and
lacking in restraint or discipline.
this gorilla is tense
Photo courtesy of smithpal via CC BY-NC-ND 2.0
gorilla with mouth pucked and open
Photo courtesy of smithpal via CC BY-NC-ND 2.0
infant with protruding tongue
Gorillas will protrude their tongue when they are uncertain or when they are concentrating.
Photo courtesy of the Gorilla Doctors
juvenile grooming another
v. To tend to appearance. To make neat and tidy. Photo courtesy of Joachim Huber via CC BY-SA 2.0
having a bad hair day
Like humans, gorilla mothers vary in the caretaking of their infants. Some will be extremely
attentive, while others are somewhat indifferent to the handling and grooming of their
offspring. Photo courtesy of Seth Lieberman via CC BY-ND 2.0
silverback with a big belly
A full-grown mountain gorilla like this silverback can eat up to 60 pounds of vegetation a day!
Photo courtesy of Sigrist Adventures
knuckle-walking juvenile
Using both arms and legs, they put their weight on the knuckles while the fingers are rolled up into the hands.
Photo courtesy of Sigrist Adventures
baby on mom's back
Mothers carry their infants ventrally (on the belly) for the first few months. Later on in their first year,
when they have a stronger grip, do they start to ride dorsally (piggyback style).
Photo courtesy of Wofgang Moeller
juvenile in the trees
adj. Relating to trees. Animals that live in trees.
Photo courtesy of Paul Sodemann
adv. To move around on the legs only.
getting around on all fours
n. A four-footed animal. Photo courtesy of James Parker
infants playing at naptime
Play helps young gorillas learn how to communicate and behave within the group. Photo courtesy of Joachim Huber
via CC BY-SA 2.0
2 juveniles take a nap together
It takes time for a gorilla to learn how to build a good nest. By the time they are 2 years old, infants
will start clumsily throwing together a few leaves. They then build small nests that are connected to
their mother's before being able to construct an independent nest with sufficient padding and a
proper rim. Photo courtesy of gorillacd.org
time for a nap
During the rainy season they like to build their nests in the hollows of tree trunks. This not only offers
protection but provides early morning snacks of decayed tree bark and roots. Notice the mother's hand around
the infant. Photo courtesy of Stefan Gara via CC BY-NC-ND 2.0
adj. People or animals who have no fixed
home and move from place to place in
search of food and water.
adj. Active during the daytime rather than at night.
eating wadded up vines
Gorillas will rip out a 2 meter (6 feet) long gallium vine and carefully wad it up before putting it in their
mouth. Notice the injuries to the fingers and knuckles, which probably affects this gorilla's ability to
walk normally. Photo courtesy of smithpal via CC BY-NC-ND 2.0
juvenile chewing tree bark
Sometimes gorillas fight over small patches of food. For example, in Bwindi, gorillas have been observed
clustering around dead trees and nibbling on chunks of rotten wood. It was discovered that these trees
contained unusually high concentrations of sodium and that this was the source of over 90% of their
dietary sodium. Photo courtesy of Paul Sodemann
female eating wildcelery
They are quite particular about what parts of some plants they like to eat, and some take a lot of
preparation. This female is carefully stripping the stalk from the heart of some wild celery.
Photo courtesy of smithpal via CC BY-NC-ND 2.0
Infant cuddled with mom
An infant get his first bits of food from remnants of leaves or bark that has dropped from his mother's
mouth and into her lap. He just has to pick it out of her belly hair and put it in his mouth. Adults and
youngsters will occasionally eat their own feces, probably for the minerals it contains.
Photo courtesy of gorillacd.org
silverback raiding crops
Gorillas that live near people sometimes raid farms, eating and trampling crops. This silverback is eating
a farmer's maize. Photo courtesy of gorillacd.org
n. Microscopic bacteria that cause
disease or fermentation.
mom with 3 day old baby
A mother and her 3 day old baby rest in the midday sun. Most gorilla births take place at night. This is when
the animals are stationary and other members of the group are unlikely to interfere with the birthing process.
Photo courtesy of Wolfgang Moeller
infant eating a stem
At 7 months of age when infants are still suckling, they start to pick up pieces of vegetation to eat but
haven't yet perfected the skills of stripping leaves from stems or wadding vines to stick in their mouth.
Photo courtesy of gorillacd.org
baby next to mom's breast
Weaning is the process of switching a young mammal from mother's milk to other food. During the first
year, infants show no preference on which breast they will nurse. As they get older, for some reason
they prefer the left breast twice as much as the right. Photo courtesy of Joachim Huber via CC BY-SA 2.0
infant held in mom's arm
The group as a whole takes responsibility in supervising infants, especially in dangerous situations. Juveniles
are known to pick up and carry an infant when the mother is incapacitated or there is an emergency and the
group has to flee the scene. Photo courtesy of smithpal via CC BY-NC-ND 2.0
Between 4 and 5 lbs
When males intervene between 2 quarreling females, they do so neutrally. They usually don't favor
either female, they just try to stop the conflict. When they do give obvious support, it is to help the
victims or the targets of the attacks. Because the silverbacks are so much stronger than the females,
ths is almost always successful. By doing this, he prevents the stonger females from consistently
dominating the weaker ones. Photo courtesy of the Gorilla Doctors
mom with 2 day old baby
The skin color of a newborn is usually pinkish gray with some pink spots on the ears, palms, or soles. The
head hair is short and slick and ears are prominent. The face is wrinkled with a protruding nose that
resembles a pig's snout. They spend most of the day nursing and sleeping. Photo courtesy of gorillacd.org
baby breast feeding
Newborns rarely suckle for more than 1 minute at a time. While a mother is nursing, her dung often has a
white covering due to the habit of eating the infant's feces during its first 4 or 5 months of life.
Photo courtesy of gorillacd.org
gorillas mating
Male gorillas sometimes use mate-guarding to persuade females to mate. They will follow them
persistently and vocalize a "neighing" sound if she moves away. But it is the female who initiates
over 63% of copulations in most groups. The act itself lasts only a few seconds and is achieved with
an approx. 4 cm (1.5 inch) long penis. Photo courtesy of smithpal via CC BY-NC-ND 2.0
silverback with open mouth
Due to the intense competition between males for access to females, few males breed before they reach 15
years old. Male gorillas typically father 10-20 offspring, often with 3-5 different females. There are groups,
however, that have more than one male that mates with females in the group. Photo courtesy of
Albert Herbigneaux
hygenia forest
Gorillas will expand their range to seek out seasonal plants or when food is scarce. In the Virungas, their
primary habitat is the Hagenia forest because most of the foods they eat are found there year-round.
Because fresh bamboo shoots are only available to eat during the rainy season, the bamboo forest is a
secondary habitat for the gorillas. Photo by Tony Hartman
n. The geographic area to which an
animal normally confines its activity.
male with scratched nose
Bloody battles sometimes occur between silverbacks when they square off.
Usually the wounds are not serious and heal quickly. But there are times when
the injuries lead to death. Canines can cause deep, gaping wounds and may
even break off and get stuck in the skull of their opponent.
Photo courtesy of Joachim Huber via CC BY-SA 2.0
Silverbacks are the emotional center of the group. They get lots of attention during
rest periods, with most of the other gorillas lying around them. They are really
protective of mothers with new infants and are very patient with playful infants. They
will even care for orphaned young gorillas. For example, if a mother dies or leaves the
group, the silverback is usually the one who looks after his abandoned offspring. They
will even allow them to sleep in his nest, but they won’t carry the little gorillas- they
do have their limits! Photo courtesy of James Parker
baby laughing at naptime
Infants don't need to rest as much as the adults. So while the others are napping, they will climb trees,
wrestle, chase each other and do somersaults. They even harass the adults, who are trying to rest. The
silverback and his females are very patient and tolerate this behavior and even enjoy playing with them from
time to time. Photo courtesy of Joachim Huber via CC BY-SA 2.0
gorilla infant
The infant stage lasts from birth until they are about 3 years old. Gorilla babies develop phsyically much
faster than human babies. By their second month they have already begun crawling, whereas humans
start around their seventh month. After 5 or 6 months, they are beginning to stand and walk. Humans
don't start to walk until they are 10-12 months old. Photo courtesy of Lukas Vermeer via CC BY-NC-SA 2.0
juvenile gorilla
Gorillas are considered juveniles between the ages of 3 and 6. They start to become relatively
independent when they are 3-4 years old and begin to build their own nests next to their mothers.
It is hard to distinguish between males and females during this period. Photo courtesy of gorillacd.org
mom and baby in the rain
Female gorillas are fully mature and able to reproduce at about 10 years old. They usually have a single baby (and
rarely twins) every 4 years and usually produce 3-5 babies in their lifetime. The gestation period lasts 8.5 months.
Females are able to conceive for only 1 or 2 days each month. Photo courtesy of smithpal via CC BY-NC-ND 2.0
Males between 8 and 12 years old are called blackbacks. This is the stage that resembles adolescence in humans.
Blackbacks slowly develop the distinctive characteristics of adult males. By the time they are 12 or 13 the hair on their
backs will shorten and start to turn gray. They may remain with the group if they don't challenge the dominant silverback.
Photo courtesy of gorillacd.org
Silverbacks take responsibility for the safety and well being of the group. They decide when and where the group goes.
When they move, everyone moves. When they stop to rest, everyone stops. They lead the group to feeding sites and
away from danger. By age 12 or 13, males can be considered silverbacks, but most will not reach their full adult size until
the age of 15 or 16. Photo courtesy of Ferran Lloret
gorilla family
The largest known family is the Susa group in Rwanda. It has 38 members including 4 silverbacks, 13 babies, and the
only known surviving mountain gorilla twins. Photo courtesy of mrflip via CC BY-SA 2.0