Chimpanzees live in one big area known as a ‘home range’. This is generally ten thousand to twenty thousand acres, but may be a great deal smaller. It may overlap another chimp group’s home range. Chimps never leave their home range, though some might form a temporary group of ten or twenty, and go off by themselves away from the others. Chimpanzee groups may have as few as forty or as many as two hundred chimps.
Chimpanzee infants are very reliant on their mothers, but by 3 years of age, they are ready to go exploring beyond their mother’s lap.
Chimpanzees aging from 5 to 7 years old are called juveniles. They are very energetic and enjoy wrestling, swinging on branches, playing by themselves or with other juveniles, eating, watching (and sometimes messing with) the adult chimps. The males also enjoy practicing their charging displays.
Adult chimpanzee males are very tolerant to an infant or young juvenile, until they reach 6 years of age. They fight for their place as dominant male (the male in charge of the group) and, for a long period of time, will fight off anyone who tries to beat them. When the time comes for a female to be mated, the dominant male will fight off everyone else who tries to mate with her. The dominant male usually mates with all the females in the group. Only on occasion will any subordinate male (lower ranking male) be able to mate with a female. Males are much less dependent on their mothers than adult females, although Jane Goodall once said that after a fight over dominant male, a chimpanzee ran to his mother for protection and comfort.
Adult chimpanzee females will often play with their younger siblings. They have their first baby at 12 or 13 years of age. Until that time, they stay close to their mothers. The females also help take care of others babies. Jane Goodall recalls an adult female, Gilka. Gilka had no babies of her own, so she began to take care of orphaned baby chimps. Eventually she was ‘adopted’ by four orphaned chimpanzees. Jane often referred to her as ‘Aunt Gilka’.
Every member of a chimp society has its own distinct rank or status, depending on its age and sex. The big, powerful males have high status, while smaller females rank lower. If a male is walking along a branch where a female is sitting, she will get up and let him pass.
Rank does not depend on size and strength alone; for instance, infants and young juveniles rank highest of all; they are protected by their mothers and treated kindly by everyone. But, as their tail tuft disappears, they lose their privileged status and may be threatened or even attacked if they approach an adult. They eventually learn the rules of the chimpanzee society: to keep away from adults, particularly when they are feeding, to get out of the way when an adult male is charging, and to make the correct submissive gestures towards an aggressive adult.
A normal day in the chimp society starts at daybreak when they wake. The first activity is looking for breakfast. When a band of chimpanzees find a tree with plenty of fruit, they become very excited and bark loudly. This alerts other small bands of chimps, which make their way to the spot. After the excitement of meeting each other is over, they settle down to eat. Later, after each chimpanzee has eaten its fill, they sit around throughout the hottest hours. During this time, the juveniles will usually play together, while the infants will watch with great interest. After a while though, they will get tired and sleep. The adults will groom each other or sleep, and the females will also nurse their babies. Adolescent males enjoy practicing their charging displays, while adolescent females prefer grooming sessions. They get going again in the late afternoon. When chimpanzees sleep during the afternoon, they build nests in the ground by piling up a bunch of grass and leaves in a circle.
Chimpanzees like to groom each other. This not only helps to clean the chimps, but also creates friendships. It is said that chimpanzees find termites in the hair of other chimps and eat them. This however is not true. The contents of most chimpanzees’ hair consist of dirt, dust and ticks, and these are generally dropped on the ground.
When a chimpanzee wants to be groomed, it will sit in front of another chimp and point to the spot where it wishes to be groomed. While grooming, chimpanzees will often make clucking noises, or soft hoots.
When chimpanzees greet they will hug, kiss, pat each other, and touch. This is also used for comforting a chimpanzee after a fight.
When greeting a dominant chimpanzee, a subordinate will approach him with the correct submissive postures: holding out a hand, or, crouching and presenting the rump.
Juvenile chimpanzees and young baboons often play together on meeting. This may be surprising for chimpanzees will occasionally feast on infant baboons.
Chimps eat fruit, vegetables, leaves, eggs, buds, nuts, honey, and a variety of meat including colobus monkeys, bush pigs, infant chimpanzees, and termites.
Chimpanzees use tools for food gathering e.g., ‘fishing’ for termites with a stick, and drinking water using leaves. To fish for termites the chimpanzee needs a thin stick. It takes the stick and rips off the leaves and twigs. It then pushes the stick down the termite mound. It twists the stick a little, and then pulls it out. The termites will cling to the stick, and the chimpanzee will use its mouth as a vacuum and suck them off. If the stick gets bent, the chimpanzee will simply break of that part of the stick and use the remaining piece. This fishing for termites is not an instinct. In fact, the first chimpanzees sighted doing this were the Gombe chimps. They have also been the only chimps that have done that other than captive chimpanzees, and that is only because of human teaching. Scientists have also discovered that chimps use medicinal plants to care for themselves for illnesses and injuries.
To drink water, a chimp will get a leaf, chew it to a pulp, and dip it in the water. The water soaks into the leaf, and the chimp will put the leaf into its mouth, and suck on it.
Each evening just before sunset, chimpanzees build nests in trees to sleep in. Nests are built in trees during the night. They find tall trees, to keep themselves safe from leopards. Mothers and infants are usually found in the highest trees, because an infant chimp is more likely to be a leopard’s target than a bigger chimpanzee.
Making a nest is very simple and consists of 4 steps. They are as follows:
1. Find a tall tree (15-100 ft.) with a fork in it.
2. Bend and intertwine leafy branches to make a soft, springy platform.
3. Cover the inside with leaves.
4. Make some minor adjustments, e.g. break off or bend any uncomfortable twigs, bunch up leaves under the head to make a pillow
Occasionally, they will come back to a nest that was built a while ago, but usually build a new one every night. A young chimpanzee (newborn to 3 or 4 years old) will sleep in its mother’s nest. From 3-4 years of age, a chimp will start trying to make its own nest, but never make one to sleep in until about 5 or 6 years of age.
Nests aren’t roofed for protection against water, so when it rains during the night, the chimpanzee will simply hunch its body and let rain fall off its back. The mothers shelter their infants from getting wet. Chimpanzees never shelter from the rain; they just sit in the open and look miserable, occasionally shaking themselves to throw off the raindrops clinging to their coats.
Jane Goodall has seen male chimpanzees perform what she calls, a ‘rain dance’, during harsh rains. She gives an example of one in her book, My Friends The Wild Chimpanzees,
“Hooting apes stage frenzied rain dances when pelted by a downpour. In this sequence, a chimpanzee first crouches, then stands erect and plunges down a slope, yelling all the while. Grabbing a branch, he slaps the ground as he charges toward a tree, and climbs the trunk. Hurling himself downward, he snaps off a bough and drags it behind him. To break his headlong rush he swings around a tree. Finally, he plods uphill to turn and charge again. Mothers and their young watch from the ridge.”
How Chimpanzees Communicate
Chimpanzees have very expressive faces. They communicate with a number of facial expressions, gestures and calls. A few of the more common expressions are as follows:
The Play face
This is a relaxed face, often with the mouth open and the top lip covering the teeth. It is used when playing happily.
The Pout face
This face is made with the lips pushed forward. It is used for greeting or begging from another chimpanzee. It is also seen in all infants, juveniles and female adolescent chimps when they cannot see their mothers.
The Grin face
· Open Grin
This is made with the mouth open and both top and bottom teeth showing. It can express fear, excitement or a tantrum.
· Fear Grin
This is made with the top lip curled in and teeth showing. It is used when a chimp is frightened or unsure, such as when approaching a higher ranking chimp.
Chimpanzees also communicate through a number of calls. A few of them are listed here:
This is a long drawn out ‘wraa’.
This call is a quiet ‘huu’.
This is a soft bark.
This is a mixture between a pant and a grunt, which is called pant-grunt.
Males perform what is known as a threat display, when fighting for dominant male. Whoever has the most impressive and scary display, is usually the dominant male. A chimpanzee’s threat display consists of five steps. They are as follows:
1. Throwing stones, sticks, branches, anything in their way (including infant chimps).
2. Standing up, hair bristling and doing everything else to make themselves look big.
3. Screaming and yelling at the top of their lungs.
4. Charging towards the person or thing.
5. Attacking the person or thing offending them.
Chimps do not like loud noises. Jane Goodall has said that a chimp named Mike, who was the lowest ranking male in the group, once found some old tin cans lying around in her camp. He messed with them, and discovered they made noise. He then charged and rolled them around, making a loud, scary noise. The other chimps heard them and ran. Thus Mike was the dominant male, but only for a short time, as another chimpanzee soon overpowered him.