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Biology of the common chimpanzee
The common chimpanzee is a great monkey species living in tropical africa, omnivorous with frugivorous predominance, largely arboricolous and diurnal.
ø The great monkey is genetically nearest to the man with more than 98 % of the genetic inheritance common to both species.
With the gorillas, the chimpanzees are the only representatives of the great monkeys on the African continent. They are classified in the order of the primates, family of and Pan gene. We distinguishe two species from them:
    · the common chimpanzee (Pan troglodytes), main species of the H.E.L.P. project
    · the pygmé chimpanzee or bonobo (Pan paniscus), this last livee only in the democratic Republic of Congo, ex Zaire.
Among the common chimpanzees, we can distinguish four subspecies, and this, due mainly to their geographical separation: Pyear T troglodytes which is in central Africa and in particular in the Republic of Congo, Pan T schweinfurthi in East Africa, Pan T verus in West Africa and Pan T vellerosus or chimpanzee of Nigeria-Cameuroun

ø the body of the chimpanzee is adapted perfectly to climb and balanced itself to trees. The chimpanzees have long disproportionate arms (in comparison with the mankind) facilitating the access to the branches. They have hands and feet very flexible and prehensible, enabling them to catch up itself easily. Thanks to their skill, they can pass from branch to branch without those breaking under their weight. The fingers are reduced, curved and have nails. Hands and feet are prehensible.
Like the mankind, they do not have a tail and hairs on the face, the plant of the feet, and the palm of the hands. The common chimpanzees have powerful molars and the males also have large canines. Upright, the males can reach from 1 to 1 meter 70, the females being smaller.
ø TheurJeanette in 2004 peeling is in theory black, rather sparse, but longor, color and distribution on the body vary with the age, the subspecies and the individual. The young individuals have the black hairs, the face rosâtre and a toupillon of white hairs at the back, which disappears as the end of their first years. With the age, the face gets more obscure, the color of the hairs can be cleared up,the hairs become rarer on the face and the head.
Some differences are to be noted according to the subspecies considered. For example:
      · The Eastern common chimpanzee (Side T schweinfurthi) has a longer peeling than its subspecies and the color of the face goes from bronze to coppered. Its weight can reach 43 kg for the males and 33 kg for the females.
      · The common chimpanzee of central Africa (Side T troglodytes) raises a black facial pigmentation, especially with the age. Its weight can reach 60 kg for the males and 47 kg for the females. It is the most massive subspecies.
      · As for the Western common chimpanzee (Side T verus), it has a rather pink color of skin which becomes darker with the age. Peeling is black but can go from brown to hazel nut.

Distribution and habitat
ø Distribution, covering 21 country :
    · The Eastern common chimpanzee : Democratic republic of Congo, Uganda, Tanzania, Burundi, Rwanda, Sudan and Central African Republic (RCA);
    · The common chimpanzee of central Africa : Cameroun, Gabon, Republic of Congo, equatorial Guinea, RCA and Angola;
    · The Western common chimpanzee : Guinea, Côte.d'ivoire, Mali, Liberia, Guinea-Bissau, Sierra Leone, Senegal and Ghana ;
    · The fourth subspecies is in Nigeria and Cameroun.
ø the habitat varies to wet dense forests, where live the densest populations, to the dry forests and raised savannas, while passing by the marshy forests or of mountain (up to 2800 m of altitude).

Locomotion Example of a mother chimpanzee walking on his feet to cross a water zone
ø the chimpanzees move on the ground in a quadruped way, in a their very own position (like with the gorillas) which is called "knuckle-walking". It is a type of quadruped walk based on the fact that the weight of the higher part of the body is supported by the dorsal surface of the second phalanges of the fingers of the hand. In the trees, this species can also move in a quadruped manner.
ø On the ground, the chimpanzees can adopt a biped walk. But that comes mainly during the demonstrations of predominance, the displays or to cross on the ground some obstacles like mud or water zones, not very wide.
ø the chimpanzees cannot swim and certain populations are afraid of water, especially if this element is not very present in their environment.

Ecology and food behavior
ø Mékoutou, eating ants tisserandesIn general, the chimpanzees pass almost half of their time feeding themselves (on average 47 %) and a good part of the time remaining (13 %) is dedicated to move from a fedding place to another. Most of the time passed to feed themselves takes place mainly in height, in the trees, and this up to 88 % in rain season. There are two peaks of food spread out over one day: one in the morning between 7h and 9h and one in the afternoon between 15h30 and nightfall.
ø Food diversity with the chimpanzees is remarkable; they consume seeds, nut, fruits, flowers, sheets, stems, sap, bark, honey, insects (ants, termites), as well as the vertebrate ones (in particular monkeys). The common chimpanzee can introduce 300 different species of plants in one year and approximately 20 different species per day.
ø Jeannette consuming the base of a base of morantacée, kind of a large herbacéIt was shown that the participation of the fruits in their food represents approximately 48 %. The share of the sheets and buds represents 25 %. The 27 % remaining include a mixture of seeds, flowers, stems, sap, etc... During the dry season, when the fruits become rare,  food like the flowers, the barks, the stems become important food resources.
ø The chimpanzees can enrich their food with stone, soil and clay ingestion found on the level of ant-hill, and this for a mineral contribution. It was observed that it is on the one hand the very fine consistency of material and, on the other hand the richness of this one out of sodium chloride which encourage the animals to introduce the "saltworks" created by the termites themselves.
ø The observation of
coprophage behavior in the chimpanzees raises various questions among the scientists. For some, it acts of a mental or nutritional imbalance, related to food deficits, fibres in insufficient quantity in the ration, the bordom or the stress. It is increasingly allowed that the coprophagie can also be a physiological adaptation allowing the maintenance in the digestive tract of ciliés which digest cellulose or the assimilation of vitamins synthesized in the large intestine but assimilable in the small intestine.
ø The chimpanzees are omnivores able to hunt. In general, the males form hunting groups. They can hunt wild pigs, antelopes (in general new born ones) and especially monkeys. A species of monkey very often hunted is Procolobus badius. The behavior of hunting shows strong variations according to the populations of chimpanzees, some of them using this technique very often. The hunting act can be divided into three phases:
    · the chase which in general lasts only a few seconds or minutes and covers a short distance;
    · the capture which is a short event ending in the beginning of the dismemberment of the prey;
    · the consumption which is often accompanied by important social exchanges: the individual having carried out successfully slaughter, will eat the greatest part of the prey; the others will beg the remainders which they will obtain in general. Very often, the meat consumption is associated with sheets.
Choupette using a stick to break palm nuts ø Another technique of food is to be noted: the use of tools. Various examples of use of tools by the chimpanzees were observed on several occasions, that is to extract living insects from tree trunks or to open nuts.
The Western common chimpanzee uses stones as hammer to break Palm nuts. First of all they select a stonel then place the nut on another stone or in the hollow of a large root of tree, this in order to immobilize it; finally they hit the nut with the stone in order to break it. The individuals can use the same stone in a repeated way. The nut species for which they use these tools are Coula edulis and Panda oleosa. The subspecies of central Africa, as for it, uses kinds of bludgeons out of wooden instead of stone as a hammer. The subspecies of the East seeks the same nut species but does not break them with tools, they feed themselves  rather with the skin being on the surface. That suggests a certain degree of differentiation among the subspecies, kind of regional culture.
About the termites "fishing" , for example, the chimpanzees of central Africa select brushwood which they insert inside the nest (in the shape of small cliff); the termites, attacking any foreign body entering the nest, position themselves on this same brushwood that the chimpanzee will extract and will lick thereafter. The chimpanzees of the East adopt the same behavior but "to fish" ants; there are thus local variations regarding the "fished" species.
Within a group, the youthful ones learn how to use the various tools by observing their parents and while trying to imitate their mothers and elder.
Some chimpanzees were observed eating in certain cases plants known for their therapeutic vertue. Are they good pharmacists and heal themselves this way?

Social structure and behaviors
ø The social structure for the common chimpanzee is described as a society known as  "Fusion-Fission". At the base, there is a community, made up of sub-groups varying in a number and composition, being linked "fusion" or separating "fission", under the influence of various factors. A community includes all the individuals who are regularly observed within the various temporary sub-groups and this, over several months. This community can be described as a "unit group" and its members share a common space of life, the surface of distribution. The number of individuals within a community can vary from 20 to approximately 80.
Females group with their babieslLiving in groups can bring three advantages:
    · to decrease the pressure of predation
    · to improve the exploitation and protection of the food resources
    · to make easier a social or co-operative behavior, like the reproduction or hunting.
Within a community of chimpanzees, we can meet groups of different nature :
    · only males
    · adult females accompanied by their small bisexual babies
    · a female and its descent
    · an individual alone
In general, the average size of each sub-group is lower than 10 and borders five individuals rather. There is a great diversity in the constitution of these sub-groups or groups. This great fluidity makes it possible to each individual to have the advisability of joining to sub-groups of different sizes. This diversity is observed for all the activities, whatever the nature and the size of the group is.
It was observed that three principal factors intervene in the variations of the size of the sub-groups:
    · first of all the availability of fruits which increases in rain season, which explains more important sub-groups
    · sexual interactions: the females in oestrus tend to come to inflate the number of individuals within the groups
    · the period of hunting (mainly in rain season) can also help to explain the important size of the groups during this season
The different communities have vital fields which can overlap. Sometimes fights very violent can take place between males of close communities, even often until causing very serious wounds or causing the death of interacteurs. Indeed, the males represent the "core" of a community and protect the members of their group. They spend their time supervising, they patrol around the limits of their territory by excluding any nonrelated candidate to the group.
Fights from predominance can occur between males of the same community because this one is based on a system of hierarchy. The males are phylopatric, i.e. that they tend to remain in the community where they were born. The more the males of the same community get older, the more they join the other males and are integrated into the hierarchy. Associations between males are strongest within the group and we often attends with divisions of food or scenes of grooming between them. Within this structure, the status "alpha", i.e. the status of the male having the highest placed in the hierarchy, is often obtained thanks to a whole of coalitions established with a brother or a nonrelated older male.
Contrary to the males, the females rather tend to move away from their habitat of birth, especially after having reached maturity. Moreover, the nonrelated females but pertaining to the same group, will not show many interactions between them.
Child murder was also observed for this species and occurs when an adult male keep silent the child of a not very familiar female or when a doubt about the paternity of the child remains.

Ecology and space of life
ø Like many mammals, the chimpanzees are sedentary and concentrate their activity on a limited surface, corresponding to their vital field. This last is on average about 7 km² in this species; the average daily distance traversed during displacements (most important being done on the ground) is estimated at 3,90 km. In addition, it was often observed that the males use a surface much larger than the females (1,5 to 2 times larger at Kibale).
By analyzing the vital fields of the chimpanzees of Gombe (Tanzania), it was shown that the individuals tended to occupy inside the vital field of the community some zones more than others: we speak about "center surfaces". The localization of these "center surfaces" remain stable over a period of at least one year, but it appears that the size of those varies in a seasonal way for the males. Moreover, the males are much more often observed in limits of surfaces that the females. The females in heat, as for them, see their space life increasing and use a surface more important than the normal in order to meet males of their own community or even of close communities.

ø The way of communication between individuals, sub-groups or even different communities, are very many and often rather complex. We can distinguish three types of communications very much used by the chimpanzees:
   · the visual communication
   · the vocal communication
   · the tactile communication
The olfactive communication is negligible for this species.
ø Visual Communication
It occupies an important place in the society. The chimpanzees use many postures or many very significant gestures, such as for example:
  Open mouth threat by Yombé · Open mouth grin : the mouth is open, the commissures of the lips are drawn backwards and the teeth are visible; this display is used when an individual is threatened by another, higher placed in the hierarchy.
   · Open mouth threat : the mouth is open but the teeth are covered by the lips and the eyes aim at a congeneric; this display is used to frighten a subordinate.
   · Tense-mouth face : the lips are firmly compressed and the eyes aim at a congeneric; this display occurs as well before or during hunting towards a subordinate as before or during the copulation.
   · Play face : the eyes and the mouth are open but the teeth are not visible; this display occurs during the play with the other congeneric ones.
   · Flapping : a slap is given to congeneric with a movement applied downwards; this display takes place at the time of an aggression between females.
   · Social presenting : an individual adopts a posture quadruped with the croup directed towards the face of the receiver. This posture is carried out by the females towards the males or males subordinates towards dominant males. It acts of a posture of tender which occurs after an attack by the attacked individuals.
   · Charging display : an individual runs or launches stones, shakes objects such as branches, tambourine, slap the ground, stamp one's feet and pushes cries. This reaction characterizes in particular the adult males and occurs when dominating another individual meets after one rather long period or when the male alpha wants to ensure itself of its predominance towards its subordinates. Certain adult males carry out this demonstration at the time of torrential rains.
Vocal Communication
There are three principal cries or characteristic growls:
   · Pant-hoot : that consists of a series of noisy cries going up tone and often finishing themselves by howls. These cries are often given by males but it happens that the females use them. These cries resound when a site of food is discovered; it follows a regrouping of individuals a few days afterwards. This cry can also occur at the time of a "charging display".
   · Pant-grunt : they are weak growls emitted by subordinates towards the individual dominating in response to a demonstration of predominance like a "charging display".
   · Wraaa : this cry is emitted when the animals are afraid, in particular of something strange and new for them.
Tactile Communication
This type of communication between individuals takes a part quite as significant as the preceding ones; we can distinguish:
   · Reaching/touching : it is when an individual touches with the hand, that is to say the head, the back or the croup of a congeneric. It acts of a gesture of appeasing, of comfort in response to a " social presenting ".
  Grooming scene · Embracing : an individual surrounds a congeneric with one or two arms, facing, on the side or of back. This gesture is often observed between a mother and a frightened child.
   · Submissive mounting : a subordinate goes up dominating after being charged or being attacked and seizes the individual with the size, and sometimes catches the testicles with his feet.
   · Reassurance mounting : dominating a subordinate in response to a "social presenting goes up ".
   · Social grooming : an individual removes the parasites and dead skins of another. This makes it possible to maintain the bonds social and to reinforce them if needed. We frequently observes this behavior between males and especially of a subordinate towards dominating. In the common chimpanzee, that also occurs between members of the same family

Reproduction Aspect of the périneum of a female in heat (female on the left)
ø The common chimpanzee gives birth to a young person in general; the twins are rare. Gestation can extend from 202 to 261 days, with a 230 days average. The llabor can take place during all the year, the period of heat is approximately 35-36 days. During the oestrus (period of heat), the périneum (surface including the external anus and genitals) of the female is swollen.
There is an interval of a minimum three years between the births but five to six years of interval are more frequent when the young person survives. A female can give birth once a year if the baby is confiscated or killed at the time of the first months of his life.
ø During the first three months, the child is rocked by the mother when this one takes a sitting position. Until he is six months old, the child clings to the belly of his mother when this one moves then migrates on its back during the years which follow. Weaning takes place between 3 years and a half and 4 years and a half but the young baby can remain dependent of his mother during still of many years and it is frequent that it remains with her until he is 10 years old or more.
ø Puberty is reached at 7 years old for the two sexes and the females generally do not give birth before to have reached 13 or 14 years. They can however come into labor until she is 40 years old. The oldest females are more popular than the young people who must often leave the community, either temporarily, or definitively to go reproduce themselves.
ø The males, as for them, are not integrated into the social structure before 15-16 years. At the time of the reproduction, the male requests the copulation by showing its penis in erection and roughcasting its hairs. The majority of the copulations are dorso-ventral.

© H.E.L.P. International - 2006 // last update 22/02/2007