Chimpanzee

The intelligent, social chimpanzee has a wide range of sounds and gestures for communication and is probably one of the most expressive of all animals. Thickset and robust, but more lightly built than the gorilla, the chimpanzee has a strong body and long limbs, the powerful arms being longer than the legs. Its hands and feet are narrow and long, with opposable thumbs on the hands. Males are slightly larger than females. There is great variability in the color of hair and facial skin, but the hair is generally blackish and the face light, darkening in older individuals. The rounded head bears broad, prominent ears, and the lips are mobile and protrusible. Chimpanzees climb well but spend most of the time on the ground, where they generally walk on all fours, even though they stand erect on occasion, as when their hands are full of food. 

Their social structure is more variable than that of the gorilla. Rainforest animals live in troops of males, of females with young, of males and females with young, or of adults of both sexes without young. The composition of the troop often changes. Savanna chimpanzees generally live in more stable troops of 1 or more males, several females and their young. They occupy a home range, the size of which depends on the size of the troop and on the food supply. Neighboring troops meet with much noise and communication, but there is usually little aggression.  Active in the daytime, chimpanzees rise at dawn and feed mainly on plant material, such as fruit, nuts, leaves, shoots and bark, and on eggs and insects. They will use stems or twigs as tools, to extract termites or ants from their hiding places. Savanna chimpanzees will kill young animals for food by holding them by the hind limbs and striking their heads on the ground. At night, chimpanzees usually sleep in the trees, each making its own nest with interwoven, broken and bent branches. Young under 3 years old sleep with their mothers. Females have regular periods of heat, with swelling of the genital region, and may mate with all the males in the troop. Usually 1 young is born, sometimes twins, after a gestation of 227 to 232 days. The young animal lives closely with its mother for 2 to 3 years.