Chimpanzee

Characteristics

The great ape family includes humans, chimpanzees, gorillas, and orangutans. Great apes have no tail nor ischial callosities. The dental structure is the same for all great apes and well as the basic facial structure and large brain cavity. Humans are the only great apes without opposable big toes. Males are usually larger than females. Great apes have complex social structures with varied and important communication.

Species Specifics

There are four subspecies of chimpanzee, which are mostly distinct by their geographic location. Chimpanzees are covered in black fur, except for their palms, ears, faces, and soles of their feet which are pink to black bare skin. Chimpanzees are "knuckle-walkers," who walk on all four limbs. Their arms are longer than their legs because of this behavior.

Physical Characteristics

Apes, including chimpanzees, have color vision. They have opposable big toes, as well as thumbs, making them very well adapted to being in the treetops. A chimpanzee's arm span is 1.5 times that of their height which aids in knuckle-walking and climbing. As a chimpanzee ages, the hair on both sexes' faces and the males' backs will start to lighten and turn grey.

Ecology

Habitat

Humid forest, deciduous woodland or mixed savanna; presence in open areas depends on access to evergreen fruit-producing forest

Distribution

Males may travel up to 3 miles a day while females travel 2 miles.

Diet

Feed on a wide variety of foodstuffs (over 80 different items have been cataloged) with the largest proportion consisting of fruit and young leaves. In long dry seasons, buds and blossoms, soft pitch, stems, galls, honey, bark and resin, seeds and nuts are also eaten. Animal prey makes up as much as five percent of the diet, with social insects, such as ants and termites, providing the largest amounts. On rare occasions small game (monkeys, pigs, and antelope) is hunted. Feeding is essentially an individual activity, but after a cooperative hunt may share morsels in response to begging by others. There seem to be "cultural" differences between groups of chimpanzees in the variety of food taken and the techniques for processing it. West African chimps use wood and stone tools as hammers to open nuts.

Ecological Web

Chimpanzees are mostly frugivorious (fruit eaters) which makes them important seed dispersers.

Activity and Behavior

Activity Pattern

Chimpanzees will travel and forage all day and climb into trees at night to make their individual nests for sleeping. Chimpanzees have a territory range but may sleep in different trees and new nests every night.

Behavior

They are one of the few mammals that manufacture and use "tools." They often feed by poking a twig or vine into a termite nest hole. When the twig has become covered with insects, they pull it out and nibble them off. They also use sticks to enlarge holes so that ants can be reached. Some populations chew leaves to make them more absorbent and dip for water from holes in trees. Many also use leaves to clean the body. West African chimps use stones to crack hard seeds. Chimpanzees have been seen in the wild, eating plants with medicinal properties. Chimpanzees show extreme intelligence; they can recognize themselves in a mirror which is a sign of high emotional and intellectual intelligence. Like many primates, chimpanzees do not swim and avoid being in deep bodies of water.

Social Behavior

Chimp communities are made up of 15 to 120 animals. These communities lack a definite leader and are usually split into a number of subgroups which are temporary and change in composition within a matter of hours or days ("fusion-fission" groups). Mothers often travel alone with only their offspring. Males seldom or never leave the community into which they were born, whereas most females migrate to a new community during an adolescent estrus period. In male relationships, tension is routinely expressed in dominance interactions when parties meet, but males also spend much time grooming each other. They form a loose dominance hierarchy. Chimpanzees communicate in many ways: verbal communication with up to 34 different vocalizations, facial gestures such as showing teeth as a sign of aggression, body language such as involuntary piloerection (hair standing erect) showing excitement, and captive chimpanzees have even been taught sign language. Communication is very important because skills such as tool-making and foraging are learned behaviors. Offspring stay with their mother for years observing her and mimicking her.

Reproductive Behavior

Females can give birth every 4-7 years, or sooner if the previous offspring doesn't survive. Puberty lasts for about three years in males and females. During this time, a female may have a menstrual cycle but is not fertile. A female can have 9 offspring in her lifetime, even into her forties, though usually only three of those offspring survive. While females and males will mate with multiple partners, dominant males may try to prevent other males from breeding with certain females. During the 6-day fertile part of a female's 36-day cycle, her genitals and the skin around them will increase in size and become pink or red. This swelling is called tumescence. Sometimes a male and female will move to the periphery of the group for up to 3 months. During this "consortship" they will be very silent to keep attention away from them to help maintain their bond. This is an important way for both to ensure the paternity of an offspring. There appears to be a lot of female choice in chimpanzee breeding. A female will consent to a consortship and choose to stay or remain. When in the larger group and breeding with many males, a female often appears to make clear choices about with which male to mate.

Offspring

Births are usually single though occasionally twins. At birth, they weigh 4 pounds. They have black fur right away but their skin is very pale pink and there is a white tufted tail which disappears as they grow. At first, offspring cling to their mother's stomach and will then change to a more piggy-back style hold on their mother's back. Chimpanzees are weaned by 4 to 5 years old.

Conservation

Status

Although there may be as many as 300,000 chimps in the wild, chimp populations have been reduced and fragmented by human encroachment into their habitats. In addition, hunting by people for bushmeat or commercial exportation for the pet trade or scientific research has led to them being placed on Appendix II (threatened) of CITES, listed as endangered by the IUCN, listed as Class A under the African Convention on the Conservation of Nature and Natural Resources, and considered endangered by the U.S. Fish and Wildlife Service.

Historical

Chimpanzees were previously found in 25 African countries but now are only in 21. There are estimates from 1900 of 1 million chimpanzees in the wild.

Current Threats

Our Role

Oakland Zoo partners with Kibale Fuel Wood Project to protect the Kibale National Park in Uganda. It has one of the densest populations of chimpanzees. The project assists families in using sustainable stoves to lessen deforestation, plants trees in the community, and does outreach and education. The Oakland Zoo sells "Beads for Chimps," beads and jewelry made by women living near the Kibale National Park. Oakland Zoo also partners with the Budongo Snare Removal Project, spearheaded by the Jane Goodall Institute, to remove bushmeat snares from the forests where chimpanzees live. These snares loop around a limb and as the chimpanzee tries to get free, it tightens. Many chimpanzees, even if they are rescued, permanently injure or lose a limb from this trauma.