The researchers also followed the wild chimps around their territory and determined that the primates tended to stay quiet around the borders of their range, probably because they did not want to risk alerting rivals to their presence.

The scientists discovered that, although chimps usually call out when they find a plentiful food source, the Gombe primates "stayed strikingly quiet" when they raided humans' banana plants just outside of the park.

Anne Pusey, a professor of ecology, evolution and behavior at the University of Minnesota, who is also a chimp expert, told Discovery News that she was not surprised by the findings. She said chimpanzees even motion each other to be quiet.

"When male chimpanzees are on patrol in border areas, they move very quietly and even threaten observers (with an arm threat) who are following them if they make a loud sound, like stepping on a dead branch," Pusey said.

She added that some chimps actually tiptoe over rocks or tree roots to lessen their noise.

Wilson hopes his study will serve to help stave off the extinction of the great apes in the wild.

He said, "As our closest living relatives, chimpanzees and other great apes can provide us with enormously valuable information about what our ancestors may have been like and how we evolved.

"At the same time, great apes face many threats from people, including habitat destruction, hunting for meat, disease, and capture for the pet and entertainment trade. If we do not take steps to reduce these threats, great apes will soon follow our other close relatives into extinction," he said.

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Name: Chimpanzee (Pan troglodytes)
Primary Classification: Hominidae (Great Apes and Humans)
Location: Equatorial Africa
Habitat: Savanna, woodlands, swamps and rainforest.
Diet: Fruits, leaves, seeds, bark, honey, ants, termites and occasionally meat.
Size: Averages 3 to 5 ft in height and 100 to 175 lbs in weight.
Description: Black or brown hair; hairless face that turns dark with age; bulging eyebrows; protrusive lips; very long arms; opposable thumbs and big toes; males have large canines; no ail.
Cool Facts: It is one of the only animals that uses tools, such as a twig that it pokes into termite nests and removes when covered in insects. It is our closest relative, sharing about 98 percent of our genes.
Conservation Status: Endangered
Major Threat(s): Habitat loss and poaching
What Can I Do?: Visit The Jane Goodall Institute for information on how you can help.

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