WASHINGTON (Oct. 5, 2004)–Some of the mysteries surrounding central African chimpanzees and the ways they catch the termites they crave have been solved with aid of video cameras set up deep in the forests of the Republic of Congo.
Six months of continuous remote video monitoring captured 121 individual chimpanzees visiting six termite nests. For the first time, chimpanzees were extensively observed using two different types of tools they had fashioned to reach the termites and extract them. The recordings, made with unmanned cameras in the Congo’s Goualougo Triangle, provide a new window on the complexities of central African chimpanzee “culture,” culture under threat from steadily advancing logging as well as bushmeat hunting and the Ebola virus.
The research is reported in the November 2004 issue of The American Naturalist by authors Crickette Sanz of the Max Planck Institute and Washington University; David Morgan of Cambridge University and Wildlife Conservation Society, Congo; and Steve Gulick of Wildland Security. National Geographic and the Wildlife Conservation Society are key sponsors of the work.
“This really is great evidence of use of a complex tool kit among these chimpanzees,” said Agustin Fuentes, associate professor of anthropology at Notre Dame University, who reviewed the
team’s scientific paper.
Chimpanzees previously have been observed using fishing probes to catch termites at many sites across Africa, but puncturing or perforating of termite nests is known only in central Africa. What was not known before was the precise techniques these chimpanzees use on their termite-fishing expeditions, methods that may be unique to this population.
In the tapes various chimpanzees are seen approaching one of two types of termite nests. For elevated mounds, the chimps first use a small, short stick to carefully perforate the nest surface; they then switch to a “fishing probe” — another type of stick — to extract the insects. For subterranean nests, the chimps use a longer “puncturing stick” to create an underground tunnel and then insert a fishing probe to pull out termites.
One sequence shows an adult chimp perching on the edge of an enormous termite mound, nimbly switching back and forth between puncturing stick and fishing probe and gobbling termites. Others show mothers and their young cooperating to trap the insects.
“Sometimes when they arrive at the subterranean mounds, they have brought their tool kits — puncturing sticks and fishing probes — with them,” Sanz reported. The cameras picked up 45 such occasions. And after they eat, the chimps sometimes leave their tools behind — to reuse the next day.
To get into subterranean mounds, “the chimpanzee visually scans the surface of the soil and may even walk to several old fishing hole locations to inspect them,” the researchers write. After choosing a site, the chimp rakes away debris and points the end of the stout stick at the nest, pushing it into the ground with both hands. Chimps often are seen placing a foot on the stick and using their body weight to leverage the puncturing stick into the ground, Sanz said.
The fishing probes used for the two types of nests are similar to each other and often sport brush tips fashioned by the chimps. “The footage shows a female chimp taking a stick and pulling it through her teeth — intentionally modifying the end like a paint brush,” Sanz said. “This is a very effective way of gathering termites.”
Fishing probes, used for both types of nests, are most often made of only one species of herbaceous stem, which is gathered a considerable distance from the termite nests. To determine why the apes stuck to the one herb species, Sanz and Morgan tried others and found that they were not as effective at extracting termites.
Video monitoring devices recorded 69 visits at several nest locations throughout the chimp community’s range. Adult females were the most frequent visitors to the nests, followed by adult males. Chimpanzee visits to the termite nests ranged from a few seconds to nearly an hour; the average stay was 12 minutes.
“The cameras have given us information that most researchers only can get through years of habituating the chimpanzees to the presence of humans,” said Fuentes, of Notre Dame. “Even better, the data are unaffected by interaction with humans.”
The cameras even captured intimate family moments, as infants watched their mothers termite fishing and then were passed the tools to give it a try. “Some of the infants are clumsy — arms all over the place — and others are pretty efficient at bringing termites out and pulling them off the tools,” Sanz said. Infants also are seen begging their mothers to share the tasty bites or “fishing” for them alongside their mothers.
The community of 54 chimps studied lives under the protection of Congo’s Nouabele-Ndoki National Park in an area annexed last year to protect them. The study area also encompasses chimpanzees living outside the park, who are threatened by logging that destroys not only the termite mounds but also the very places the chimps inhabit.
“Places these chimps have been visiting for generations are being destroyed or severely affected,” said co-author David Morgan. “They’ve already stopped using certain mounds because of human traffic in the area, so we will lose the chance to document that chimpanzee community’s culture. We still have a chance to preserve some of these intact forests in the Congo Basin and the unique chimpanzee cultures that reside within them.”