Yamakoshi / Poster
Research History and Conservation Status of Chimpanzees at Bossou, Guinea
Gen YAMAKOSHI1), Hiroyuki TAKEMOTO2), Tetsuro MATSUZAWA2)
and Yukimaru SUGIYAMA3)
1) Graduate School of Science, Kyoto University, Japan
2) Primate Research Institute, Kyoto University, Japan
3) Tokaigakuen Women's College, Japan
This review summarizes the findings from 40 years of research
on a chimpanzee group at Bossou, Guinea, and reports the current conservation status of
the chimpanzee group.
Research in the 1960's by the Dutch team consisted of short-term,
'testing-a-hypothesis' type projects, which focused on the chimpanzees' agonistic behavior
towards predators. They used a unique field-experiment method, with an artificial leopard,
to see how the chimpanzees responded to the stimulus.
In 1976, the Japanese team launched a long-term project. Although
diverse topics have been covered to date, a focus has been tool use. Starting with the
first substantial direct observation of nut cracking by wild chimpanzees, many other types
of tool use have since been described. A series of field experiments followed that
revealed many details about nut cracking by chimpanzees: hand preference, metatool,
developmental process, etc. Feeding ecology is a more recent topic, and the utilization of
oil palm as a 'keystone resource' when fruit is scarce, using two types of tool, proved to
have significant ecological importance. Unique social characteristics like male
immigration, close between-female relationships, and females' high reproductive
performances have been brought to light and require more ecological and genetic study to
understand their uniqueness comprehensively.
As for the conservation status of Bossou chimpanzees, the
population size has fluctuated, but has been essentially stable during the study period.
The reproductive parameters appear good, but juveniles of both sexes tend to disappear for
unknown reasons. The people of Bossou have a strong religious motivation for conserving
small patches of forest and the chimpanzees living there, and there is good collaboration
among the Bossou people, government institutions and researchers when dealing with
conservation problems. Current concerns seem to be the genetic isolation from a
neighboring chimpanzee population on Mt. Nimba, and crop damage caused by the chimpanzees.