The release of wild-born orphaned chimpanzees Pan troglodytes into the Conkouati Reserve, Republic of Congo

Habitat destruction and the subsequent increase in the lucrative yet illegal bushmeat trade continue to threaten wild chimpanzee populations. The hunting of African great apes appears to be increasing still. This trade has caused a persistent rush of orphaned apes toward sanctuaries, where their future is limited in captivity. Considering both the seriousness of this problem and the immense cost of caring for these orphans, HELP-Congo (Habitat Ecologique et Liberte des Primates), a Congolese non-governmental organisation, has been using reintroduction as a tool to address the fate of orphaned chimpanzees. So far, 20 chimpanzees have been reintroduced at four different times in the Conkouati Reserve, Republic of Congo. Since the first chimpanzees have been released, a team of scientists and local field research assistants closely monitors them. To date, more than 6, 000 h of direct observation have been carried out. The overall survival rate is in excess of 75%. This scientific monitoring aims at providing data on chimpanzee reintroduction and will help to design guidelines for the decision-making process, the preparation, and the implementation of chimpanzee reintroduction. In this paper, we describe the protocol followed by HELP to release 20 chimpanzees between 1996 and 1999