Supplementation of the black and white ruffed lemur population with captive-bred individuals in the Betampona Reserve, eastern Madagascar

Summary

The Madagascar Fauna Group supplemented the small, isolated black and white ruffed lemur (Varecia variegata) population, estimated at 35 to 40 individuals, in the 2,228 hectare Betampona Reserve in eastern Madagascar, aiming to reinforce genetic diversity and reduce inbreeding risk using genetically surplus, behaviorally screened captive-bred animals. Following population modeling and detailed botanical surveys to confirm food availability at release sites, the project carried out three releases coordinated with Madagascar's CITES authority: November 1997 (three males, two females), November 1998 (one male, three females), and January 2001 (three males, one female). Intensive post-release monitoring through all-day behavioral follows continued until January 2002, with lower-intensity monitoring by trained staff ongoing since. Of the thirteen lemurs released, three (23 percent) were still surviving in the reserve at the time of reporting and five (38.5 percent) had successfully integrated with and bred into the resident wild population, producing multiple offspring across several years; other individuals were lost to fossa predation, malnutrition, or disappearance. The continuous presence of project personnel also strengthened overall reserve protection, benefiting other threatened species such as indri and diademed sifaka. The project rated itself Successful, citing survival beyond one year without supplementary feeding, confirmed interbreeding contributing new genes to the wild population, and improved reserve-wide protection through sustained on-site presence and community outreach.