Zanzibar red colobus on Pemba Island, Tanzania: population status 38 years post-introduction

Summary

The Zanzibar red colobus monkey (Procolobus kirkii), an Endangered primate endemic to Zanzibar with only 2,000-2,500 individuals remaining, was introduced to Pemba Island's Ngezi-Vumawimbi Nature Forest Reserve in 1973 when Tanzania's Zanzibar Forestry Department released 15 animals (5 males, 10 females) captured roughly 150 km away on Zanzibar, in what may have been the first primate translocation ever attempted for conservation purposes in Africa; no records survive of the original goals, success indicators, or capture and transport methods used. No monitoring occurred for the first 17 years. Censuses in 1991, 1992, 2000 and 2005 each found no more than one small group of at most six animals, though local interviews suggested two to three additional undetected groups may have existed. A thorough 2011 census by two primatologists over five days located two groups of at least 7 and 8 animals plus feeding evidence for three more, concluding the population had grown to at least 35, and likely closer to 40, some 38 years after introduction, more than double the founding number but still small and possibly suffering inbreeding depression given the narrow genetic base. A comparable 1977-1981 translocation of 36 colobus to Zanzibar's own Masingini Forest grew 67% within 13-17 years, and remained present as of 2011. Major difficulties included the species' cryptic, hard-to-census behavior, chronic underfunding, and the possibility of undetected poaching. The project rates itself Partially Successful, noting the introduced population persists and has grown, but remains small, isolated and inadequately monitored.