Global primate conservation issues and a case study from Tanzania

A recent review of global primate conservation revealed that out of 504 species in 79 genera across the tropics, alarmingly, about 60% of species are threatened with extinction and about 75% have declining populations. This situation is the result of escalating anthropogenic pressures on primates and their habitats, leading to extensive habitat loss through the expansion of industrial agriculture, large-scale cattle ranching, logging, oil and gas drilling, mining, dam building and the construction of new road networks in primate range regions. Other important drivers include increased bushmeat hunting and the illegal trade of primates. Addressing primate conservation requires a diversity of strategies, from improving human conditions in range countries and strengthening the coverage and efficiency of protected areas, to mitigating illegal trade, restoring habitat and reintroducing species. For many of these strategies to be properly designed, and their success evaluated, efficient monitoring of threatened primate populations is advocated as a critical prerequisite. We build on this background to present a case study from a long-term monitoring and conservation programme in the Udzungwa Mountains of Tanzania, which is a global hotspot for primate endemism and conservation. Arboreal primates were monitored using counts from line transects established in 2 large moist montane forest blocks collected for over 10 years, cumulating in nearly 1,400 transect repetitions for over 5,200 km walked overall. The two forests differ in protection status, one being relatively well protected and one unprotected. Results of temporal trends in abundance show clearly how hunting and habitat degradation drove the most vulnerable primate species to near extinction in the unprotected forests. We elaborate on field and analytical routines related to comparability of data from multiple years. Results were used to lobby for conservation with relevant authorities, which contributed to the upgrading of the protection status of the unprotected forests.