Relative abundance and distribution of black-and-white colobus monkey (Colobus guereza guereza) and recommendations for its conservation in the northwestern Ethiopia

Abstract

Primates in the tropics are highly vulnerable to habitat loss and fragmentation as they depend on the forest for survival. Thus, reliable population and distribution data are crucial to identifying priority sites for conservation and designing effective management plans in the deforested region. To date, the population size and distribution of black-and-white colobus monkeys (Colobus guereza guereza) are unknown along the Ethiopian Highlands. Therefore, this study aimed to determine the relative abundance of black-and-white colobus monkeys and their current distribution pattern in the Awi Zone of the northwestern Ethiopia. We conducted population survey of black-and-white colobus monkeys using line transects between Oct 2020 and Sep 2021 in 27 forest patches of the region. We surveyed 27 forest patches and found black-and-white colobus monkeys in all patches. Overall, we recorded 328 group sightings of black-and-white colobus monkeys in these forest patches ranging between 1859 and 2557 m asl. We counted a total mean of 2897 individuals ranging from 5–16 individuals per group (mean = 8.8, SD = 2.5) within the sampling transects. Overall, the sighting encounter frequency of this monkey was 5.5 groups/km, while the relative mean population abundance was 48.2 individuals/km. Our study offers the first baseline information for future absolute abundance and population density estimates of black-and-white colobus monkeys and the forest patches they inhabit. Thus, this region should be considered as key habitat for future black-and-white colobus monkeys and other conservation initiatives. Establishment protected areas (national parks), improved law enforcement, population trend monitoring, and engagement with adjacent local communities are imperative to secure the long-term survival and conservation of black-and-white colobus monkeys and their habitats in the region. In addition, conservation measures like educational awareness programs, modern beekeeping, and alternative biofuel use should be initiated to stop further deforestation.