Diurnal Primates: Estimates and Conservation Issues

Abstract

Data were collected for a period of 38 weeks (9.5 months) covering both rainy and dry seasons to identify diurnal primate species, document group compositions, and to estimate both encounter rates δ and densities \(\overline{\varpi }\) at Malebo region. Three species were observed in six groups: De Brazza’s monkey, Mona monkey, and red tail monkey along a 10 km long trail. The mean relative abundance for all three species δ = 0.6 groups/km ± 0.2 (SD). The mean group sizes for red tail monkeys \(\overline{X} = 7.3\) individuals/group ± 0.12 (SE), larger than any of the three systematically monitored in the region and De Brazza’s monkey, with \(\overline{X} = 2.5\) individuals/group ± 0.23 (SE) had the smallest group size. The most encountered species was Mona monkey (sighting probability µ = 0.82 sightings/visit). The overall mean density \(\overline{\varpi } = 0.28\) individuals km−2, within the range = [0.13–0.38] individuals km−2. The red tail monkey was the most abundant (\(\overline{\varpi } = 0.38\) individuals km−2) followed by Mona monkey (\(\overline{\varpi } = 0.32\) individuals km−2) and De Brazza’s monkey (\(\overline{\varpi } = 0.25\) individuals km−2). Comparisons with other areas in Tropical Africa indicated that group sizes, relative abundance, and densities in this region were lower. Despite the potential of other ecological processes (e.g. differences in habitat types, food availability, etc.) in the region to deplete primate populations, bushmeat trade was arguably the main reason for lower primate abundance in this region. Immediate conservation actions were called upon to help conserve some of the most important forest galleries from hunting to preserve the primate populations.