Despite 11 years of civil war in Sierra Leone, it appears that the mammal fauna of the project zone has survived relatively intact and that the project zone continues to be an important site for the conservation of threatened Upper Guinea forest wildlife, and the most important site for these species in Sierra Leone. No large mammal species was extirpated during the war and previously unrecorded species have been discovered in recent years. Some of the most threatened species continue to have healthy populations in the forest, especially primates, and showed little or no sign of reduced abundance. However, the population of African forest elephants has collapsed during the war, with only a few individuals remaining from approximately 110 in the mid-1980s (Lindsell et al 2011).
Eleven primates are known to occur in the project zone, including one ape and three prosimians. The Endangered Western red colobus is common but is mostly restricted to the less disturbed areas of the central and northern parts of the project area. The Vulnerable Diana monkey, Sooty mangabey and Western pied colobus are abundant and widespread but the only Near-threatened primate, Olive colobus seems to be rare (Klop et al, 2008).
The Endangered Chimpanzee is relatively widespread throughout the project zone. Based on transect sampling of nest counts in 2009, an average population density of 0.27 chimps per km2 was estimated (Ganas 2009), with highest densities occurring in the northern part of the project area. These figures compare favourably to other West African forests. When extrapolated over the entire forest this density gives a total population of 303 in the project zone (Ganas 2009).
The Endangered Pygmy hippopotamus occurs in a many areas, most notably along the Mano/ Moro River. This area consists of a mix of floodplains dominated by herbaceous vegetation and patches of riverine forest. There is very little information on the ecology of this species so it is hard to make inferences about likely population sizes. Most of the riverine forest is in the leakage belt of the project zone and so floodplain areas in the community forest may be essential for the conservation of this species in Sierra Leone (Hillers and Muana 2011).