Pan troglodytes vellerosus, the Nigerian-Cameroon chimpanzee, is the most recently recognized chimpanzee subspecies and is categorized as Endangered on the IUCN Red List. Current estimates, based on a range of sources, suggest the total number of individuals to be between 5,000–8,000. This study used a transect survey to estimate the population of P. t. vellerosus within the Nigerian submontane forest of Ngel Nyaki Forest Reserve, in Taraba State. The forest is an isolated fragment of c. 7.5 km2. Total nest building population size (n = 12.5) and population density (1.67 weaned chimpanzees km-2) were estimated from the number of nests observed along line transects. The maximum nest-group size (n = 11) suggests that this population comprises a single community. The low estimated population numbers within Ngel Nyaki forest, compounded by the forest's isolated location, highlight the urgent need for conservation action.
