Pan troglodytes ssp. troglodytes (errata version published in 2016)

Abstract

Assessment Information: Pan troglodytes troglodytes has a very large geographic range (over 700,000 km2) and a relatively large population size, currently estimated at about 140,000 individuals (Strindberget al. in prep). However, this subspecies has experienced a significant population reduction since the 1970s. Between 1983 and 2000, the country of Gabon lost half its great ape population to poaching and disease, at an annual rate of decline 4% (calculated from Walsh et al. 2003). A more recent study examined nest survey data collected between 2003 and 2013 across the entire range of the taxon and created a predictive model to map Central Chimpanzee density and distribution (Strindberget al. in prep). Although the results show no statistically significant decline during those 10 years,Central Chimpanzee populations remain highly vulnerable to poaching and disease. Due to their slow life history and a generation time estimated to be 25 years, Chimpanzee populations cannot sustain high mortality levels, whether disease-induced or caused by humans. Given the scale of the poaching problem across Central Africa, this taxon is likely to be experiencing declines significant in terms of the population status, which we do not have the statistical power to detect. It is suspected that this reduction will continue for the next 30 to 40 years due to illegal hunting and expansion of the commercial bushmeat trade, and to habitat loss and degradation occurring at an increasing rate as a result of expanding human activities. The causes of the reduction, although largely understood, have certainly not ceased and are not easily reversible. The predicted continuation of the population decline is a precautionary approach based on the rapidly-increasing human population density in the region, and the expansion of land clearing for industrial-scale agricultural plantations, which requires the clearcutting of forest and is likely to accelerate in the next two to three decades. The effects of climate change will also become increasingly evident. At the same time, the threat of emerging infectious diseases is ongoing; there is, for example, evidence that Ebolavirus will continue to spread (Walshet al. 2005), which would have devastating consequences for Central African great ape populations. At a conservative rate of loss of 1% each year, the population reduction over three generations (75 years) from 1975-2050 is likely to exceed 50%, hence qualifying Central Chimpanzees as Endangered under criterion A.