In that issue of Current Biology with the report about bonobo hunting, there is also a short correspondence describing the decline of chimpanzee populations in Côte d’Ivoire:
The pressing need to base conservation policy on up-to-date data is underlined by the situation in Cte d'Ivoire. For instance, Marahou NP is listed as a priority site with an estimated population of 900 chimpanzees (information from the Woods Hole Research Center's website); however, our 2007 survey of 167.5 km of transects distributed throughout the park yielded a conservative population estimate of fewer than 50 individuals (unpublished data). Even in Ta NP, thought to represent one of the main refuges for chimpanzees within Cte d'Ivoire, our 20062007 survey along 362 km of transects revealed that only about 480 individuals survive, a tenth of the assumed population size (Campbell et al. 2008:R904).
The human population has increased by 50% since 1990, when the last attempt at a chimpanzee census was finished.
Campbell G, Kuehl H, Kouamé PN, Boesch C. 2008. Alarming decline of West African chimpanzees in Côte d'Ivoire. Curr Biol 18:R903-R904. doi:10.1016/j.cub.2008.08.015