The Ebo forest is home to the most endangered form of chimpanzee – the Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti), which may number as few as 3,500 individuals remaining in the wild. Ebo is among the few forests in Cameroon and Nigeria that has been classified as of ‘exceptional priority’ for the conservation of Nigeria-Cameroon chimpanzees by the IUCN Primate Specialist Group (Morgan et al. 2011).

The Ebo chimpanzees are also special because they appear to have a unique suite of tool use behaviours. In particular, as well as constructing a ‘toolkit’ for extracting termites from underground termitaria, they use stone and wooden hammers to crack open hard-shelled Coula edulis fruits (Morgan and Abwe 2006). Before we discovered this behaviour, it was though that only chimpanzees living in West Africa, to the west of a large river in Cote d’Ivoire (Pan troglodytes verus) used such tool to crack open fruits to access the nutritionally high value seeds inside these fruits. Our colleagues working with Nigeria-Cameron chimpanzees in Gashaka-Gumti National Park, Nigeria (Gashaka Primate Project) have not witnessed this behaviour there, and interesting questions about how such behaviours emerge, spread and perhaps disappear remain to be answered.