Due to high levels of exploitation, habitat loss and habitat degradation, Pan troglodytes has experienced such a significant population reduction over the past 20 to 30 years that it is now on the IUCN (International Union for the Conservation of Nature and Natural Resources) Red List of Endangered Species. The Nigerian chimpanzee, Pan troglodytes ellioti (Gray 1862), is the most endangered of the four subspecies of chimpanzee. It has the smallest distribution and smallest population size, estimated in 2011 to be between 3,500 – 9,000 individuals. P. t. ellioti was first recognized as a distinct subspecies in 1997, and in 2008 an Action Plan Study Group was set up with the goal to determine the priority sites for its conservation and the actions that should be taken to ensure its long-term survival. The Action Plan was published in 2011 and this thesis is timely as it begins to answer some of the questions deemed important in the action plan. The overall aim of this study was to explore the ecology and behaviour of a small, isolated montane population of P. t. ellioti with the aim of making a useful contribution to future recommendations for the management and conservation of this subspecies. Specifically, I estimated the density of chimpanzees in Ngel Nyaki Forest Reserve, Taraba State, Nigeria and investigated their nesting ecology, elementary technology, diet, seed dispersal and the viability of seeds dispersed by the chimpanzees. I estimated chimpanzee density by using a combination of direct (direct observation) and indirect methods using nest counts. My investigation of nesting ecology concentrated on identifying habitat variables that influenced choice of nesting site. I assessed elementary technology by locating and describing both manufactured artefacts and unmanufactured objects, and I then located evidence from the surrounding environment to establish details about their presence or absence. Chimpanzee diet was assessed using evidence from faecal samples and artefacts. In order to identify preferences and agents involved in removal of various seed species ingested and dispersed by chimpanzees I set-up a series of experiments using plots into which seed piles were added. Lastly, I compared the rate of germination of conspecific seeds which had been passed through a chimpanzee gut with those that had not been dispersed.