The home range of the Bossou chimpanzees is clearly dominated by secondary and scrub forest, with primary forest only covering about 1 sq. km. It is additionally surrounded by savanna vegetation interspersed with occasional gallery forests, which connect to small adjacent forests, beyond which lie, on the southeastern side, the Nimba Mountains. The Bossou chimpanzees mostly confine their daily activity within a core area of about 6 sq. km, though they sometimes travel to adjacent forests using the few remaining gallery forest corridors that extend their home range to around 15 sq. km.

Different communities of wild chimpanzees possess different tool use repertoires. However, not all of this regional and local variation can be explained by the demands of the physical and biotic environments in which they live. Many of these behavioral variants are socially learnt and are maintained from one generation to the next. These have now been acknowledged as representing cultural behaviors (Whiten et al, 1999).

The home range is dissected by a narrow road (3m wide) which is used by pedestrians and a newly expanded larger road (12m wide at the crossing point), which carries trucks, cars, motorbikes and pedestrians.The roads are forested up to the edge and separated by secondary forest and plantations.

Road-crossing presents a new situation that calls for flexibility of responses by chimpanzees to variations in perceived risk. The chimpanzees at Bossou, Guinea, West Africa, employ a phylogenetically-old mechanism to adapt to a more recent dangerous situation. The positioning of dominant and bolder individuals, in particular the alpha male, changed depending on both the degree of risk and number of adult males present; dominant individuals act cooperatively with a high level of flexibility to maximise group protection. Differences in progression orders may reflect the division of roles, and the collaboration among males to protect the females and their off-spring. This may also help shape hypotheses about emergence of hominoid adaptive social organization.