The bonobo has a discontinuous range in the low-lying central Congo Basin of Equatorial Africa, south of the Congo River. Their range extends from the Lualaba River in the East, to the Kasai/Sankuru Rivers in the South, and to the west as far as to the Bolobo village and around the Lake Tumba/Lac Ndombe area. Although the extent of their potential range is estimated at approximately 500,000 kmÂ² (Thompson et al. 2003), recent evidence of previously unsurveyed areas has detected bonobo presence throughout their historical area of distribution. Bonobos occur in small populations whose gene flow is determined by riverine barriers. Due to the bonobosâ dispersal patterns, the effective population size of males is smaller than that of females. Analyses of population genetics suggest that bonobo populations have a stable population history (Eriksson et al. 1999, 2004). Despite new surveys by various NGOs, the southern part of the Congo Basin, including the area south of the Kasai River, has not been surveyed.