Abstract
Adult female orangutans have large but stable home ranges, varying from as little as 150 ha in some forests up to 850 or more in others. Spatial variation in availability of fruit of key tree species or spatial variation in habitat-wide fruiting peaks appears to be the driving force behind major movements within the range. Larger home ranges are found in more frugivorous subspecies, and at the level of study sites, where habitat mosaics are coarse enough for individual orangutans to cover multiple habitats. In larger home ranges, overlap is also larger. The chapter confirms the presence of female clusters of relatives with highly overlapping home ranges who show preferential association.