TERRITORIAL AND LETHAL AGGRESSION
Chimpanzees are well known for their territorial behavior. They are among the few animals that engage in between-group coalition aggression that results in fatalities. Encounters between communities typically take place during boundary patrols.
Communities defend an area within the forest known as a territory. This differs from the home range of an individual, which is not defended but remains within the territory of the community in which the individual lives. Males will form border patrols and walk the perimeter of their community territory looking for neighboring community members who might try to invade their territory.
The main difference between the robust or common chimpanzee and other primate multi-male groups is that in the former, the males remain in their natal communities while females may disperse to neighbouring communities, usually once they have reached sexual maturity. This allows male chimpanzees to form strong bonds and results in close genetic ties. As a male-dominant, hierarchical species, these alliances between individuals may allow them to achieve high ranks within the community. Several factors influence territory size, including the number of individuals in the community, habitat quality (with regard to food availability and quality), pressure from neighbouring communities, and population density.