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Why can encounters between different chimpanzee communities become violent?

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A common chimpanzee (Pan troglodytes) sits on a rock holding a long blade of grass in its mouth, with dense green foliage in the background. — chimpanzee The West African, or masked, chimpanzee (*Pan troglodytes verus*) is a critically endangered subspecies of chimpanzee.

Encounters between different chimpanzee communities are often hostile because these primates are highly territorial and engage in intraspecific aggression to protect their resources.12

Adult males frequently conduct boundary patrols to defend their home range from intruders. When these groups encounter one another, violence can erupt as a result of competition for food and mates. In some instances, a larger group may purposefully invade a smaller neighbouring territory, which can lead to lethal outcomes for the members of the smaller group.12

This violence is driven by between-group competition, and in extreme cases, it may involve infanticide or cannibalism. By attacking neighbouring groups, chimpanzees effectively protect their local food supply and reduce competition within their environment. Such aggressive strategies are considered adaptive, as they help maintain the integrity of a community's territory and ensure the survival of its members.134