Ranging and territoriality in African Apes

Defendability indices are higher in chimpanzees and bonobos than in mountain gorillas, but do not differ significantly among chimpanzees, bonobos, and western gorillas.

• Why it matters: The economic defendability hypothesis predicts territoriality should track how well home ranges can be defended, yet African ape intergroup aggression varies sharply across species.
• What they did: The authors compiled comparable measures of yearly home range size, daily travel distance, and defendability indices from one population per nonhuman African ape species, then integrated these with published datasets.
• The result: Bonobos show larger home ranges and longer daily travel distances than chimpanzees and gorillas, and overall findings suggest economic defendability alone cannot explain interspecific territoriality differences.

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