Data and code from: Correlates of individual participation in boundary patrols by male chimpanzees

Group territory defense poses a collective action problem: individuals can free-ride, benefiting without paying the costs. Individual heterogeneity has been proposed to solve such problems, as individuals high in reproductive success, rank, fighting ability, or motivation may benefit from defending territories even if others free-ride. To test this hypothesis, we analyzed 30 years of data from chimpanzees (Pan troglodytes) in the Kasekela community, Gombe National Park, Tanzania (1978-2007). We examined the extent to which individual participation in patrols varied according to correlates of reproductive success (mating rate, rank, age), fighting ability (hunting), motivation (scores from personality ratings), costs of defecting (the number of adult males in the community), and gregariousness (sighting frequency). In contrast to expectations from collective action theory, males participated in patrols at consistently high rates (mean ± S.D. = 74.5 ± 11.1% of patrols, n=23 males). The be...

群体领地防御面临集体行动困境（collective action problem）：个体得以搭便车（free-ride），无需付出任何成本即可获益。个体异质性被提出可解决此类问题，即繁殖成功率（reproductive success）、社会等级（rank）、战斗能力（fighting ability）或动机较高的个体，即便他人搭便车，仍能从领地防御中获益。为验证这一假设，我们分析了坦桑尼亚贡贝国家公园卡塞拉群落黑猩猩（Pan troglodytes）1978年至2007年间共计30年的观测数据。我们考察了个体参与巡逻行动（patrols）的频率与多项指标的相关性：繁殖成功相关指标（交配率、社会等级、年龄）、战斗能力（狩猎行为）、动机（人格评分得分）、叛逃成本（群落内成年雄性数量）以及社交性（gregariousness，目击频率）。与集体行动理论的预期相悖，雄性个体的巡逻参与率始终维持在较高水平（平均值±标准差=74.5±11.1%，n=23只雄性）。