Shibata Shohei, Furuichi Takeshi, Hashimoto Chie
Wildlife Research Center, Kyoto University, Inuyama 484-8506, Japan.
Japan Society for the Promotion of Science, Kojimachi, Chiyoda-ku, Tokyo 102-9983, Japan.
Animals (Basel). 2022 Aug 30;12(17):2240. doi: 10.3390/ani12172240.
Several studies have examined factors that regulate fission-fusion dynamics (FFD) in chimpanzee communities, such as receptive females, predation risks, and food availability. However, the effects of these factors vary between populations. In this study, we conducted focal animal observations of adult males in the M group in Kalinzu to examine the influence of male dominance rank, aggression from other males, the presence of females exhibiting maximum sexual swelling (MS), and fruit abundance on male tendencies of party attendance. We found that low-ranking males spent more time alone than other males when females with MS were absent. In contrast, when females with MS were present, males of all ranks showed a similar tendency of party attendance. We also found that the aggressive interactions increased with the number of males irrespective of the presence or absence of females with MS, and low-ranking males attracted aggression more frequently than higher-ranking males. These results suggest that low-ranking males frequently ranged alone to avoid aggression from other males unless they attended parties to seek mating opportunities. We conclude that low-ranking males have alternative tactics to balance the costs and benefits incurred or gained when attending parties.
多项研究探讨了调节黑猩猩群体中裂变-融合动态（FFD）的因素，如处于发情期的雌性、捕食风险和食物供应情况。然而，这些因素的影响在不同种群之间存在差异。在本研究中，我们对卡林祖M组的成年雄性进行了焦点动物观察，以考察雄性优势等级、来自其他雄性的攻击行为、出现最大性肿胀（MS）的雌性的存在以及果实丰度对雄性参与群体活动倾向的影响。我们发现，在没有出现MS的雌性时，地位较低的雄性比其他雄性独处的时间更多。相比之下，当出现MS的雌性在场时，各等级的雄性都表现出类似的参与群体活动的倾向。我们还发现，无论是否有出现MS的雌性，攻击性互动都随着雄性数量的增加而增加，并且地位较低的雄性比地位较高的雄性更容易受到攻击。这些结果表明，地位较低的雄性经常独自活动以避免来自其他雄性的攻击，除非它们参与群体活动以寻求交配机会。我们得出结论，地位较低的雄性有其他策略来平衡参与群体活动时产生或获得的成本和收益。
