Wooddell Lauren J, Kaburu Stefano Sk, Suomi Stephen J, Dettmer Amanda M
Eunice Kennedy Shriver National Institute for Child Health and Human Development, NIH, Poolesville, Maryland;, Email:
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California.
J Am Assoc Lab Anim Sci. 2017 May 1;56(3):260-268.
Rhesus macaques (Macaca mulatta) are gregarious primates that form despotic societies characterized by frequent and intense aggression. Within long-term social groups, demographic changes may influence hierarchical stability, potentially resulting in conflict and violently abrupt hierarchical changes. This conflict can result in serious implications for animal welfare, and thus, predictive tools would be invaluable to captive managers in determining social instabilities. Using the method Elo-rating to track rank changes and dominance stability, we predicted that demographic changes to a population of semi-free ranging rhesus macaques would result in changes in hierarchical stability. Over a 3 y period, dominance data were recorded on all troop members to track the hierarchy. Throughout the 3 y, significant changes occurred to the population (mainly due to health and colony management reasons; no changes specifically occurred for this study) including permanent removal of a large group of natal males, temporary and permanent removal of top-ranking females, and depositions of top-ranking families. Our retrospective study suggests that removing natal males was beneficial in promoting overall troop stability (that is, stability of dominance relationships), although remaining males opportunistically attempted to increase in rank, perhaps due to limited competition. Our results also suggest that removing top-ranking females, even temporarily, destabilized dominance relationships; consequently adjacently ranked females opportunistically increased in Elo-rating, both before and after the depositions of the α families. Thus, these challenges to the established hierarchy can be predicted by increases in Elo-rating within the β families after demographic changes to the α families. Our results suggest that the presence of natal males and the removal of top-ranking females should be minimized to maintain stable dominance relationships. In addition, longitudinal data reflecting dominance ranks, collected by using Elo-rating, may help managers of captive colonies in predicting dominance instabilities before they occur.
恒河猴（猕猴）是群居性灵长类动物，它们形成了以频繁且激烈的攻击行为为特征的专制社会。在长期的社会群体中，人口结构变化可能会影响等级制度的稳定性，从而可能导致冲突和等级制度的剧烈突然变化。这种冲突可能会对动物福利产生严重影响，因此，预测工具对于圈养管理者确定社会不稳定因素将具有极高价值。使用Elo评分法来追踪等级变化和优势稳定性，我们预测半散养恒河猴种群的人口结构变化将导致等级制度稳定性的改变。在3年的时间里，记录了所有猴群成员的优势数据以追踪等级制度。在这3年中，种群发生了重大变化（主要是由于健康和群体管理原因；本研究没有特别发生的变化），包括一大群出生时就在群体中的雄性被永久移除、顶级雌性的临时和永久移除，以及顶级家族的地位下降。我们的回顾性研究表明，移除出生时就在群体中的雄性有利于促进整个猴群的稳定性（即优势关系的稳定性），尽管剩余的雄性会伺机试图提升等级，这可能是由于竞争有限。我们的结果还表明，即使是暂时移除顶级雌性也会破坏优势关系的稳定性；因此，在α家族地位下降之前和之后，相邻等级的雌性都会伺机提高Elo评分。因此，在α家族人口结构发生变化后，β家族内Elo评分的增加可以预测对既定等级制度的这些挑战。我们的结果表明，应尽量减少出生时就在群体中的雄性的存在以及顶级雌性的移除，以维持稳定的优势关系。此外，通过使用Elo评分收集的反映优势等级的纵向数据，可能有助于圈养群体的管理者在优势不稳定发生之前进行预测。
