Data from: Investigating variation in third-party intervention behavior during a fallow deer (Dama dama) rut

Pairwise contests are frequently disrupted by the intervention of third-party group members. However, little is known about whether an individual’s engagement in intervention behavior varies over time, or what factors might be associated with such variation. Using a hierarchical “hurdle” model with 2 levels, we investigated the conditions under which focal males: 1) would or would not engage in an intervention, and 2) varied the number of interventions per day they engaged in. The lower level of the model showed that the proportion of unique opponents per day (estimated from the overall number of mature males in the herd) that focal males competed with, and the number of interventions suffered by a focal male were associated with an increased probability that this individual would itself engage in third-party intervention behavior. At the upper level of the model, there was no association between these 2 variables and the rate at which individuals engaged in intervention behavior. The number of matings observed per day and aggression rate within the herd failed to contribute meaningfully to either level of the model. We also show that, although inconsistent over days and between years, some individuals displayed a greater propensity to intervene than others. The data from our study show that intervention behavior is more likely to occur as a result of individual directly experiencing aggressive behavior at a sufficiently high level, and not as a result of individuals monitoring aggressive or sexual activity in the wider social group.

成对争斗常因群体内第三方成员的介入而中断。然而，目前学界对个体介入第三方干预行为的频次是否随时间变化，以及哪些因素与该变化相关仍知之甚少。我们采用两层分层 hurdle模型（hierarchical hurdle model），探究了焦点雄性（focal males）的两类行为条件：1）是否会实施介入行为；2）每日介入行为的次数存在何种变化。模型的下层分析显示，焦点雄性每日竞争的独特对手占比（基于种群内成熟雄性总数量估算），以及焦点雄性自身遭受的介入行为次数，均与该个体实施第三方干预行为的概率提升呈显著关联。模型上层分析则表明，上述两个变量与个体实施干预行为的频次并无显著关联。每日观测到的交配次数与种群内的攻击率，均未对模型的两层分析产生有效贡献。此外我们还发现，尽管不同日期与年份间的介入行为存在波动，但部分个体相较于其他个体，展现出更高的干预倾向。本研究数据表明，第三方干预行为更易发生于个体自身遭受了足够高强度的攻击行为时，而非源于个体对更广社交群体内的攻击或交配活动进行监控。