The objective of this study was to describe the nocturnal behavior patterns of the interaction between mothers and their juvenile offspring at the beginning of the juvenile period in two dyads of free-ranging spider monkeys (Ateles geoffroyi). Based on direct field observation, we recorded six interaction behaviors between mothers and their juvenile offspring at nighttime and during the daylight period. The frequencies and proportions of each behavior recorded were analyzed for both conditions, and qualitative descriptions of each behavior were made. Observations revealed that the percentage of proximity in the dyads tended to increase at nighttime compared to the daylight period. In one of the dyads, we observed that the percentage of grooming also showed an upward tendency at nighttime compared to the daylight period. The dyads remained together to sleep during all 8 days of the study and were seen to seek arm-in-arm contact and to perform grooming behaviors. Our results suggest that mother–juvenile interaction at the onset of the juvenile period in spider monkeys may be characterized by greater proximity and social grooming behaviors, while the nocturnal observations suggest a strong attachment between mothers and their juveniles in this stage.

中文翻译：

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自由放养蜘蛛猴（Ateles geoffroyi）幼年期开始时的夜间母幼子互动：两例报告

本研究的目的是描述两个自由放养蜘蛛猴 (Ateles geoffroyi) 在幼年期开始时母亲与其幼年后代相互作用的夜间行为模式。基于现场直接观察，我们记录了母亲与幼年后代在夜间和白天的六种互动行为。对两种条件下记录的每种行为的频率和比例进行分析，并对每种行为进行定性描述。观察结果显示，与白天相比，二元组中的接近百分比在夜间往往会增加。在其中一个二元组中，我们观察到，与白天相比，夜间梳理的百分比也呈上升趋势。在所有 8 天的研究中，这对二人一直在一起睡觉，并被视为寻求手挽手接触并进行梳理行为。我们的研究结果表明，蜘蛛猴幼年期开始时的母幼互动可能以更接近和社交修饰行为为特征，而夜间观察表明，在这个阶段，母幼之间存在强烈的依恋。