Abstract

Predation risk is among the most fundamental selection pressures, making anti-predation behavior a highly adaptive trait. Vigilance and escape are two important aspects of anti-predation behavior and have received considerable attention for decades. However, the relationship between them remains largely unexplored, and our knowledge on the diel patterns of these behaviors is also limited. In the present study, we measured various types of vigilance and escape behavior in Daurian ground squirrel (Spermophilus dauricus), to assess the function of vigilance in promoting detection and escape. We also explored the diel patterns of these anti-predation behaviors using comparisons among three periods within a day (morning, noon and evening). Total duration of vigilance was not closely associated with flight initiation distance, alert distance or buffer distance. However, duration of quadrupedal vigilance was negatively related to flight initiation distance, while positively related to alert distance and buffer distance. Alert distance was also negatively associated with duration of standing scan. These suggested that more vigilant individuals did not flee sooner as usually expected, and highlighted the necessity of separately considering the anti-predation function of various components of vigilance. A significant diel pattern was detected, with ground squirrels spending more time on energetically expensive vigilance (standing scan) and fleeing sooner (with longer flight initiation distance) at noon. Such a temporal pattern was more likely to be driven by the temporal changes in energetic status and balance between energy intake and safety thereof, rather than temporal changes in predation risk, competitors or detection ability.

Significance statement

Although vigilance and escape behavior have been frequently studied for decades, their relationship is rarely explored and it remains unclear whether a more vigilant individual would also flee sooner. In this study, we explored the relationship between individual vigilance level and flight initiation distance in a ground squirrel. We found that duration of quadrupedal vigilance, rather than total duration of vigilance, is significantly related to flight initiation distance. Contrary to expectations, individuals spending more time on quadrupedal vigilance tended to flee later, although they generally detected predators earlier. We also found that compared to the morning and evening, squirrels were more vigilant and fled sooner at noon, possibly due the temporal change in individual energetic status. Our results suggest that the anti-predation function of vigilance deserves reconsideration, and emphasize the importance of splitting vigilance into multiple components.

中文翻译：

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地松鼠反捕食行为的昼夜变异及警惕与逃跑的关系

摘要

捕食风险是最基本的选择压力之一，使反捕食行为成为一种高度适应性的特征。警惕和逃避是反捕食行为的两个重要方面，几十年来一直受到相当多的关注。然而，它们之间的关系在很大程度上仍未被探索，我们对这些行为的模式的了解也很有限。在本研究中，我们测量了达里安地松鼠 ( Spermophilus dauricus ) 的各种警戒和逃跑行为。)，以评估警觉在促进侦查和逃跑中的作用。我们还通过一天内三个时期（早上、中午和晚上）的比较来探索这些反捕食行为的昼夜模式。警惕的总持续时间与飞行起始距离、警戒距离或缓冲距离没有密切相关。然而，四足警戒持续时间与飞行起始距离呈负相关，而与警戒距离和缓冲距离呈正相关。警戒距离也与站立扫描的持续时间呈负相关。这些表明，警惕性更高的个体并没有像通常预期的那样更快地逃跑，并强调了分别考虑警惕性各个组成部分的反捕食功能的必要性。检测到显着的 diel 模式，地松鼠花费更多时间在精力充沛的警惕（站立扫描）上，并在中午更快地逃离（飞行起始距离更长）。这种时间模式更可能是由能量状态的时间变化以及能量摄入与其安全性之间的平衡所驱动，而不是捕食风险、竞争对手或检测能力的时间变化。

意义陈述

尽管几十年来经常研究警惕和逃避行为，但很少有人探讨它们之间的关系，而且尚不清楚一个更警惕的人是否也会更快地逃离。在这项研究中，我们探讨了地松鼠个体警觉水平与飞行起始距离之间的关系。我们发现四足警戒的持续时间，而不是警戒的总持续时间，与飞行起始距离显着相关。与预期相反，花更多时间在四足动物警戒上的个体往往会较晚逃离，尽管他们通常更早发现捕食者。我们还发现，与早晚相比，松鼠在中午更加警觉，逃得更快，这可能是由于个体能量状态的时间变化。