Escape theory has been exceptionally successful in conceptualizing and accurately predicting effects of numerous factors that affect predation risk and explaining variation in flight initiation distance (FID; predator–prey distance when escape begins). Less explored is the relative orientation of an approaching predator, prey, and its eventual refuge. The relationship between an approaching threat and its refuge can be expressed as an angle we call the “interpath angle” or “Φ,” which describes the angle between the paths of predator and prey to the prey’s refuge and thus expresses the degree to which prey must run toward an approaching predator. In general, we might expect that prey would escape at greater distances if they must flee toward a predator to reach its burrow. The “race for life” model makes formal predictions about how Φ should affect FID. We evaluated the model by studying escape decisions in yellow-bellied marmots Marmota flaviventer, a species which flees to burrows. We found support for some of the model’s predictions, yet the relationship between Φ and FID was less clear. Marmots may not assess Φ in a continuous fashion; but we found that binning angle into 4 45° bins explained a similar amount of variation as models that analyzed angle continuously. Future studies of Φ, especially those that focus on how different species perceive relative orientation, will likely enhance our understanding of its importance in flight decisions.

中文翻译：

---

对逃避行为的实证研究发现，对生命竞赛模型的支持有好有坏

逃逸理论在概念化和准确预测影响捕食风险的众多因素的影响方面取得了巨大成功，并解释了飞行起始距离（FID；逃逸开始时捕食者与猎物的距离）的变化。较少研究的是接近的捕食者、猎物及其最终避难所的相对方向。接近的威胁与其避难所之间的关系可以表示为一个角度，我们称之为“路径间角”或“Φ”，它描述了捕食者和猎物到猎物避难所的路径之间的角度，从而表达了猎物的程度必须跑向接近的掠食者。一般来说，如果猎物必须逃向捕食者以到达其洞穴，我们可能会预期猎物会逃得更远。“生命竞赛”模型对 Φ 应如何影响 FID 进行了正式预测。我们通过研究黄腹土拨鼠 Marmota flaviventer（一种逃往洞穴的物种）的逃逸决策来评估该模型。我们发现模型的一些预测得到了支持，但 Φ 和 FID 之间的关系不太清楚。土拨鼠可能不会以连续的方式评估 Φ；但我们发现将角度分入 4 个 45° 分箱可以解释与连续分析角度的模型类似的变化量。未来对 Φ 的研究，尤其是那些关注不同物种如何感知相对方向的研究，可能会增强我们对其在飞行决策中重要性的理解。