ABSTRACT Capsule: An experiment in the field supports the hypothesis that Grey Partridges Perdix perdix purposely expose their first laid eggs in order to test the predation risk at their nest site. Aims: To test the hypothesis that female Grey Partridges leave first laid eggs uncovered to assess the predation risk at their chosen nesting site. Methods: Four area-independent experiments with artificial nests were used. Predation risk was estimated by daily nest failure rate. Generalized linear mixed-effects models were used in statistical analysis. Results: We found that Grey Partridge females could predict nest site safety. At nest sites where the first uncovered egg was depredated, there was a higher predation risk for the whole clutch. Conclusion: Our data statistically support the hypothesis that leaving the first egg uncovered serves to provide a more conspicuous bait for potential predators and could be a female tactic for better recognizing predation risk at a nesting site. Thus, if the first uncovered egg is depredated, the female may start a new clutch elsewhere without wasting investment in the clutch at a site under high predation risk.

中文翻译：

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灰鹧鸪筑巢初期不覆盖卵的防捕食功能：田间试验

摘要胶囊：现场的一项实验支持这样的假设，即灰鹧鸪Perdix perdix 故意暴露其第一次产下的蛋，以测试其巢穴的捕食风险。目的：为了检验雌性灰鹧鸪将第一次产下的蛋暴露在外的假设，以评估其所选筑巢地点的捕食风险。方法：使用人工巢穴进行四次区域独立实验。捕食风险是通过每天的巢失败率来估计的。广义线性混合效应模型用于统计分析。结果：我们发现灰鹧鸪雌性可以预测巢址安全。在第一个未发现的蛋被掠食的巢穴中，整个窝的捕食风险更高。结论：我们的数据在统计上支持这样的假设，即让第一个鸡蛋未被覆盖可以为潜在的捕食者提供更显眼的诱饵，并且可能是一种女性策略，可以更好地识别筑巢地点的捕食风险。因此，如果第一个未发现的卵被掠食，雌性可能会在其他地方开始新的繁殖，而不会在高捕食风险的地点浪费对繁殖的投资。