The ability to recognize mates, kin, offspring and neighbors by their individually distinctive traits—individual recognition (IR)—is widespread in animals. Much work has investigated IR from the perspective of the recognizer, but less is known about the extent to which signals have evolved to facilitate IR. To explore this, one approach is to compare putative identity signals among species that differ in life history and extent of IR. In Common Murres (Uria aalge), a colonially breeding seabird, the eggs of individual females are remarkably variable in terms of color and pattern (maculation). Common Murres also appear to recognize their own eggs, leading to the hypothesis that variable egg phenotypes evolved to promote recognizability. However, we lack a quantitative assessment of the egg pattern information in Common Murres and their close relatives. Here, we analyzed images of eggs laid by four alcid species: Common Murres, Thick-billed Murres (Uria lomvia), Razorbills (Alca torda) and Dovekies (Alle alle). We extracted pattern measures believed to be relevant to bird vision and calculated Beecher's information statistic (H_s), which allowed us to compare the amount of identity information contained in each species’ egg patterns. Murres, which nest in dense colonies and can recognize their own eggs, have egg patterns with a relatively large amount of identity information compared to Razorbills and Dovekies. Egg recognition has not been demonstrated in Razorbills and Dovekies, whose colonies are less dense. Our results are consistent with the hypothesis that complex patterns of Murre eggs may have evolved to increase individual recognizability.

中文翻译：

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作为殖民地海鸟身份信号的鸡蛋图案：四种酸性物种的比较

通过个体独特的特征——个体识别（IR）——来识别配偶、亲属、后代和邻居的能力在动物中很普遍。许多工作从识别器的角度研究了 IR，但对信号进化到促进 IR 的程度知之甚少。为了探索这一点，一种方法是比较生活史和 IR 范围不同的物种之间的假定身份信号。在常见的 Murres ( Uria aalge)，一种在殖民地繁殖的海鸟，个体雌性的卵在颜色和图案（斑点）方面差异很大。Common Murres 似乎也能识别自己的卵子，这导致了这样一种假设，即可变的卵子表型进化以促进可识别性。然而，我们缺乏对 Common Murres 及其近亲的卵形信息的定量评估。在这里，我们分析了四种碱性物种产卵的图像：常见的 Murres、厚嘴 Murres ( Uria lomvia )、Razorbills (Alca torda ) 和 Dovekies ( Alle alle )。我们提取了被认为与鸟类视觉相关的模式度量，并计算了 Beecher 的信息统计量（H _s)，这使我们能够比较每个物种的卵模式中包含的身份信息量。Murres在密集的菌落中筑巢并且可以识别自己的蛋，与Razrbills和Dovekies相比，它们的蛋图案具有相对大量的身份信息。Razorbills 和 Dovekies 的蛋识别尚未得到证实，它们的菌落密度较低。我们的结果与 Murre 蛋的复杂模式可能已经进化以增加个体可识别性的假设一致。