Data from: Behaviorally-induced camouflage: a new mechanism of avian egg protection

When animals potentially occupy diverse microhabitats, how can camouflage be achieved? Here we combine descriptive and experimental methods to uncover a novel form of phenotypic plasticity in the camouflage of bird eggs that may be present in other avian taxa. Soil from the bare substrate adheres to the blue-footed booby´s (Sula nebouxii) pale eggs, which parents manipulate both under and on top of their webs. Analysis of digital images confirmed that dirtiness increases progressively during the first 16 days of the incubation period, making eggs more similar to the nest substrate. Observations of 3,668 single-egg clutches showed that probability of egg loss declines progressively over the same timeframe and then remains low for the rest of the 41-day incubation period. An experiment showed that when chicken eggs are soiled and exposed in artificial booby nests, they are less likely to be taken by Heermann´s gulls (Larus heermanni) than clean eggs.

当动物可栖息于多样微生境时，该如何实现伪装？本研究结合描述性与实验性方法，揭示了鸟类卵伪装中一种全新的表型可塑性（phenotypic plasticity）形式，该机制可能也存在于其他鸟类类群中。裸露基质上的泥土会粘附在蓝脚鲣鸟（Sula nebouxii）的浅色卵表面，而亲鸟会在巢垫下方与上方对卵进行打理。对数码图像的分析证实，在孵化期的前16天内，卵表面的脏污程度会逐渐增加，使卵与巢基质的外观愈发接近。对3668个单卵窝的观测结果显示，卵的丢失概率在上述16天内逐渐降低，随后在整个41天孵化期的剩余阶段均维持在较低水平。一项实验表明，将沾有泥土的鸡卵放置在人工鲣鸟巢中时，其被赫氏鸥（Larus heermanni）捕食的概率要低于干净的鸡卵。