Increased Egg–Nest Visual Contrast Does Not Induce Egg Ejection in the Eastern Phoebe (Sayornis phoebe), an Accepter Host of the Brood Parasitic Brown-Headed Cowbird (Molothrus ater)
Increased Egg–Nest Visual Contrast Does Not Induce Egg Ejection in the Eastern Phoebe (Sayornis phoebe), an Accepter Host of the Brood Parasitic Brown-Headed Cowbird (Molothrus ater)
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增加卵巢视觉对比度不会导致东部菲比（Sayornis phoebe）（巢寄生棕头牛鹂（Molothrus ater）的接受宿主）的卵排出
DOI：
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发表时间：
2019
影响因子：
1.4
通讯作者：
M. Hauber
中科院分区：
文献类型：
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作者：
Zachary Aidala;B. Strausberger;M. Hauber
专性育雏寄生鸟的宿主可以通过拒绝外来卵来抵消寄生成本。与绝大多数棕头牛鹂 (Molothrus ater) 的寄主一样，东部楠鹬 (Sayornis phoebe) 接受牛鹂寄生，反而会产生巨大的健康成本。我们研究了对棕头牛鹂蛋的接受是否可能是由于东部楠鸟巢中的隐匿性而缺乏识别来介导的，以及是否可以通过操纵蛋巢视觉对比度来诱导蛋拒绝行为，作为人工寄生实验中促进寄生蛋检测的一种手段。我们发现，与楠木蛋相比，棕头牛鹂蛋与天然巢衬的视觉对比度显着较低，但没有显着降低，这表明牛鹂蛋在东部楠木倾向于筑巢的天然或人工覆盖的壁架的低环境光环境中可能是神秘的。我们还发现，尽管在我们的治疗中成功地增加了卵巢视觉对比度，但东方菲比并没有排斥模型寄生卵。我们的研究结果与之前的研究结果一致，表明增加蛋巢视觉对比度并不会增加禽类寄生虫宿主对寄生卵的辨别力和排斥力。由于感官模型显示，东部菲比斯预计能够在视觉上感知自然和实验性寄生事件，因此这些宿主被认为缺乏拒绝巢穴中不同卵所需的认知灵活性。未来的工作应该确定是否可以通过使用更多样化的人造卵刺激来使该受体物种和其他受体物种拒绝寄生。
Hosts of obligate brood parasitic birds can offset the costs of parasitism by rejecting foreign eggs. Like the vast majority of brown-headed cowbird (Molothrus ater) hosts, the eastern phoebe (Sayornis phoebe) paradoxically incurs substantial fitness costs by accepting cowbird parasitism. We investigated whether acceptance of brown-headed cowbird eggs may be mediated via lack of recognition due to crypsis in eastern phoebe nests, and whether egg-rejection behavior could be induced by manipulating egg–nest visual contrast as a means of facilitating parasitic egg detection in an artificial parasitism experiment. We found that brown-headed cowbird eggs have significantly lower achromatic, but not chromatic, visual contrast against the natural nest lining relative to phoebe eggs, suggesting that cowbird eggs may be cryptic in the low ambient light environments of natural or artificial covered ledges where eastern phoebes tend to nest. We also found that despite successfully increasing egg–nest visual contrast in our treatment, eastern phoebes did not reject model parasitic eggs. Our findings are consistent with previous work showing that increased egg–nest visual contrasts do not increase parasitic egg discriminability and rejection in hosts of avian brood parasites. Because sensory modeling showed that eastern phoebes were predicted to be able to visually perceive natural and experimental parasitism events, these hosts are suggested to lack the cognitive flexibility necessary to reject dissimilar eggs in their nests. Future work should determine whether this and other accepter species can be made to reject parasitism by using a more diverse array of artificial egg stimuli.