Stevens Martin, Troscianko Jolyon, Wilson-Aggarwal Jared K, Spottiswoode Claire N
Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
Nat Ecol Evol. 2017 Sep;1(9):1325-1333. doi: 10.1038/s41559-017-0256-x. Epub 2017 Jul 31.
Animal camouflage is a longstanding example of adaptation. Much research has tested how camouflage prevents detection and recognition, largely focusing on changes to an animal's own appearance over evolution. However, animals could also substantially alter their camouflage by behaviourally choosing appropriate substrates. Recent studies suggest that individuals from several animal taxa could select backgrounds or positions to improve concealment. Here, we test whether individual wild animals choose backgrounds in complex environments, and whether this improves camouflage against predator vision. We studied nest site selection by nine species of ground-nesting birds (nightjars, plovers and coursers) in Zambia, and used image analysis and vision modeling to quantify egg and plumage camouflage to predator vision. Individual birds chose backgrounds that enhanced their camouflage, being better matched to their chosen backgrounds than to other potential backgrounds with respect to multiple aspects of camouflage. This occurred at all three spatial scales tested (a few cm and five meters from the nest, and compared to other sites chosen by conspecifics), and was the case for the eggs of all bird groups studied, and for adult nightjar plumage. Thus, individual wild animals improve their camouflage through active background choice, with choices highly refined across multiple spatial scales.
动物伪装是适应性的一个长期例证。许多研究测试了伪装如何防止被发现和识别，主要聚焦于动物自身外观在进化过程中的变化。然而，动物也可以通过行为上选择合适的基质来显著改变它们的伪装。最近的研究表明，来自几个动物类群的个体可以选择背景或位置来提高隐蔽性。在这里，我们测试个体野生动物是否会在复杂环境中选择背景，以及这是否能增强对捕食者视觉的伪装效果。我们研究了赞比亚9种地栖鸟类（夜鹰、鸻和走鸻）的筑巢地点选择，并使用图像分析和视觉建模来量化卵和羽毛对捕食者视觉的伪装效果。个体鸟类选择的背景增强了它们的伪装效果，在伪装的多个方面，它们与所选背景的匹配度高于与其他潜在背景的匹配度。这种情况在所有测试的三个空间尺度上都出现了（距离巢穴几厘米和五米处，以及与同种个体选择的其他地点相比），并且在所研究的所有鸟类群体的卵以及成年夜鹰的羽毛上都是如此。因此，个体野生动物通过积极选择背景来改善它们的伪装，并且这些选择在多个空间尺度上都经过了高度优化。
