Display court ecology in male Albert’s Lyrebirds

Display courts are fundamental to the sexual displays of many species of bird; however, the ecology of display courts is poorly understood, representing an important gap in our understanding of the function and evolution of complex animal displays. Here, we describe the biophysical attributes (‘ecology’) of the display courts of male Albert’s Lyrebirds, a ground-dwelling rainforest species that performs a spectacular song and dance display on set courts, known as ‘display platforms’, that are composed of vines or fallen branches. Males rhythmically move these vegetative structures while singing, forming a unique ‘stage shaking’ component of their sexual display. We investigated whether display platforms differed from random locations within a male’s territory in terms of the number of vines or other vegetative structures, area of ground clearing, vegetation density, and canopy cover measurements. We primarily found that platforms had a larger number of vines or other vegetative structures. Platforms also tended to be in areas with more canopy openings. We suggest that platform features amplify the movement of the dancing male, and that male Albert’s Lyrebirds choose platforms in locations that increase their conspicuousness to female receivers.

求偶场（display court）是诸多鸟类性展示行为的核心基础；然而当前学界对求偶场的生态学特征仍缺乏充分认知，这一认知空白亦是我们理解复杂动物展示行为的功能与演化机制的关键短板。本研究针对艾伯氏琴鸟（Albert's Lyrebird）——一种栖息于雨林的地栖物种——的求偶场展开生物物理特征（即其「生态学」维度）的描述：该物种会在由藤蔓或枯木枝干构成的固定展示平台（display platform）上，完成兼具鸣唱与舞蹈的华丽展示行为。雄性个体在鸣唱过程中会规律性地移动这些植物结构，由此形成其性展示行为中独特的「平台震颤」环节。本研究对比分析了雄性领地内的随机点位与展示平台在藤蔓/其他植物结构数量、地面清理面积、植被密度以及冠层覆盖度等指标上的差异。核心发现为：展示平台拥有更多的藤蔓及其他植物结构，且多分布于冠层开口更丰富的区域。本研究推测，展示平台的结构特征能够放大起舞雄性的动作幅度，且艾伯氏琴鸟雄性会选择能提升自身对雌性接收者显眼程度的点位来搭建展示平台。