KleinHeerenbrink Marco, Johansson L Christoffer, Hedenström Anders
Department of Biology, Lund University, Lund, Sweden
Department of Zoology, University of Oxford, Oxford, UK.
J R Soc Interface. 2017 May;14(130). doi: 10.1098/rsif.2017.0099.
Slotted wing tips of birds are commonly considered an adaptation to improve soaring performance, despite their presence in species that neither soar nor glide. We used particle image velocimetry to measure the airflow around the slotted wing tip of a jackdaw () as well as in its wake during unrestrained flight in a wind tunnel. The separated primary feathers produce individual wakes, confirming a multi-slotted function, in both gliding and flapping flight. The resulting multi-cored wingtip vortex represents a spreading of vorticity, which has previously been suggested as indicative of increased aerodynamic efficiency. Considering benefits of the slotted wing tips that are specific to flapping flight combined with the wide phylogenetic occurrence of this configuration, we propose the hypothesis that slotted wings evolved initially to improve performance in powered flight.
鸟类的开缝翼尖通常被认为是一种用于提高翱翔性能的适应性特征，尽管在既不翱翔也不滑翔的物种中也存在这种特征。我们使用粒子图像测速技术，在风洞中对寒鸦（）自由飞行时其开缝翼尖周围以及尾流中的气流进行了测量。分离的初级飞羽产生了各自的尾流，这在滑翔和扑翼飞行中都证实了其多开缝功能。由此产生的多核心翼尖涡流代表了涡度的扩散，此前曾有人提出这表明空气动力学效率有所提高。考虑到开缝翼尖在扑翼飞行中的特定优势以及这种结构在广泛的系统发育中的出现情况，我们提出一个假设，即开缝翼最初进化是为了提高动力飞行的性能。
