KleinHeerenbrink Marco, Hedenström Anders
Department of Biology , Lund University , Sölvegatan 37, 223 62 Lund , Sweden.
Interface Focus. 2017 Feb 6;7(1):20160081. doi: 10.1098/rsfs.2016.0081.
To maintain the quality of the feathers, birds regularly undergo moult. It is widely accepted that moult affects flight performance, but the specific aerodynamic consequences have received relatively little attention. Here we measured the components of aerodynamic drag from the wake behind a gliding jackdaw () at different stages of its natural wing moult. We found that span efficiency was reduced (lift induced drag increased) and the wing profile drag coefficient was increased. Both effects best correlated with the corresponding reduction in spanwise camber. The negative effects are partially mitigated by adjustments of wing posture to minimize gaps in the wing, and by weight loss to reduce wing loading. By studying the aerodynamic consequences of moult, we can refine our understanding of the emergence of various moulting strategies found among birds.
为了保持羽毛的质量，鸟类会定期换羽。人们普遍认为换羽会影响飞行性能，但具体的空气动力学后果却相对较少受到关注。在这里，我们测量了一只正在自然换羽不同阶段的滑翔寒鸦身后尾流中的空气动力学阻力成分。我们发现展向效率降低（诱导阻力增加），且翼型阻力系数增加。这两种效应都与展向弯度相应减小最为相关。通过调整翅膀姿态以尽量减小翅膀间隙以及减轻体重以降低翼载荷，这些负面影响会得到部分缓解。通过研究换羽的空气动力学后果，我们可以加深对鸟类中发现的各种换羽策略出现原因的理解。
