Interspecific variation in the structural properties of flight feathers in birds indicates adaptation to flight requirements and habitat

1. The functional significance of intra- and interspecific structural variations in the flight feathers of birds is poorly understood. Here, a phylogenetic comparative analysis of four structural features (rachis width, barb and barbule density and porosity) of proximal and distal primary feathers of 137 European bird species was conducted. 2. Flight type (flapping and soaring, flapping and gliding, continuous flapping or passerine type), habitat (terrestrial, riparian or aquatic), wing characteristics (wing area, S and aspect ratio, AR) and moult strategy were all found to affect feather structure to some extent. Species characterized by low wing-beat frequency flight (soaring and gliding) have broader feather rachises (shafts) and feather vanes with lower barb density than birds associated with more active flapping modes of flight. However, the effect of flying mode on rachis width disappeared after controlling for S and AR, suggesting that rachis width is primarily determined by wing...

1. 鸟类飞羽种内与种间结构变异的功能意义迄今仍未得到充分阐释。本研究针对137种欧洲鸟类的初级飞羽近端及远端区段的4项结构特征——羽轴宽度（rachis width）、羽枝密度、羽小枝密度与孔隙度——开展了系统发育比较分析。
2. 飞行类型（振翅翱翔型、振翅滑翔型、持续振翅型或雀形目飞行模式）、栖息生境（陆生、河岸生境或水生环境）、翼部特征（翼面积S与展弦比AR）以及换羽策略，均对羽毛结构存在不同程度的影响。相较于依赖高频振翅飞行的鸟类，低振翅频率飞行类群（翱翔与滑翔型）的物种，其飞羽羽轴更为宽阔，且羽枝密度更低。不过，在控制翼面积与展弦比的影响后，飞行模式对羽轴宽度的影响效应便不复存在，这表明羽轴宽度主要由翼部……