Chai P, Altshuler D L, Stephens D B, Dillon M E
Department of Zoology, University of Texas, Austin, Texas 78712-1064.
Physiol Biochem Zool. 1999 Mar-Apr;72(2):145-55. doi: 10.1086/316652.
Hovering and fast forward flapping represent two strenuous types of flight that differ in aerodynamic power requirement. Maximal capabilities of ruby-throated hummingbirds (Archilochus colubris) in hovering and forward flight were compared under varying body mass and wing area. The capability to hover in low-density gas mixtures was adversely affected by body mass, whereas the capability to fly in a wind tunnel did not show any adverse mass effect. Molting birds that lost primary flight feathers and reduced wing area also displayed mass loss and loss of aerodynamic power and flight speed. This suggests that maximal flight speed is insensitive to short-term perturbations of body mass but that molting is stressful and reduces the birds' speed and capacity for chase and escape. Hummingbirds' flight behavior in confined space was also investigated. Birds reduced their speeds flying through a narrow tube to approximately one-fifth of that in the wind tunnel and did not display differences under varying body mass and wing area. Hence, performance in the flight tube was submaximal and did not correlate with performance variation in the wind tunnel. For ruby-throated hummingbirds, both maximal mass-specific aerodynamic power derived from hovering performance in low-density air media and maximal flight velocity measured in the wind tunnel were invariant with body mass.
悬停和快速向前扑动是两种剧烈的飞行方式，它们在空气动力功率需求方面存在差异。在不同体重和翼面积条件下，对红玉喉北蜂鸟（Archilochus colubris）的悬停和向前飞行的最大能力进行了比较。在低密度气体混合物中悬停的能力受到体重的不利影响，而在风洞中飞行的能力未显示出任何不利的体重效应。正在换羽的鸟类失去了初级飞羽且翼面积减小，同时也出现了体重减轻以及空气动力功率和飞行速度的下降。这表明最大飞行速度对体重的短期波动不敏感，但换羽是有压力的，会降低鸟类的速度以及追逐和逃避能力。还对蜂鸟在受限空间中的飞行行为进行了研究。鸟类在通过狭窄管道飞行时将速度降低到风洞飞行速度的约五分之一，并且在不同体重和翼面积条件下未表现出差异。因此，在飞行管道中的表现未达到最大值且与风洞中的表现变化无关。对于红玉喉北蜂鸟而言，在低密度空气介质中由悬停表现得出的最大质量比空气动力功率以及在风洞中测得的最大飞行速度均与体重无关。
