Resolution of a paradox: Hummingbird flight at high elevation does not come without a cost
Resolution of a paradox: Hummingbird flight at high elevation does not come without a cost
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DOI：
10.1073/pnas.0405260101
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发表时间：
2004-12-21
影响因子：
11.1
通讯作者：
McGuire, JA
中科院分区：
文献类型：
--
作者：
Altshuler, DL;Dudley, R;McGuire, JA
高空飞行对能量的要求很高，因为空气密度和氧气供应量同时减少。蜂鸟的盘旋飞行是动物运动中能量消耗最大的形式之一，但蜂鸟在整个美洲的高海拔地区仍然很丰富。两种机制增强了高海拔蜂鸟的空气动力学性能：在悬停期间增加机翼尺寸和机翼冲程幅度。空气的形态学、运动学和物理特性的这些变化如何结合联合收割机来影响飞越海拔高度时的空气动力需求？在这里，我们提出了43个安第斯蜂鸟物种的飞行性能的数据，以及76个分类群的多位点的分子遗传学，作为比较分析的历史框架。沿着4,000米的海拔样带，蜂鸟的身体质量系统地增加，对高海拔类群提出了进一步的空气动力学要求。然而，我们发现，悬停飞行的最低功率要求保持不变，相对于海拔高度，因为蜂鸟通过增加翅膀的大小和冲程振幅充分补偿。因此，尽管低气压环境带来了挑战，但高海拔蜂鸟的盘旋飞行能力并不受限制。其他飞行模式，包括垂直上升和快速向前飞行，对机械和能量的要求更高，因此我们还通过使用负载提升试验测试了蜂鸟可用的最大功率。与悬停相反，在不同高度上，多余的动力可用性大大降低，从而降低了更复杂飞行的生物力学潜力，如竞争和逃生机动。
Flight at high elevation is energetically demanding because of parallel reductions in air density and oxygen availability. The hovering flight of hummingbirds is one of the most energetically expensive forms of animal locomotion, but hummingbirds are nonetheless abundant at high elevations throughout the Americas. Two mechanisms enhance aerodynamic performance in high-elevation hummingbirds: increase in wing size and wing stroke amplitude during hovering. How do these changes in morphology, kinematics, and physical properties of air combine to influence the aerodynamic power requirements of flight across elevations? Here, we present data on the flight performance of 43 Andean hummingbird species as well as a 76-taxon multilocus molecular phylogeny that served as the historical framework for comparative analyses. Along a 4,000-m elevational transect, hummingbird body mass increased systematically, placing further aerodynamic demands on high-elevation taxa. However, we found that the minimum power requirements for hovering flight remain constant with respect to elevation because hummingbirds compensate sufficiently through increases in wing size and stroke amplitude. Thus, high-elevation hummingbirds are not limited in their capacity for hovering flight despite the challenges imposed by hypobaric environments. Other flight modes including vertical ascent and fast forward flight are more mechanically and energetically demanding, and we accordingly also tested for the maximum power available to hummingbirds by using a load-lifting assay. In contrast to hovering, excess power availability decreased substantially across elevations, thereby reducing the biomechanical potential for more complex flight such as competitive and escape maneuvers.