Data from: Integrating morphology and kinematics in the scaling of hummingbird hovering metabolic rate and efficiency

Wing kinematics and morphology are influential upon the aerodynamics of flight. However, there is a lack of studies linking these variables to metabolic costs, particularly in the context of morphological adaptation to body size. Furthermore, the conversion efficiency from chemical energy into movement by the muscles (mechanochemical efficiency) scales with mass in terrestrial quadrupeds, but this scaling relationship has not been demonstrated within flying vertebrates. Positive scaling of efficiency with body size may reduce the metabolic costs of flight for relatively larger species. Here, we assembled a dataset of morphological, kinematic, and metabolic data on hovering hummingbirds to explore the influence of wing morphology, efficiency, and mass on hovering metabolic rate (HMR). We hypothesize that HMR would decline with increasing wing size, after accounting for mass. Furthermore, we hypothesize that efficiency will increase with mass, similarly to other forms of locomotion. We do not find a relationship between relative wing size and HMR, and instead find that the cost of each wingbeat increases hyperallometrically while wingbeat frequency declines with increasing mass. This suggests that increasing wing size is metabolically favourable over cycle frequency with increasing mass. Further benefits are offered to larger hummingbirds due to the positive scaling of efficiency.

翼运动学（wing kinematics）与翼形态学特征对飞行空气动力学性能具有显著影响。然而，当前仍缺乏将这些变量与代谢成本相关联的研究，尤其是在针对体型的形态适应性研究背景下。此外，陆生四足动物的肌肉将化学能转化为运动的转换效率，即机械化学效率（mechanochemical efficiency），会随体重发生缩放，但这种缩放关系尚未在飞行脊椎动物中得到证实。效率随体型正向缩放，或可降低相对较大物种的飞行代谢成本。本研究收集了悬停蜂鸟的形态学、运动学及代谢数据，以探究翼形态、转换效率与体重对悬停代谢率（hovering metabolic rate, HMR）的影响。我们提出假设：在控制体重变量的前提下，悬停代谢率会随翼尺寸的增大而降低。此外，我们假设转换效率会随体重增加而提升，这与其他运动形式的规律一致。本研究未发现相对翼尺寸与悬停代谢率之间存在关联，反而观察到：随着体重增加，单次振翅的代谢成本呈超异速生长增长，而振翅频率则随之降低。这表明，随着体重增加，相较于振翅频率，增大翼尺寸在代谢层面更为有利。由于转换效率随体型正向缩放，体型更大的蜂鸟还可获得额外的代谢益处。