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）与形态学特征对飞行空气动力学具有显著影响。然而，目前鲜有研究将这些变量与代谢成本关联起来，尤其是在形态特征适配体型的研究背景下。此外，陆生四足动物中，肌肉将化学能转化为运动的效率（肌肉化学机械转化效率，mechanochemical efficiency）会随体重发生尺度缩放，但这一尺度关系尚未在飞行脊椎动物中得到证实。效率随体型正向尺度缩放，或可降低体型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、运动学及代谢学数据集，以探究翼形态、效率与体重对悬停代谢率（hovering metabolic rate, HMR）的影响。我们提出假设：在控制体重变量后，悬停代谢率会随翼尺寸增大而降低；此外，与其他运动形式类似，肌肉化学机械转化效率会随体重升高而提升。本研究未发现相对翼尺寸与悬停代谢率间存在关联；反而观察到，随着体重增大，单次振翅的代谢成本呈超异速增长趋势，而振翅频率则随之降低。这表明，随着体重增加，增大翼尺寸相比提升振翅频率更具代谢优势。而效率正向尺度缩放的特性，进一步为体型更大的蜂鸟带来了额外代谢收益。