Data for "It pays to follow the leader: metabolic cost of flight is lower for trailing birds in small groups"

Data in support of the research described by this abstract:Many bird species commonly aggregate in flocks for reasons ranging from predator defense to navigation. Available evidence suggests that certain types of flocks—the V and echelon formations of large birds—may provide a benefit that reduces the aerodynamic cost of flight, whereas cluster flocks typical of smaller birds may increase flight costs. However, metabolic flight costs have not been directly measured in any of these group flight contexts. Here, we measured the energetic benefits of flight in small groups of two or three birds and the requirements for realizing those benefits, using metabolic energy expenditure and flight position measurements from European Starlings flying in a wind tunnel. The starlings continuously varied their relative position during flights but adopted a V formation motif on average, with a modal spanwise and streamwise spacing of [0.81, 0.91] wingspans. As measured via CO2 production, flight costs for follower birds were significantly reduced compared to their individual solo flight benchmarks. However, followers with more positional variability with respect to leaders did less well, even increasing their costs above solo flight. Thus, we directly demonstrate energetic costs and benefits for group flight followers in an experimental context amenable to further investigation of the underlying aerodynamics, wake interactions, and bird characteristics that produce these metabolic effects.

本摘要所描述的研究支持的数据：众多鸟类物种出于防御捕食者、导航等多重原因通常成群结队飞行。现有证据表明，某些类型的鸟群——如大型鸟类的V形和斜排形编队——可能带来降低飞行气动成本的益处，而典型于小型鸟类的集群编队可能增加飞行成本。然而，在上述任何群飞情境中，均未直接测量过代谢飞行成本。本研究中，我们通过测量欧洲金丝雀在风洞中飞行时的代谢能量消耗和飞行位置，直接测量了小型两至三只鸟群飞行时的能量效益及其实现这些效益的要求。金丝雀在飞行过程中持续调整其相对位置，但平均而言，它们采取了V形编队模式，其横向和纵向间距在[0.81, 0.91]翼展范围内。通过二氧化碳排放量的测量，跟随者的飞行成本与它们的单独飞行基准相比显著降低。然而，相对于领飞者的位置变动较大的跟随者表现不佳，甚至其成本超过了单独飞行。因此，我们在一个适宜进一步研究底层空气动力学、尾流相互作用以及产生这些代谢效应的鸟类特性的实验情境中，直接展示了群飞跟随者的能量成本与效益。