Agostini Nicolantonio, Panuccio Michele, Pasquaretta Cristian
MEDRAPTORS (Mediterranean Raptor Migration Network), Via Mario Fioretti 18, 00152 Rome, Italy.
University of Pavia, Department of Earth and Environmental Sciences, Via Ferrata 9, 27100 Pavia (PV) , Italy.
Curr Zool. 2015 Dec;61(6):951-958. doi: 10.1093/czoolo/61.6.951. Epub 2015 Dec 1.
Raptors primarily use soaring-gliding flight which exploits thermals and ridge lifts over land to reduce energetic costs. However during migration, these birds often have to cross water surfaces where thermal currents are weak; during these times, birds mainly use flapping (powered) flight which increases energy consumption and mortality risk. As a result, some species have evolved strategies to reduce the amount of time spent over water by taking extensive detours over land. In this paper, we conducted a meta-analysis of water-crossing tendencies in Afro-Palearctic migrating raptors in relation to their morphology, their flight performance, and their phylogenetic relationships. In particular, we considered the aspect ratio (calculated as the wing span squared divided by wing area), the energetic cost of powered flight, and the maximum water crossing length regularly performed by adult birds. Our results suggest that energy consumption during powered flight predominately affects the ability of raptors to fly over water surfaces.
猛禽主要采用翱翔-滑翔飞行方式，利用陆地上的上升热气流和山脊上升气流来降低能量消耗。然而在迁徙过程中，这些鸟类常常需要穿越热气流较弱的水面；在此期间，鸟类主要使用扑翼（动力）飞行，这会增加能量消耗和死亡风险。因此，一些物种进化出了通过在陆地上进行大幅度迂回以减少在水面停留时间的策略。在本文中，我们对非洲-古北界迁徙猛禽的越水倾向与其形态、飞行性能以及系统发育关系进行了荟萃分析。具体而言，我们考虑了展弦比（计算方法为翼展平方除以翼面积）、动力飞行的能量消耗以及成年鸟类通常能跨越的最大水面长度。我们的结果表明，动力飞行期间的能量消耗主要影响猛禽飞越水面的能力。
