Meeting Abstract
Wings are the primary aerodynamic surface for volant taxa, but the consequences of wing degradation for flight performance are unclear. We artificially introduced wing tip deficits in Anna’s Hummingbirds by reducing the length of the four outermost primary wing feathers. Group 1 birds were measured throughout three consecutive sessions: a control, reduction of 15% of primary feather lengths in one wing only, and reduction of 15% of primary feather lengths in both wings. Group 2 birds were measured twice, once during control sessions and following a reduction in primary feather length by 7.5% for both wings. We used respirometry to determine flight metabolic rate, particle image velocimetry (PIV) to estimate wingtip circulation, and high-speed videography for wing and body kinematics analysis for birds flying within a variable-speed wind tunnel at 0, 6 and 12 m/s. Rates of oxygen uptake substantially increased in Group 1 birds with asymmetric wingtip ablation compared with controls, but only slightly further increased when the wingtip deficit was introduced to the contralateral wing. In Group 2 birds, effects of wingtip ablation on bird energetics were significant but slight. PIV measurements indicated increased circulation on ablated wings. Morphologically associated bilateral asymmetry of the wing motions alters flight performance and incurs considerable metabolic cost, suggesting selective benefits to maintenance of wing symmetry.
