Multi-cored vortices support function of slotted wing tips of birds in gliding and flapping flight.
Slotted wing tips of birds are commonly considered an adaptation to improve soaring performance, despite their presence in species that neither soar nor glide. We used particle image velocimetry to measure the airflow around the slotted wing tip of a jackdaw (Corvus monedula) as well as in its wake during unrestrained flight in a wind tunnel. The separated primary feathers produce individual wakes, confirming a multi-slotted function, in both gliding and flapping flight. The resulting multi-cored wingtip vortex represents a spreading of vorticity, which has previously been suggested as indicative of increased aerodynamic efficiency. Considering benefits of the slotted wing tips that are specific to flapping flight combined with the wide phylogenetic occurrence of this configuration, we propose the hypothesis that slotted wings evolved initially to improve performance in powered flight.
['KleinHeerenbrink|Marco|M|0000-0001-8172-8121', 'Johansson|L Christoffer|LC|0000-0002-1851-3635', 'Hedenström|Anders|A|0000-0002-1757-0945']
D000392:Air Movements D000818:Animals D001696:Biomechanical Phenomena D046368:Crows D005426:Flight, Animal D014921:Wings, Animal
slotted wing tips wind tunnel animal flight flight efficiency jackdaw Corvus monedula separated outer primary feathers