10.6084/m9.figshare.4982672.v1 Marco KleinHeerenbrink Marco KleinHeerenbrink L. Christoffer Johansson L. Christoffer Johansson Anders Hedenström Anders Hedenström Spreading of vorticity and increased span efficiency from Multi-cored vortices support function of slotted wing tips of birds in gliding and flapping flight The Royal Society 2017 animal flight slotted wing tips separated outer primary feathers flight efficiency jackdaw Corvus monedula wind tunnel 2017-05-08 10:41:20 Journal contribution https://rs.figshare.com/articles/journal_contribution/Spreading_of_vorticity_and_increased_span_efficiency_from_Multi-cored_vortices_support_function_of_slotted_wing_tips_of_birds_in_gliding_and_flapping_flight/4982672 Explanation of the relation between spreading of vorticity and induced drag reduction and a short clarification on the high span efficiency observed in quantitative data on gliding flight.