Which mechanism minimizes induced drag during soaring in birds like eagles?

💡 Explanation

When soaring, birds exploit thermals by creating a pressure difference causing air to flow around the wingtips, leading to induced drag, but the slot effect created by spread-out feathers act as individual airfoils. Therefore, spread feathers minimize induced drag, rather than alula deployment vortex generation, or boundary layer suction, which serve other aerodynamic functions.

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