Kestrel hovering © Ryttersfoto / iStock
Kestrels, known as ‘wind-hoverers’, are often spotted above motorway verges, apparently hanging in the air while seeking out small mammal prey. To maintain this posture, the bird flies into, and at the same speed as, the oncoming wind – the current of air passing over its wings provides the lift it needs.
To maintain the lift, it extends the tips of its wings and fans its tail feathers, and if the wind drops it will flap its wings to increase air movement.
A kestrel’s feathers are better able to withstand the effects of bending (by being stiffer) compared with other falcons, and research has shown that the birds cope with the energy demands of hovering by including tiny pauses, stretching their necks forwards to offset being blown backwards, while keeping their heads in position.
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