These featherswhich are attached to the bird's 'thumb' and normally lie flush against the anterior edge of the wingfunction in the same way as the slats on an airplane wing, allowing the wing to achieve a higher than normal angle of attack and thus lift without. Since these species are not closely related to modern birds, either the alula evolved twice, or it did so more than 130 million years ago. However, alula feathers are definitely an aid to slow flight. The presence of an alula has been confirmed in several now- extinct ancient relatives of modern birds, including Eoalulavis hoyasi (an enantiornithine from the mid- Cretaceous, 115 mya) and the earlier Protopteryx fengningensis. The Alulae are particularly notable in peregrine falcons. In falcons, the alula is more prominent, and provides a degree of control when the wing is cupped or tucked in a dive/stoop. During stretching of the wing down toward the ground, the alula is abducted from the wing and can be clearly viewed. The tip of the alula forms a tiny vortex that forces the airflow over the wing to better bind to it. primary feather to the leading-edge location where the lesser coverts and alula feathers intersect. Feminas is a kind of wing plume similar but from the female bird. The wing feathers have thicker stems than drabs. The enormous wing plumes of male birds can vary between 20 to 30 inches long with a width that can measure 12 inches across. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall. The distance of the alulas root to the wing tip, d. Ostrich wing feathers are also referred to as ostrich plumes. When flying at slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing's leading edge. The feathers attached to that thumb are called. In most situations, the alula is held flush against the wing however, it can be manipulated. The alula of a bird is a small free-moving structure between the hand and arm wing, sometimes called a thumb. Adult bald eagle landing, showing the alula in action
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