Birds' "thumbs"

Usage examples of alulae.

I climbed to the roof with powerful beats, increasing my angle of attack and slotting my alulae for lift without burble -- climbing at an angle that would stall most fliers.

I completed my stoop in front of the gallery, lowering and spreading my tail so hard I could feel leg muscles knot and grabbing air with both wings, alulae slotted.

We went back to the tourist slope and I let her glide, cautioning her to hold both alulae open with her thumbs for more lift at slow speeds, while barely sculling with her fingers.