Don't the alulae work as a pivot point for wing "crank", as birds "fold" in their wings to change Lift directly to drag, and facilitate, a hover/perch? I have always watched birds in this way, as they scream toward a fence, and at the last moment, raise AoA to the vertical, and slow precisely above their "landing spot"? The alulae would allow top surface laminar flow, to hide the front spar's glove joint from the airstream, no? The most interesting are Geese, as we have a large Pond, and they are gathering for the next leg of their Southward trek. They do exquisite "straight-ins" seemingly on a rail, with a touchdown and "rollout" that is the envy of any flyperson. They also can perform a hook to final that leaves them motionless six inches above the water, to allow gravity to complete their "alight" on the surface.
bear. We have alot to learn, and admire, in the Aves portion of our World.