Silent flight in owls

As I was thinking about birds in flight, I thought about owls.  Owls have the advantage that they can fly silently. The primary reason for their silent flight is an adaptation they have in their wings. In most birds, air creates a sound when it rushes over the top part of the wing. The rushing wind creates turbulence, thus creating the sound.  Owls have comb-like feathers along the edge of their primary feathers. These comb-like feathers reduce the turbulence on the wings by breaking it into "micro-turbulences".  This decreases the sound made by turbulence, giving the owls a more silent flight.

Another factor is that owls have big and rounded wings. This enables them to fly buoyantly and without too much effort, meaning that they don't have to flap their wings as much as regular birds.  Not flapping their wings so much also decreases the noise in their flight.