Many birds have stiff primary or flight feathers, but owl feathers have a special soft leading edge that helps them fly almost silently through the darkness.
When birds fly, air rushes over their wings, creating lift and turbulence. The stiff edge of a normal bird’s wing produces a larger area of turbulence, which makes a whooshing noise. However, the comb-like soft edge of an owl’s wing breaks down the turbulence and muffles the sound of air rushing over the wing surface. The lack of owl-related flight noise helps owls hear prey and keeps prey from hearing their approach.
The plumage of owls is generally cryptic – that is, the colors and patterns of their feathers camouflage them. For example, Snowy Owls live in the tundra and are primarily white, while Great Horned Owls live in the woods and are brown, grey, and white. Changes in cryptic patterns can even be seen within species inhabiting different ranges: Great Horned Owls that live in birch forests tend to be a little lighter than those that live in darker oak or maple forests.
Although cryptic plumage aids camouflage, many owl species have facial and head markings: face masks, ear tufts, and brightly colored irises. Wikipedia states that these markings are more common in species inhabiting open habitats and are thought to be used to signal other owls under low light conditions. Other people have suggested that, like cryptic patterns, tufts and facial markings serve to camouflage owls.
The owl lifts off her branch. Subnivean voles and mice flare briefly in her awareness as they scrabble beneath the snow. Her directional hearing, acute vision, muffled flight, powerful talons, sharp beak, and cryptic plumage make her a formidable predator as she flies silently through the dark woods to her nest.
The Raptor Resource Project