Feathers in Flight
Airplanes, helicopters, jet fighters and even kites are all products of humankind?s fascination with the idea of flight. This is something that birds and their ancestors have been doing since the age of the dinosaurs and that people have been trying to replicate for centuries. Birds can fly for two reasons: they have a light-weight structure and they possess special feathers enabling thrust and lift. There are two kinds of flight feathers; remiges and retrices. Both are pennaceous or vaned feathers and both are always asymmetrical in shape but come in pairs.
Remiges are both primary and secondary feathers located on the wing. The primary feathers are located on the manus. These are used in the flapping motion which provides thrust on the down-stroke to propel the birds. The flexibility of the primary remiges allows the feathers to spread out and avoid wing-tip vortices. These are basically areas around the edges of the feathers where air will swirl around and create drag which inhibits flight.
The secondary flight feathers are located on the ulna. These feathers are not flexible at all and stay close together. This creates a more streamline shape and provides lift in flight. Secondary feathers are shorter than the primary flight feathers but retain the same qualities; asymmetrical but paired.
The retrices are located on the tail and are the steering mechanism of a bird. They act much like a rudder, just as on a boat. When the rudder moves to the right in water, it directs the flow of water so that the boat moves right. They also function as the breaking tool. Most birds have six pairs of retrices but others can have up to twelve pairs.
Most owls have a special adaptation to their flight feathers that allows them stealth flight. They have tiny serrations on the leading edges of their feathers called flutings or fimoriae. These serrations break up the turbulence that normally occurs with other species of birds when the air rushes over the tops of their feathers. Owls that hunt in the daylight do not have this quality.