Description
CDC (Cul de Canard) feathers are feathers near "grease glands" under a duck's tail. Fly tying legend Rene Harrop described CDC in Fly Fisherman Magazine in the following way "CDC (cul de canard) feathers come from the preen gland of ducks. In appearance, they resemble small marabou blood feathers with unconnected fibers that radiate from tapered center stems. Soft yet strong, CDC floats remarkably well; flies tied with CDC are light and delicate on the water, and the fibers seem to pulse with the slightest breeze or motion of current. The ability to float a fly with less material lends a more realistic profile than is possible with conventional materials. Despite its subtlety, even a small amount of CDC is amazingly easy to see on the water."
These finely-fibered duck feathers with unique floating capabilities are often used for tying emergers and dry fly patterns.