Down is a fine layer of wispy fibers that lie between the protective outer feathers and the skin of waterfowl like geese and ducks. It grows in large clusters and small clusters. Birds use their down the same way we use it, for insulation. Down keeps the birds warm. It also increases the bird’s buoyancy.
Down fibers differ from feathers in that they don’t have a hard central quill. Instead, each plume of down consists of many tiny fibers that radiate out from a central point with fine filaments radiating from each fiber. Each ounce of down contains around 2 million filaments that intertwine and cross over one another in all directions.
