Which are the characteristic features of feathers and down being used as filing material?

Down and feathers from waterfowl (geese and ducks) are a unique natural resource. They are used as filling material for quilts, pillows and clothing as they offer a combination of qualities such as breathability, humidity transport and thermal insulation together with a low weight. These special features contribute to the homogeneous distribution of feathers and down inside the quilt as well as to the fact that already small amounts of feathers and down are sufficient for the filling of a quilt.
 
Quelle
Verband der Deutschen Daunen- und Federnindustrie e.V.