Sometimes birds fluff up their feathers which makes them look fat. Birds do this to create air spaces between the feathers. These spaces hold air heated by the body which provides insulation from the cold. After-feathers are small feathers that emerge from the same shaft as a contour feather. Best seen on grouse and ptarmigan, after-feathers help insulate the bird and fill out body contours.
Some people recognize the head feathers as a separate category.
Dena'ina feather technology except the feather clothing described in Bird Clothing. Flight feather shafts of eagles, swans, cranes, cormorants, gulls, and other birds with strong shafts have been used to make snares, fishing equipment, and other items. Although eagles feathers are said to be the strongest, gull feathers appear to have been most commonly employed because they are both strong and easily accessible. Besides their strength, feather shafts are valued for being flexible, light weight, and waterproof. An elder describes them as having the qualities of plastic.