Powder down
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Powder down feathers are located at the back of the cockatiel just above the tail base beneath the outer feathers. These down feathers differ from the usual down as they are exceptionally fine and produce a dust between the frons. The bird takes this dust from its powder down feathers and coats all its external feathers with the dust. This dust mainly provides the bird with some waterpoofing for the main flight feathers so it can still fly in the rain. It also conditions the feathers and keeps the frons of the flight feathers interlocked to provide good lift. Cockatiel down is by far and away the softest down feathers on earth[citation needed]; the powder down feather when beyond use are stripped out by the bird allowing a new one to grow. They differ in appearance in that they are like a fluffy ball and when rubbed between the fingers the powder from the down will cover the fingertips.
Larger species of white cockatoos (such as Sulphur Crested Cockatoo) also have powder down, located on their flanks (sides of the body).