Down - feather soft core and the weak development of the vane. Average feather duvet is a very short rod with a pencil on the top of barbs and has the shape of the brush. Length quill small - less than 1 mm. Length opahalnoy part with the rod can reach 10-20 mm. Beards symmetrically away from the rod, but their number in one millimeter length of the rod is greater than a transition, and are substantially longer. Pushinok beams have barbs whose length is about 1 mm; thickness barbs fluff is about 5-7 microns, they are durable, flexible, elastic. All the plumage of birds are divided into three types: the primaries, contour and down. Adult birds fluff hidden under the contour feathers. Chicks who down cover is not yet developed only covered with down. Pooh holds the contour feathers at some distance from the body, thereby formed between the heat insulating layer stationary or slow-moving air.
