The down of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and

padding Padding is thin cushioned material sometimes added to clothes. Padding may also be referred to as batting when used as a layer in lining quilts or as a packaging or stuffing material. When padding is used in clothes, it is often done in an attempt ...

, used in goods such as

jacket A jacket is a garment for the upper body, usually extending below the hips. A jacket typically has sleeves, and fastens in the front or slightly on the side. A jacket is generally lighter, tighter-fitting, and less insulating than a coat, whic ...

bedding Bedding, also known as bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environm ...

(

duvet A duvet (, ; ), usually called a comforter or (''down-filled'') quilt in US English, and a doona in Australian English, is a type of bedding consisting of a soft flat bag filled with either down, feathers, wool, cotton, silk, or a synthetic a ...

s and

featherbed A tick mattress, bed tick or tick is a large bag made of strong, stiff, tightly-woven material (ticking). This is then filled to make a mattress, with material such as straw, chaff, horsehair, coarse wool or down feathers,Dictionnaire de l'ameub ...

s),

pillow A pillow is a support of the body at rest for comfort, therapy, or decoration. Pillows are used in different variations by many species, including humans. Some types of pillows include throw pillows, body pillows, decorative pillows, and man ...

s and

sleeping bag A sleeping bag is an insulated covering for a person, essentially a lightweight quilt that can be closed with a zipper or similar means to form a tube, which functions as lightweight, portable bedding in situations where a person is sleeping ...

s. The discovery of feathers trapped in ancient amber suggests that some species of dinosaur may have possessed down-like feathers.

Description and etymology

The word ''down'' comes from the

Old Norse Old Norse, Old Nordic, or Old Scandinavian, is a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia and t ...

word ''dúnn'', which had the same meaning as its modern equivalent. The down feather is considered to be the most "straightforward" of all feather types. It has a short or vestigial

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

(shaft), few

barb Barb or the BARBs or ''variation'' may refer to: People * Barb (name), a list of people and fictional characters with the given name or surname * Barb, a term used by fans of Nicki Minaj to refer to themselves * The Barbs, a band Places * Barb, ...

s, and barbules that lack hooks. There are three types of down: natal down, body down and powder down. Natal down is the layer of down feathers that cover most birds at some point in their early development.

Precocial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...

nestlings are already covered with a layer of down when they hatch, while

altricial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...

nestlings develop their down layer within days or weeks of hatching.

Megapode The megapodes, also known as incubator birds or mound-builders, are stocky, medium-large, chicken-like birds with small heads and large feet in the family Megapodiidae. Their name literally means "large foot" and is a reference to the heavy leg ...

hatchlings are the sole exception; they are already covered with contour feathers when they hatch. Body down is a layer of small, fluffy feathers that lie underneath the outer contour feathers on a bird's body.

Powder down

Powder down, or pulviplumes, is a special type of down that occurs in a few groups of apparently unrelated birds. In some species, the tips of the barbules on powder down feathers disintegrate, forming fine particles of

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ...

, which appear as a powder, or "feather dust", among the feathers. These feathers grow continuously and are not moulted. In other species, powder grains come from cells that surround the barbules of growing feathers. These specialized feathers are typically scattered among ordinary down feathers, though in some species, they occur in clusters. All

parrot Parrots, also known as psittacines (), are birds of the roughly 398 species in 92 genera comprising the order Psittaciformes (), found mostly in tropical and subtropical regions. The order is subdivided into three superfamilies: the Psittaco ...

s have powder down, with some species (including the

mealy amazon The mealy amazon has been split into the following species: * Southern mealy amazon, ''Amazona farinosa'' * Northern mealy amazon, ''Amazona guatemalae'' Birds by common name {{Short pages monitor