Feather

Feathers (Latin pennae, singular penna) are structures of keratin formed by the outer skin of birds (and fossil feathered dinosaurs) that are lifeless in their finished state, and together form the essential outer surface as plumage or feathers. The branch of science that deals with feathers is called plumology.

Feathers, on the one hand, protect the birds from water and cold and, on the other hand, equip them with colors that serve both as camouflage against enemies and as a means of visual communication. In addition, there is the firm contour they give the bird and the support of the ability to fly. Although a single feather is extremely light, a bird's plumage weighs about twice as much as its skeleton.

Etymology

The Old German noun mhd. veder[e], ahd. fedara is based on the Idg. root pet- "to dash off or down on something, to shoot off, to fly".

Types of feathers

There are two basic types of feathers that differ in construction. These are, on the one hand, the contour feathers, which encompass the exterior of the body, and on the other hand, the down feathers (also called down or down), which are located under the cover feathers and act as a heat-insulating layer. The cover feathers protect the down feathers from moisture.

Contour springs

The contour feathers (pennae conturae) are further subdivided functionally into:

• body feathers (pennae conturae generales): the covering feathers of the trunk
• Wing feathers (Remiges): They form the actual wing of the wing at hand (hand-wings) and forearm (arm-wings)
• Rectrices: the feathers of the tail.
• Tectrices: the remaining feathers on the wings and tail.

Undersprings

The down or downs (plumae) form the undercoat. In some birds (e.g. ratites) they are not present.

The nestling down, the feathers of the young birds, are not real down, but modified contour feathers. They also protect against the cold.

Special springs

In addition to these two basic types, there are also various special springs:

• Semi-downs (Semiplumae): They are situated between contour feathers and downs and are located at the transition to the districts without body feathers.
• Filamentous or hair feathers (filoplumae): Their follicles are well innervated, they serve the proprioception of feathering. Filamentous feathers are absent in ostriches and cassowaries.
• Bristle-feathers (Setae): They replace the eye-lashes, with some bird-types, they are trained as Nasalborsten also at the nostrils.
• Powder feathers (pulviplumae): These are present in some birds (e.g. pigeons, waterfowl) and produce a fine, water-repellent dust of keratin granules.

Down


Long-tailed Buzzard Feathers