Fjädrarna

Fjädrarna is the term used in Swedish to refer to the feathers of birds and, in some cases, feathered theropod dinosaurs. They form the outer covering of these animals and play essential roles in insulation, buoyancy, flight, and display. Feathers are primarily made of beta-keratin and grow from follicles in the skin. Each feather has a shaft (rachis) with vanes made of barbs and barbules that interlock with tiny hooks, creating a strong and flexible surface.

Birds possess several feather types: down feathers for insulation; contour feathers that define the body shape; flight feathers on the wings (remiges) and tail (rectrices). Additional forms such as semi-plumes and filoplumes contribute texture and sensory function. Feathers grow in cycles, undergoing molts to replace worn or lost feathers; the timing and extent of molt vary by species and season. Preening and the secretion of oil from the uropygial gland help maintain feather condition, waterproofing, and pliability.

Coloration in fjädrarna arises from pigments and structural color. Melanin provides dark tones and enhances wear resistance; carotenoids from diet contribute red and yellow hues; porphyrins add pinkish or red tones in some species. Structural coloration from microscopic architectures can produce iridescence and blues or greens. The arrangement, condition, and color of feathers affect insulation, camouflage, signaling, and aerodynamic performance.

In evolutionary terms, feathers originated in theropod dinosaurs and diversified for flight, thermoregulation, and display. In human culture and economy, fjädrarna have significance in fashion, art, and research. See also: Bird anatomy; Molt; Keratin.