Anatomy Physiology

Chicken Feathers 101

I’ve posted a series of anatomy and physiology articles about the different systems in a chicken’s body: respiratory; reproductive; digestive; the nervous system and the five senses. I seem to be working my way from the inside out – this piece is about what covers our birds and will look at their anatomy, function, names and types of different feathers.

One of the most common questions on Facebook chicken groups is ‘What breed is this?’ Often folks chime in saying they have a bird that looks just like it so it must be the same breed as theirs. What they are comparing is the appearance of colour or pattern rather than actual conformation of physical attributes. Feathers – the type and pattern – are just one identifying feature of a breed. We both may have black birds, but that in no way means they are the same breed.

Think dogs: we could look at a black Lab and a black Poodle and immediately distinguish the differences between them. Feather colour and pattern are important, but there many other factors that contribute to a breed’s Standard of Perfection (SOP): overall body shape; size or weight; comb type; angle of the tail; number of toes; leg colour, egg colour. The last thing described in the SOP is feathers.

Feathers are made of keratin, which contains amino acids such as cysteine, lysine, proline and methionine. It’s the same material that comprises fingernails, claws, beaks, spurs and hair.

Feathers have a number of functions: flight (ok, not so much for chickens); insulation against heat and cold; waterproofing; protection against the weather and insects; camouflage; courtship; and to assist in their ability to detect air currents and sound vibrations. Their diversity comes from the evolution of small modifications enabling them to serve different functions.

Structure

Each feather has a hard central shaft. The bottom of the mature shaft, a quill, is hollow where it attaches under the skin into the follicle.

Around each follicle are groups of tiny muscles that allow the feather to be raised and lowered, allowing the bird to fluff itself up.

The portion above the skin, where the smaller barbs extend from is called the rachis.

On both sides of the shaft are rows of barbs, and on each barb are rows of barbules. The barbules have tiny hooks along the edge that lock them together like a zipper to make a smooth feather. At the base of the feathers there are often barbs that are not hooked together, called downy barbs.

One of the purposes of preening is to smooth and connect the feather barbs together. Silkies lack barbules, giving them their fluffy appearance.

Developing feathers have a vein in the shaft, which can bleed profusely if the feather is cut or torn. When these pinfeathers start growing they are tightly rolled and look like pins sticking out of the chicken’s skin. They’re covered with a thin, white coating that falls off or is groomed off by preening. When the cover comes off, the feather expands to its full length and the vein dries up.

Just like ingrown hair in people, chickens can have issues with feathers that don’t erupt through the skin. Follicle cysts are oval or elongated nodules, lumps or masses which contain an accumulation of yellow-whitish keratin. They can develop as a result of infection, genetics, previous damage to the feather or any condition that interferes with normal feather growth. Silkies have a genetic predisposition to developing feather follicle cysts due to their unique feathering.

Chickens are constantly losing and replacing new feathers. Once they reach a year old they will go through an annual molt when they will lose and regrow a large number of feathers. During this time hens usually stop laying as the protein they consume is diverted from egg production towards making new feathers.

Types of feathers

There are seven categories of feathers based on their structure and location.

types of feathers bird academy

Contour feathers are the outer feathers that form the bird’s distinctive shape. They include wing, tail and most of the body feathers.

Neck: The row of narrow feathers around the neck, the hackles, can be raised to convey aggression. These feathers are often a different color than the body feathers, and they may be very colorful in roosters. In most males, the hackle feathers are pointed and iridescent, while hens’ have rounded tips and are duller.

Belly and Midsection: The belly and remaining body areas of the chicken are covered with small, fluffy feathers, often lighter in color.

Wings: There are three types: the top section, closest to the body, consists of small, rounded feathers (coverts); middle feathers (secondaries) are longer; primaries are the longest and largest feathers at the end of the wing. Each section overlaps the other just slightly.

Legs: Chicken thighs are covered with soft, small feathers. In most breeds, the feathers end halfway down the leg, at the hock joint. In some breeds, however, the legs have fluffy feathers right down to and covering the toes (e.g. Brahma, Marans).

Tail: Roosters have long, shiny, attractive tail feathers. In many breeds, the top three or four tail feathers are narrower and may arch above the rest of the tail. These are called sickle feathers. Hens have tail feathers, too, but they are short and plainly colored, and they don’t arch.

Feather Patterns

Colour

The colour of feathers comes from a combination of pigments and the way that keratin is arranged in layers within the feathers.

Melanins: brown-black pigments add colour to the feather, make them denser and more resistant to wear and breakdown by sunlight.

Carotenoids: yellow, orange, or red pigments are synthesized in plants, absorbed by the bird’s digestive system, and then are taken up by the cells of the follicle as the feather is developing.

Porphyrins: red and green pigments are produced by cells in the feather follicle.

Iridescent greens and blues usually come from the way light reflects off the layers of keratin. Roosters generally have more iridescent colors than hens. When feathers have lost their shine and appear dull it is often a symptom of a health issue.

Rooster Feathers

An understanding of sexual dimorphism (differences betweens males and females) particularly around feather colour and type can assist you in sexing your birds. I’ve covered that in the post above as well as sexing crested birds. I’ll cover sexing birds, including feather-sexing chicks in future pieces.

Variations

Feathers cover most of the chicken’s body. Transylvanian Naked Necks carry a gene so they have no neck feathers. Crosses that carry one copy of the gene will have partially naked necks, referred to as a ‘bowtie’.

Most breeds have clean legs, but some have feathers growing down their legs and even on their toes (e.g. Marans, Faverolle, Brahma).

I have birds that carry genes for other feather variations: muffs (fluffy feathers on their cheeks); beards (hanging feathers below their beak); and crests (longer feathers on their head that might fall over their eyes, be more upright like Mohawks or small poufs). Araucanas have tufts, tiny clumps of feathers that grow outwards beside their ears.

Breeds that appear more rounded are called soft-feathered (e.g. Cochin) while those that look smooth and sleek are called hard-feathered.

I have four frizzled hens, who carry a gene that causes their feather shafts to curl making them look fluffy, like a feather duster. Frizzles are not a breed, but a genetic mutation that can occur in various breeds.

Here is a glossary of terms to help you understand the language of feathers better.

Glossary

  • Axial feather: short wing feather located between the primary and secondary flight feathers
  • Barb: individual strand of feather material extending laterally from the rachis
  • Barbicel: tiny hook that hold feathers together
  • Barbule: a lateral branch of a feather barb
  • Barring: alternate markings of two distinct colors on a feather (Plymouth Barred Rock)
  • Beard: hanging feathers under the lower beak/on neck of some breeds (Ameraucana)
  • Booted: feathers on the shanks and toes
  • Bristle: hair-like structure located around the eye and head; plays a sensory role
  • Cape: narrow feathers between the neck and back
  • Clean legged: no feathers on the legs
  • Clubbed down: condition where the down feathers do not erupt from their feather sheath resulting in a coil-like appearance
  • Covert: the top section, of the wing closest to the body; consists of small, rounded feathers
  • Crest: puff of feathers on the head (Appenzeller Spitzhauben, Silkie, Polish)
  • Down: soft fluff covering a newly hatched chick; fluffy part near the base of any feather
  • Feather legged: feathers growing down the shanks (Cochin, Brahma)
  • Filoplume: tiny, wisp-like feathers that grow around the base of contour and semiplume feathers; attached to nerve endings that provide information about the environment and condition of their feathers
  • Flight feather: large primary and secondary feather of the wings
  • Fluff: down feathers
  • Frizzle: gene that creates curled, rather than smooth, feathers
  • Hackle: feathers on the neck, which are more pointed in males and rounded in females
  • Hen feathered: a rooster having rounded rather than pointed sex feathers
  • Laced: cup shaped line along the outer edge of the feather
  • Molt: annual shedding and regrowing feathers
  • Mottled: loss of pigment in the tip of each feather, so the tip is grey or white. After the white tip there’s a black strip and then whatever the bird’s normal plumage color would be
  • Muff: feathers sticking out from both sides of the face; always found in association with a beard (Ameraucana, Faverolle, Houdan)
  • Penciled: lines or bars on feathers that form a pattern
  • Pinfeathers: tips of newly emerging feathers
  • Plumage: total set of feathers covering a bird
  • Preen: straighten and clean feathers, typically with oil
  • Primary: longest and largest feathers at the end of the wing
  • Quill: bottom of a mature feather shaft below the skin
  • Rachis: portion of a feather shaft above the skin
  • Saddle: feathers at the base of a chicken’s back just before the tail
  • Secondary: middle wing feathers (between covert and primaries)
  • Semiplume: a cross between a contour and down feather that add extra insulation in addition to the down feathers.
  • Sex feather: hackle, saddle or tail feather that is usually rounded in a hen and  pointed in a rooster
  • Shaft: hard, central structure in a feather
  • Shafting: feather shaft is one color and the vane (body) of the feather is another
  • Sickles: long, curved tail feathers of some roosters
  • Smut: black feathers that are uncharacteristic for the breed (black body feathers in a Rhode Island Red)
  • Spangled: lack of pigment in the center of the feather, giving the appearance of spots (Appenzeller Spitzhauben, Hamburg)
  • Stub: down on the shank or toe of a clean-legged chicken
  • Tufts: feathers that protrude outward from the face near the ears (Araucana)
  • Vulture hock: feather-legged breeds where the feathers grow down from the shank and touch the ground
  • Wing clipping: cutting of the primary wing feathers of one wing to prevent flight

Artwork in Featured Photo at top courtesy of Jan Ellison.

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