Chicken Anatomy: Rooster & Hen Body Parts

Comb type, tail carriage, wing structure, feathered legs and extra toes are conformation traits: they are judged, and inherited, separately from the pigment genes covered everywhere else on this site — each running on its own small set of well-studied genes rather than on the colour loci. But because every colour standard is written in terms of body parts — black "restricted to hackle, tail and wing tips," a wild-type duckwing hen's "salmon breast," mottling on the "wing coverts" — you cannot read those descriptions without knowing the parts. This page is that reference: what each part is, where it sits, how rooster and hen differ, and the main gene or two behind each structural trait. For colour and pattern genetics, see the Genetics Guide.

Head furnishings: comb, wattles, earlobes

The comb is the fleshy, usually red, crest on top of the head. Its shape is itself a standard trait — different breeds are bred to a specific comb type, most of which are the visible result of a small number of well-studied genes:

Comb type	Shape	Seen in
Single	Upright, thin, with 5–6 defined serrations (points) along the top — the default, most familiar shape.	Leghorn, Rhode Island Red, most common breeds
Rose	Broad and flat-topped, covered in small round bumps (papillae), tapering to a single rearward point ("leader" or "spike").	Wyandotte, Dominique, Hamburg, Sebright
Pea	Low, with three small parallel ridges running front to back — the smallest common comb type, and notably frost-hardy.	Brahma, Ameraucana, Buckeye
Cushion	Small, low, smooth-topped and oval, without points or ridges.	Chantecler (bred specifically for cold resistance)
Walnut	Rounded and solid, resembling half a walnut shell.	Silkie, Orloff
Strawberry	Similar to walnut but more oval/pointed at the front.	Malay
V-shaped (horns)	Two small, horn-like points rising from the base of the skull.	Houdan, Crevecoeur, Polish, La Flèche
Buttercup	A single row of points forming a complete circle, like a small crown — unique to one breed.	Sicilian Buttercup

The genes behind it. Comb shape is one of the oldest worked examples in all of genetics — Bateson and Punnett used it in the early 1900s to demonstrate how two genes interact.³ Two independent genes do most of the work, Rose (R) and Pea (P), each dominant over its wild-type absence; their four combinations give the four base combs (a dash means either allele at that slot):

Genotype	Comb
`R/– p/p`	Rose
`r/r P/–`	Pea
`R/– P/–`	Walnut — both dominant genes together
`r/r p/p`	Single — neither dominant allele present

A third gene, Duplex (D, dominant), splits the comb into the twin horns of a V-comb or the open ring of a Buttercup. Two copies of Rose (R/R) also carry reduced fertility in many lines, so rose-combed breeds are often kept heterozygous (R/r). The feathered topknot of a Polish or Silkie is a separate head trait again, raised by the dominant Crest gene (Cr).

Two paired, fleshy appendages hang below the beak: the wattles. Below and slightly behind the eye sits the earlobe, a smaller patch of bare or lightly feathered skin whose colour (red, white, or blue depending on breed) is itself a standard trait, and in most (not all) breeds correlates loosely with egg-shell colour.

RoosterComb, wattles and earlobes are all noticeably larger, thicker and more brightly coloured than a hen's — comb typically stands fully upright.

HenAll three furnishings are smaller and less developed; on single-combed breeds, the hen's comb commonly flops over to one side rather than standing erect.

The wing

A folded wing is built from several distinct feather groups, and how neatly they sit — the wing carriage — is judged in its own right, separately from the wing's colour or pattern.

Primaries — the large outer flight feathers, normally tucked almost entirely out of sight beneath the secondaries when the wing is folded.
Secondaries — the inner flight feathers, visible along the lower edge of the folded wing. This is usually where a breed's wing-bar pattern is judged.
Wing bow — the rounded, feathered upper portion of the wing (closest to the shoulder) when folded.
Wing coverts — the small feathers that overlay the base of the primaries and secondaries. A single row of contrastingly coloured coverts across the wing produces a wing bar; this is also a common site for mottling's white feather tips.

Correct carriage holds the wing snugly folded against the body. Two named faults describe the same wing sitting wrong: a slipped wing, where some primaries hang loose below the secondaries instead of tucking beneath them, and a drooping wing, where the whole wing hangs below the body's lower line. Both are structural faults, unrelated to feather colour.

The genes behind it. Unlike the comb, wing carriage has no single switch gene — how tightly the wing folds and sits is polygenic, the sum of many genes of small effect and of overall body type, which is why it is improved by steady selection rather than by adding one allele. Slipped and drooping wing run in families but are not tied to a named major gene.

RoosterWing structure is otherwise identical between the sexes — carriage and covert names apply equally to both.

HenNo structural difference from the rooster's wing; any colour difference between the sexes at this location comes from the underlying genotype, not the anatomy.

The tail

Main tail feathers — the large, central feathers that give the tail its basic shape.
Sickle feathers (rooster only) — long, curved feathers that arch up and over the main tail. The longer, outer pair are major sickles; the shorter feathers beneath them are minor sickles.
Tail coverts — smaller feathers covering the base of the main tail feathers, adding fullness.

Tail carriage — the angle the tail is held at, relative to the back — is itself a defined standard trait, and the target angle varies enormously by breed: Yokohama and Phoenix are bred for a very low, flowing tail, Modern Game for a near-vertical one, and most breeds sit somewhere in between.

The genes behind it. Two structural genes act on the tail. Rumplessness — no tail feathers and no tail vertebrae at all — comes from the dominant Rp allele (its expression varies, and a separate recessive form also exists), as in the rumpless Araucana. And the rooster's sickles themselves depend on the hen-feathering gene: the dominant Hf allele makes a cock grow rounded, hen-like plumage with no sickles at all (Sebright, Campine), by changing how his skin processes sex hormones rather than by altering the feathers directly.⁴ Tail angle, like wing carriage, is polygenic.

RoosterCarries the long, curved sickle feathers over the main tail — the feature most people picture as a rooster's tail. Generally held higher and more prominently than the hen's.

HenNo sickle feathers — her main tail feathers are shorter, straighter and more uniform in length, and the tail is usually carried at a somewhat lower angle than the rooster's for the same breed.

Neck, back and body feathering: hackle, cape, saddle, cushion

Hackle — the neck feathers, present in both sexes but longer and more pointed in the rooster, where they're sometimes a different, contrasting colour from the body (this is exactly the zone the Columbian and Dark Brown genes are described as clearing black from, or leaving it in).
Cape — the smaller feathers bridging the hackle to the back and shoulders.
Saddle (rooster only) — the long, pointed feathers covering the lower back, just in front of the tail, usually matching the hackle in colour.
Cushion (hen only) — the rounded mass of shorter feathers over the same lower-back area in a hen. It has no rooster equivalent — a cushion is a fuller, more rounded shape than a rooster's saddle, not just a shorter version of it.
Breast — the front of the body below the neck, and often a diagnostic one. The warm "salmon breast" is the mark of a wild-type duckwing (e+) hen, and in a softer form of a wheaten (E^Wh) hen; a brown/partridge (e^b) hen, by contrast, has a stippled or pencilled brown breast free of salmon. That salmon-versus-stippled difference is one of the more reliable ways to tell the e^b and E^Wh bases apart in the hen — see also Partridge & Duckwing.

The genes behind it. Several major genes reshape the plumage of this whole region. Naked Neck (Na, incompletely dominant) bares the neck and thins feathering elsewhere — one copy gives a partly bare neck, two copies the fully bare neck of the Transylvanian Naked Neck. Frizzle (F, incompletely dominant) curls every feather outward, one copy lightly and two copies to a brittle extreme. Silkiness (h, recessive) leaves the feather barbs unhooked so the plumage looks like fur, as in the Silkie.⁴

RoosterHackle and saddle feathers are both long and pointed, and often the same colour as each other even when it differs from the body colour — the classic black-red rooster's gold/orange hackle-and-saddle-over-black-body look comes from exactly this.

HenHackle feathers are shorter and rounder-tipped than the rooster's; there is no saddle, only the rounder cushion described above.

Legs and feet: shank, spur, toes

The shank is the lower leg, between the hock joint and the toes. It is bare (scaled) skin in most breeds, but densely feathered in some (Brahma, Cochin, Silkie). The spur is a hard, pointed, bony projection toward the rear of the shank — a rooster trait, used in dominance displays, though older hens occasionally develop small ones. Most breeds have four toes; a small number of standard breeds (Dorking, Houdan, Silkie, Faverolles, Sultan) are bred with five.

The genes behind it. Feathered shanks (ptilopody) come mainly from two dominant genes, Pti-1 and Pti-2, whose effects add together — the heavily "booted" Brahma or Cochin carries both, a lightly feathered breed only one.⁴ The extra toe of a Dorking, Silkie, Faverolles or Sultan is polydactyly, the dominant Po allele. Both are inherited independently of shank colour and of the bare-versus-feathered distinction itself.

RoosterDevelops a prominent spur on each shank as he matures; legs are generally thicker and set further apart than a hen's.

HenSpurs are normally absent or, in some older hens, small and blunt; legs are proportionally finer.

References & notes

American Poultry Association, American Standard of Perfection — the reference standard defining comb types, feather-region names (hackle, saddle, cushion, wing bow, wing bar, etc.) and carriage/conformation terms used across North American poultry judging.
American Bantam Association, Bantam Standard — parallel conformation and terminology reference for bantam varieties.
Bateson W & Punnett RC (1905–1908), on comb-shape inheritance in the fowl — the Rose × Pea cross that became a classic early demonstration of gene interaction (epistasis).
Somes RG Jr (1990) Mutations and major variants of plumage and skin, and of muscles and skeleton, in the chicken. In: Crawford RD (ed.) Poultry Breeding and Genetics, Elsevier — reference for the major structural genes named here (naked neck, frizzle, silkiness, feathered shanks, polydactyly, rumplessness, hen-feathering).

See these terms in context: Compare Standards · Glossary · Genetics Guide