Plymouth Rock Chicken

Gallus gallus domesticus

The domestic chicken (Gallus gallus domesticus) is the world's most common bird, with more than 26 billion alive at any one time. It was tamed from the red junglefowl of South and Southeast Asia. Hens and roosters both have a fleshy red comb on the head and wattles under the beak, but a rooster's are bigger, and only roosters grow long, curved sickle feathers in the tail. People now keep many breeds, from white Leghorns that lay almost an egg a day to fluffy Silkies.

Also known as Chicken, Domestic fowl, Hen

Domestic chicken abilities

24–26 h to build one egg
Inside a laying hen, a yolk travels down a long tube called the oviduct. Along the way it gets its white, two thin skins and a hard shell. The whole trip takes about a day.
- Only the left ovary works. The right one stops developing when the hen hatches. The left ovary holds several thousand tiny yolks-to-be.
- The yolk spends about 15 minutes in the funnel at the top, 3 hours getting most of its white, and a little over an hour getting its shell membranes.
- The longest stop is the shell gland, about 20 hours, where the shell is built and coloured.
- About 30 minutes after an egg is laid, the next yolk is released. A hen does not need a rooster to lay: without one, her eggs are simply not fertilised.
Sources [3, 4]
21 days from egg to chick
A broody hen sits on her eggs to keep them warm. After 21 days the chicks break out of their shells.
- The chick's heart starts beating after about 42 hours.
- On day 20 the chick pokes its beak into the air pocket at the blunt end of the egg and starts breathing with its lungs.
- On day 21 it cuts through the shell with its egg tooth, a hard tip on its beak, and hatches. A new chick weighs about 37 g.
- Some breeds go broody much more often than others. Silkie hens are so broody that people use them to hatch other birds' eggs.
Sources [1, 18, 24]
Age 6 when its discoverer began watching hens
Hens in a flock sort themselves into a ranking. A higher-ranking hen can peck a lower one, and the lower hen backs down instead of pecking back. Knowing their places means fewer fights.
- The Norwegian scientist Thorleif Schjelderup-Ebbe was already watching chickens and writing down what they did by the age of six. His first study was based on summer holidays at his grandmother's farm.
- He found that hens recognise each other and remember their rank. The order did not simply follow size or age, and sometimes three hens formed a triangle: A beats B, B beats C, but C beats A.
- A dominant bird holds its head and tail up. A lower-ranking bird lowers them and crouches.
- In very large farm flocks the order is harder to keep, and there is more pecking.
Sources [5, 6, 29]
34.6 °C average in a 50-hour heat test
On a hot day, warm blood flows into the bare comb and wattles, and heat escapes through the skin. It works a little like a car's radiator.
- In a 2016 study, some White Leghorn pullets had part of their comb and wattles trimmed. Later, all the hens spent about 50 hours in heat averaging 34.6 °C.
- The trimmed hens got hotter and more of them died, while the hens with whole combs and wattles coped better.
- In mild weather the trimmed hens were fine, so the comb matters most when it is hot.
- The comb is also a signal: in tests with red junglefowl, hens that chose quickly picked roosters with longer combs.
Sources [11, 12]
142 dB at the rooster's own ear
Roosters crow to announce themselves. They crow before dawn even without a light to tell them the time, because an internal body clock wakes them up.
- In a 2013 study, 40 roosters kept in constant light still crowed at the time daybreak would have come.
- In groups of four, the top-ranking rooster crowed first on almost every morning (97.6%). The others followed in order of rank.
- A crow measured at the entrance of the rooster's ear reached 142.3 dB. Half a metre away it was about 102 dB.
- When a rooster opens his beak to crow, his ear canal closes, so he does not deafen himself.
Sources [7, 8, 9]
2 kinds of alarm call
Roosters have one alarm call for danger in the sky and a different one for danger on the ground. Hens that hear the call know what kind of danger it is and act the right way.
- In a 1993 experiment, a video of a hawk soaring overhead made roosters give the aerial alarm. A video of a raccoon made them give the ground alarm.
- When scientists played the calls back with no predator in sight, hens crouched and ran for cover after the aerial call.
- After the ground call they stood tall and watched instead.
- Only the aerial call made hens look up at the sky.
Sources [1, 10]
0 teeth: the gizzard does the chewing
With no teeth, a chicken swallows grain whole. It is stored in the crop, softened in an acid stomach and then crushed in the gizzard, a tough muscular stomach.
- The crop is a pouch in the neck that stores food and water. When it is nearly empty, the chicken feels hungry.
- The gizzard has two sets of strong muscles that work like teeth.
- Chickens out on grass swallow small stones, called grit, which help the gizzard grind.
- Chickens fed whole grains without enough pebbles need grit added to their food.
Sources [14]
Stale oil what a dust bath scrubs off
Chickens clean their feathers with dirt. A hen scrapes a hollow, wriggles into loose earth, flicks it through her feathers and then shakes it all out.
- When a chicken preens, it spreads oil from a gland near its tail over its feathers to keep them supple. Over time the oil gets old and stale.
- A dust bath soaks up the extra oil and helps get rid of skin parasites.
- Free-range hens spend a lot of time dust bathing and dig hollows in their favourite spots.
- Hens with nothing loose to bathe in may 'pretend' bathe on a bare floor, and may start pecking each other's feathers.
Sources [15]

Real chickens

Photos from Wikimedia Commons. Some of them can repaint the 3D model.

Crowing at sunrise: tall comb, long wattlesPhoto: Muhammad Mahdi Karim, GFDL 1.2
A rooster crows in the snow; note the curved sickle feathersPhoto: GrinningIodize, CC BY-SA 4.0
Brown laying henGinger-brown feathers, a small single comb, small wattles and red earlobes.A typical backyard and farm egg layerA brown hen in her dust-bath hollow. Photo: Dave Crosby, CC BY-SA 2.0
Hen with chicksFluffy chicks covered in down stay close to their mother.Chicks hatch after 21 days, covered in fluffy downA free-range hen and her chicks. Photo: Nathaly 1106, CC BY 4.0
White (Leghorn), speckled (Marans) and tinted (Rhode Island Red) eggsPhoto: Timothy Titus, CC BY-SA 3.0
White LeghornAll white, with a single comb, white earlobes and bright yellow legs.Lays about 280 white eggs a year. The world record layer was a White LeghornA White Leghorn hen: pale earlobe, yellow legs. Photo: Stephen Ausmus, USDA ARS, Public domain
Rhode Island RedDeep red to almost black-red feathers with a mostly black tail, red earlobes and yellow legs.Lays brown eggs. It is the state bird of Rhode IslandA Rhode Island Red rooster. Photo: Dictouray, CC BY-SA 3.0
Barred Plymouth RockGrey-and-white barred feathers, a single comb, red earlobes and yellow legs.Raised for both eggs and meat; about 200 brown eggs a yearA Barred Plymouth Rock hen. Photo: Jena Fuller, CC BY-SA 2.0
SilkieFluffy, fur-like feathers that cannot hold together for flight, a pompom crest, a dark walnut comb, turquoise earlobes, black skin and five toes on each foot.Kept as pets and as broody hens that hatch other birds' eggsA white Silkie: fluffy crest, turquoise earlobe. Photo: Benjamint444, CC BY-SA 3.0
The wild ancestor: a red junglefowl rooster, Chitwan, NepalPhoto: Lip Kee from Singapore, Republic of Singapore, CC BY-SA 2.0

Chickens by the numbers

Measured by poultry scientists, record keepers and researchers.

Eggs a year: 200–300+; commercial-type hens 200–260; some breeds over 300; many purebreds 100–180⁠[19, 1]
Egg-laying record: 371 in 364 days; a White Leghorn, No. 2988, in an official test ending in 1979 at the University of Missouri⁠[20]
Time to make an egg: 24–26 hours; about 20 of those hours in the shell gland⁠[3, 4]
Egg to chick: 21 days; a new chick weighs about 37 g⁠[18, 1]
First eggs: ≈20 weeks old; for laying hens⁠[19]
Weight: 2–4 kg; Leghorn hens 2.0–2.5 kg; Rhode Island Red roosters about 3.9 kg⁠[21, 22]
Loudest crow measured: 142.3 dB; at the rooster's own ear; about 102 dB half a metre away⁠[9]
Kinds of cone cell in the eye: 5; including one that sees some ultraviolet⁠[13, 30]; Chicken5 You3
Lifespan: 5–10 years; depending on breed; the oldest on record, Muffy, lived 23 years⁠[1, 31]
Chickens alive: 26.5 billion+; in 2023: more than any other bird⁠[1]

Chicken myths and facts

Tap Myth or Fact for each claim, then check the answer.

0 of 7 answered

“A hen needs a rooster to lay eggs.”
“Brown eggs are healthier than white eggs.”
“A hen with red earlobes usually lays brown eggs.”
“Roosters only crow at dawn.”
“Chickens can't fly.”
“Chickens see more colours than people do.”
“The biggest hen is always top of the pecking order.”

What to call a chicken

Chickens have different names depending on their age and sex.

Rooster or cock
An adult male chicken.⁠[1]
Hen
An adult female chicken.⁠[1]
Cockerel
A young male chicken.⁠[1]
Pullet
A young female chicken, less than a year old.⁠[1]
Chick
A baby chicken, newly hatched and covered in down.⁠[1]
Chook or biddy
Other everyday names for a chicken.⁠[1]

A chicken's life

From a yolk inside a hen to a hen laying eggs of her own.

Day 0
An egg is laid
After 24–26 hours travelling through the hen, the egg is laid. If it was fertilised and a hen sits on it, a chick starts to grow.⁠[3]
About 42 hours
First heartbeat
The tiny embryo's heart starts beating.⁠[18]
Day 14–17
Getting into position
The chick moves into position for hatching, and by day 17 its beak points towards the air pocket at the blunt end.⁠[18]
Day 20
First breath
The beak breaks into the air pocket and the chick starts breathing with its lungs, still inside the shell.⁠[18]
Day 21
Hatching
Using its egg tooth and strong neck muscles, the chick cuts its way out. It weighs about 37 g.⁠[18, 1]
First year
Pullets and cockerels
Young females are called pullets and young males cockerels. Hackle feathers start to show the difference: pointed in males, rounded in females.⁠[1, 16]
About 20 weeks
First eggs
Laying hens start to lay at around 20 weeks old.⁠[19]
5–10 years
Old age
Most chickens live 5 to 10 years, depending on the breed. The oldest on record, a hen called Muffy, lived to 23.⁠[1, 31]

Domestic chicken vs red junglefowl vs common pheasant

The chicken's wild ancestor, and a wild cousin that people often mix up with it.

Domestic chicken vs red junglefowl vs common pheasant
	Domestic chicken	Red junglefowl	Common pheasant
Scientific name⁠[1, 25, 28]	Gallus gallus domesticus	Gallus gallus	Phasianus colchicus
Wild or tame⁠[1, 25, 28]	Domestic, kept by people all over the world	Wild; the main ancestor of the chicken	Wild
Weight⁠[21, 22, 25, 28]	About 2–4 kg in common breeds	Males about 1.5 kg, females about 1 kg	Males about 1.2 kg, females about 0.9 kg
Head⁠[1, 25, 28]	Red comb and wattles in both sexes, bigger in roosters	Red comb and wattles, bigger in males	Males: green head, red face wattle and ear tufts
Flying⁠[1, 25, 28]	Short distances only	Flies up to roost in trees at sunset	Short, fast bursts; prefers to run
Native to⁠[2, 25, 28]	Tamed in Southeast Asia; now worldwide	South and Southeast Asia	Asia, from the Caucasus to Korea and Taiwan
IUCN status⁠[25, 28]	Not assessed (domestic)	Least Concern	Least Concern

Chickens come mainly from the red junglefowl, but they also carry some genes from other junglefowl, including the gene for yellow skin from the grey junglefowl.

Is the chicken endangered?

Chickens are the most numerous bird on Earth, but many old breeds are rare, and the wild ancestor faces a quiet problem.

IUCN Red List

Not Evaluated (NE)

The domestic chicken is not on the IUCN Red List. Its wild ancestor, the red junglefowl, is listed as Least Concern.⁠[25, 1]

Domestic animals are not assessed by the IUCN

Threats

Old breeds dying out12
Chicken breeds rated Critical on the US Livestock Conservancy's 2026 Conservation Priority List, including the Araucana and the Java.⁠[27]
Mixing with the wild ancestor
Where free-ranging village chickens meet forest edges, they breed with wild red junglefowl, which may water down the junglefowl's wild traits.⁠[25]

What’s helping

Breed watch lists
The Livestock Conservancy tracks rare chicken breeds in four groups, from Critical to Recovering, so breeders know which ones need help.⁠[27]
Breeds that bounced back
Non-industrial Leghorns, Delawares, Jersey Giants, Polish and Sussex chickens are now listed as Recovering.⁠[27]

Its wild ancestor

Red junglefowlLeast Concern
The wild ancestor, still common in the forests of South and Southeast Asia.⁠[25]

Chicken quiz

12 questions. Every answer is somewhere on this page.

Question 1 of 12Score 0

About how long does a hen take to make one egg?

Plymouth Rock Chicken field notes

Diet, food web, safety and badges from the Snappit field guide.

Diet & Feeding

An omnivore, it pecks and scratches for seeds, grains, insects, and leafy greens.

Primary Foods

seeds
grains
insects
worms
grasses
leafy greens
Foraging Method: Foraging

Ecological connections

coyoteEaten by
Opportunistic predator in rural areas.
red foxEaten by
A common predator of poultry in many regions.
red-tailed hawkEaten by
Preys on smaller ground animals including chickens.

Safety

Danger 1/5 · Very low

Always be gentle and calm around chickens. They are friendly but can be startled easily.

Traits

Collections

Birds

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Genus: Gallus

Also known as

Chicken · Domestic fowl · Hen · Rooster · Chook · Barred Rock

Sources for these chicken facts

31 studies and references · checked Oct 28, 2026

Frequently Asked Questions

How to identify Plymouth Rock Chicken?

Compare the silhouette, bill shape, tail length, wing bars and markings around the eyes. The same small brown bird at your feeder can look quite different in breeding plumage, winter plumage or its first year. Bird Identifier: upload a photo and compare the visible details.

How long is Plymouth Rock Chicken?

45-55 cm

What is Plymouth Rock Chicken's wingspan?

60-70 cm

How much does Plymouth Rock Chicken weigh?

2.9-4.3 kg

How long does Plymouth Rock Chicken live?

6-10 years

How fast can Plymouth Rock Chicken move?

15 km/h

What does Plymouth Rock Chicken eat?

An omnivore, it pecks and scratches for seeds, grains, insects, and leafy greens.

How does Plymouth Rock Chicken hunt?

Foraging

Do hens need a rooster to lay eggs?

No. A hen lays eggs whether or not there is a rooster. Without one, the eggs are not fertilised and cannot hatch.

How long does it take a hen to make an egg?

About 24 to 26 hours. Most of that time, about 20 hours, is spent in the shell gland, where the hard shell is made.

Why do chickens have a comb?

The bare comb and wattles help chickens lose heat on hot days. The comb is also a signal: in tests, junglefowl hens that chose quickly picked roosters with longer combs.

Why do roosters crow in the morning?

An internal body clock makes them crow before dawn, even in constant light. In a group, the top-ranking rooster usually crows first.

What is a pecking order?

It is the ranking inside a flock. Higher-ranking hens can peck lower ones without being pecked back. It was first described by Thorleif Schjelderup-Ebbe, who studied hens from childhood.

Why do chickens roll in dirt?

That is a dust bath. It soaks up stale oil from the feathers and helps get rid of skin parasites.

When and where were chickens domesticated?

The oldest bones that are clearly from chickens come from central Thailand, about 3,500 years ago, probably after red junglefowl were drawn to rice and millet fields. Some genetic studies suggest an earlier start, so the exact date is still debated.

How long do chickens live?

Usually 5 to 10 years, depending on the breed. The oldest on record, a hen called Muffy, lived to 23.

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