---
title: "What the sources say about the Chicken | AnimalTracks.wiki"
description: "53 claims from the Chicken profile, each beside the words of the source that backs it."
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canonical: "https://animaltracks.wiki/animals/chicken/sources/"
---

# What the sources say about the Chicken (*Gallus gallus domesticus*)

> 53 claims from the Chicken profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Chicken](https://animaltracks.wiki/animals/chicken/)

## Ohio 4-H Poultry Resource. Ohio State University Extension.

https://muskingum.osu.edu/sites/muskingum/files/imce/Program_Pages/4H/Member_Resources/Livestock_Resources/Ohio%204-H%20Poultry%20Resource.pdf

| The page says | The source says |
| :--- | :--- |
| whose gizzard does the chewing | the gizzard is made up of two sets of strong muscles that act as the bird's teeth (note: tagline) |
| whose hen usually lays an egg every 26 hours | A hen usually lays one egg every 26 hours (note: tagline) |
| Farms and backyard flocks | After you have decided the goal for your backyard flock (eggs, meat or show) (note: stats.habitat: backyard flocks) |
| Poultry feed with grains such as corn, wheat and barley | Important sources of carbohydrates in poultry diets include corn, wheat, barley, and other grains. (note: stats.diet; the passage says poultry, and the whole document is about chickens) |
| free-ranging chickens typically eat small stones | When allowed to free-range, chickens typically eat small stones. (note: stats.diet) |
| A muscular gizzard that acts as its teeth and grinds the small stones free-ranging chickens typically eat | the gizzard is made up of two sets of strong muscles that act as the bird's teeth ... When allowed to free-range, chickens typically eat small stones. ... the strong muscles of the gizzard grind them into tiny pieces (note: stats.superpower) |
| has no teeth | because birds do not have teeth (note: body) |
| Its gizzard, a stomach chamber made of two sets of strong muscles, acts as the bird's teeth. | the gizzard is made up of two sets of strong muscles that act as the bird's teeth |
| Free-ranging chickens typically eat small stones, and the gizzard grinds them into tiny pieces. | When allowed to free-range, chickens typically eat small stones. The acidic environment in the proventriculus softens the stones, and then the strong muscles of the gizzard grind them into tiny pieces. |
| Grains such as corn, wheat and barley are important sources of the carbohydrates in poultry diets. | Important sources of carbohydrates in poultry diets include corn, wheat, barley, and other grains. |
| Raised with good care, the fastest-growing meat birds, the Cornish Cross (a Cornish chicken crossed with a White Rock), weigh 4 to 6 pounds at about seven weeks and 6 to 10 pounds at eight to 12 weeks. | The fastest growing birds are a Cornish chicken crossed with a White Rock, which is referred to as a Cornish Cross. Using good livestock care practices, producers will have fryers at approximately seven weeks weighing 4 to 6 pounds, reaching roasting stage of 6 to 10 pounds in eight to 12 weeks. (note: scope: Cornish Cross meat birds at those ages only, not chickens generally; 'raised with good care' carries 'Using good livestock care practices'; 'meat birds' from the Meat Production section heading) |
| The average lifespan of a chicken is seven to eight years. | potentially seven to eight years, which is the average lifespan of a chicken |
| A hen usually lays one egg every 26 hours. | A hen usually lays one egg every 26 hours |
| Ovulation, the ovary's release of an egg cell, almost never happens after 3:00 p.m. | the ovary releases the next ovum. However, the female chicken reproductive system is sensitive to light exposure, especially the number of hours of light in a day. In chicken hens, ovulation usually occurs under normal daylight conditions and almost never after 3:00 p.m. |
| A hen that lays too late in the day skips a day. | when a hen lays an egg too late in the day, the next ovulation occurs the following day, and the hen has a day when it does not lay an egg |
| Chicks typically show no competitive behavior until after three days of age, and fighting to set the pecking order, the flock's social ladder, begins by 16 days. | Recently hatched chicks do not typically show any competitive behavior until after three days of age. By 16 days of age, fighting to determine the pecking order begins. (note: 'the flock's social ladder' glosses the source's 'a social hierarchy within chicken flocks') |
| Hens lay eggs without a rooster, but those eggs are not fertile. A rooster is needed only if you want fertile eggs to hatch into chicks. | A rooster is not needed for egg production. Hens will lay nonfertile eggs without a rooster, a rooster is only needed if you want fertile eggs in order to hatch chicks. |
| A hen has sperm host glands that can store sperm, typically for 10 days to 2 weeks. | deep glands known as sperm host glands that can store sperm for long periods of time, typically 10 days to 2 weeks |
| Hearing seems to be an important one. When another hen was put in the mother's place in the dark, the chicks still found their mother. | hearing seems to be an important one. When a sitting hen was removed in the dark from her chicks and another broody hen put in her place, the chicks still found their mother hen. |
| chicks from three breeds of hens, placed in a pen with hens of those breeds, mostly found the correct breed. | When chicks from three different breeds of hens were removed and placed in a pen with hens of the same breed, most of the chicks were able to find to the correct breed of the mother hen. |
| After three weeks of age, chicks were less effective at picking out their own hen in a mixed group. | When chicks from different hens were combined and allowed to mingle, they were able to locate the appropriate hen when the hens were placed with the group. After three weeks of age, the chicks were less effective in doing so. |
| The 26-hour egg clock | A hen usually lays one egg every 26 hours (note: blockquote lead-in; the sentence beneath keeps 'usually') |
| Farms and backyard flocks | There are a variety of cleaning and disinfecting materials available for use on organic poultry farms (note: stats.habitat: farms) |
| Chickens now live in backyard flocks and on farms | After you have decided the goal for your backyard flock (eggs, meat or show) |
| Chickens now live in backyard flocks and on farms | There are a variety of cleaning and disinfecting materials available for use on organic poultry farms |
| A hen usually lays one egg every 26 hours | A hen usually lays one egg every 26 hours (note: vibe.reason; same quote as the body claim) |
| a hen that lays too late in the day skips a day | when a hen lays an egg too late in the day, the next ovulation occurs the following day, and the hen has a day when it does not lay an egg (note: vibe.reason; same quote as the body claim) |
| tags: omnivore | In addition, when given a worm, even if alone, these chicks ran around as though there might be others in pursuit of the worm. Research has shown that chicks instinctively show fear of stinging insects but try to catch flies. (note: #981: kept. Chicken-specific (a chick behaviour study), animal food on top of the grain diet the profile states) |
| tags: omnivore | Although most poultry will eat insects when allowed open access, geese will graze the grass. (note: #981: poultry scope, which includes chickens; second support) |
| tags: domestic-pet | If you are planning to have a small backyard flock of only three to five birds that are enjoyed as pets as well as producers in the local food chain for the family, you may consider a more docile breed. (note: #981: kept as pets too) |

## Chicken. Smithsonian's National Zoo and Conservation Biology Institute.

https://nationalzoo.si.edu/animals/chicken

| The page says | The source says |
| :--- | :--- |
| outnumbers every other bird species | There are more chickens on Earth than any other bird species. (note: tagline; 'every other' paraphrases 'any other') |
| a domestic subspecies of the red junglefowl, a species native to southern Asia | Domestic chickens are a subspecies of red junglefowl (Gallus gallus) , a species native to southern Asia. |
| Not Evaluated | they are domesticated animals and are not threatened or in danger of being threatened (note: stats.conservationStatus. The Smithsonian page says only that Kids' Farm animals are domesticated and not threatened; it does not say Not Evaluated. GBIF's Red List category for Gallus gallus domesticus (accepted usage keys 217145895 and 323329087) returns nothing, checked 2026-09-29, so the domestic form has no Red List category; the red junglefowl assessment (LC 2024) is the wild ancestor's and is not cited. Precedent domestic-cat, domestic-dog.) |
| Chickens have four claws on each foot, used to scratch into the earth to find food. | Chickens have four claws on each foot, which are used to scratch into the earth to find food. |
| Exact size varies greatly among breeds. | Exact size varies greatly among breeds |
| Chickens are diurnal, meaning active by day, and social. | Chickens are diurnal, social animals (note: 'meaning active by day' is the writer's gloss of diurnal) |
| A flock is one rooster with several hens. | with one rooster and several hens making up a flock |
| A rooster's crow is a shrill call used to communicate territory to other males. | Roosters are known for their characteristic crow. This shrill call is used to assertively communicate territory to other males. |
| Hens will not crow, but may cluck to talk to chicks or after laying an egg. | Hens will not crow, but may cluck to communicate with chicks or after laying an egg. |
| Domestic chickens are a subspecies of the red junglefowl, a species native to southern Asia. | Domestic chickens are a subspecies of red junglefowl (Gallus gallus) , a species native to southern Asia. |
| There are more chickens on Earth than any other bird species. | There are more chickens on Earth than any other bird species. |

## Rubin et al. (2010). Whole-genome resequencing reveals loci under selection during chicken domestication. Nature.

https://doi.org/10.1038/nature08832

| The page says | The source says |
| :--- | :--- |
| One of the most striking selective sweeps, where a favourable gene variant spreads through a population, was found in all domestic chickens. | identify selective sweeps of favourable alleles ... One of the most striking selective sweeps found in all domestic chickens occurred at the locus for thyroid stimulating hormone receptor (TSHR) (note: 'where a favourable gene variant spreads' glosses 'selective sweeps of favourable alleles') |
| It sits at the locus for the thyroid stimulating hormone receptor, which is involved in metabolic regulation and photoperiod (day-length) control of reproduction. | the locus for thyroid stimulating hormone receptor (TSHR), which has a pivotal role in metabolic regulation and photoperiod control of reproduction in vertebrates (note: 'day-length' glosses photoperiod) |
| tags: domestic-pet | During the twentieth century, specialized layer and broiler breeds were established to circumvent the inherent conflict in selecting for both growth traits (meat production) and reproductive traits (egg production) (note: #981: the tag's definition is 'selectively bred alongside humans') |

## Eriksson et al. (2008). Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken. PLoS Genetics.

https://doi.org/10.1371/journal.pgen.1000010

| The page says | The source says |
| :--- | :--- |
| The red junglefowl was presumed to be the sole wild ancestor, but a 2008 study traced the yellow-skin gene to a different species, most likely the grey junglefowl. | yellow skin does not originate from the red junglefowl ( Gallus gallus ), the presumed sole wild ancestor of the domestic chicken, but most likely from the closely related grey junglefowl ( Gallus sonneratii ) (note: 2008 is the reference's publication year) |
| Its authors called this the first conclusive evidence that the domestic chicken has a hybrid origin. | This is the first conclusive evidence for a hybrid origin of the domestic chicken |

## Shimmura, Ohashi & Yoshimura (2015). The highest-ranking rooster has priority to announce the break of dawn. Scientific Reports.

https://doi.org/10.1038/srep11683

| The page says | The source says |
| :--- | :--- |
| In a 2015 study of small groups, the top-ranking rooster almost always started to crow first each morning, followed by lower-ranking roosters in descending order of rank. | The top-ranking rooster almost always started to crow first every morning (97.6 ± 2.9%; Fig. 1c ), followed by lower-ranking roosters in descending order of social rank (note: 2015 is the reference's publication year) |
| The ladder even decides who crows first. | when chickens were housed in small groups, the top-ranking rooster determined the timing of predawn crowing |

## Storey et al. (2012). Investigating the Global Dispersal of Chickens in Prehistory Using Ancient Mitochondrial DNA Signatures. PLoS ONE.

https://doi.org/10.1371/journal.pone.0039171

| The page says | The source says |
| :--- | :--- |
| Ancient DNA from directly dated chicken bones, about 1000 years old in Europe and about 3000 years old in the Pacific, indicates multiple prehistoric dispersals from a single Asian centre. | Haplogroup E mtDNA signatures have been amplified from directly dated samples originating in Europe at 1000 B.P. and in the Pacific at 3000 B.P. indicating multiple prehistoric dispersals from a single Asian centre. |
| A Polynesian origin for pre-Columbian chickens found in Chile has been proposed, and questioned by some. | A Polynesian origin for pre-Columbian chickens recovered from the archaeological site of El Arenal in Chile has recently been proposed ... While this has been questioned by some |
| People spread the birds themselves. | support for archaeological hypotheses about the prehistoric human transport of chickens (note: linking sentence to the dispersal claim below it) |

## Lawal et al. (2020). The wild species genome ancestry of domestic chickens. BMC Biology.

https://doi.org/10.1186/s12915-020-0738-1

| The page says | The source says |
| :--- | :--- |
| Farms and backyard flocks | More than 65 billion chickens are raised annually to produce meat and 80 million metric tons of egg for global human consumption by the commercial sector (note: stats.habitat: farm-scale keeping) |
| Chickens now live in backyard flocks and on farms, and a 2020 study put the commercial sector at more than 65 billion raised each year for meat. | More than 65 billion chickens are raised annually to produce meat and 80 million metric tons of egg for global human consumption by the commercial sector (note: 2020 is the reference's publication year; backyard flocks and farms carried by the ohio-4h-poultry claims below) |