Jump to content

Chicken: Difference between revisions

From Wikipedia, the free encyclopedia
Content deleted Content added
No edit summary
Description: broiler line
 
Line 1: Line 1:
{{Short description|Domesticated species of bird}}
{{otheruses}}
{{About||the culinary use of chickens|Chicken as food|other uses|Chicken (disambiguation)}}
{{Taxobox|name=Chicken|color=pink
{{Redirect2|Rooster|Roosters}}
|status={{StatusDomesticated}}
{{Redirect|Cockerel|the Fabergé egg|Cockerel (Fabergé egg)}}
|image=Bantam_Rooster.jpg
{{Pp-move}}
|image_width=200px
{{Pp|small=yes}}
|image_caption=A Bantam rooster
{{Good article}}
|regnum=[[Animal]]ia
{{Use mdy dates|date=September 2023}}
|phylum = [[Chordate|Chordata]]
{{Speciesbox
|classis = [[Bird|Aves]]
| image = Male and female chicken sitting together.jpg
|ordo=[[Galliformes]]
| image_caption = Male (left) and female (right)
|familia=[[Phasianidae]]
| status = DOM
|genus=''[[Junglefowl|Gallus]]''
| genus = Gallus
|species=''[[Red Junglefowl|G. gallus]]''
|subspecies='''''G. g. domesticus'''''
| species = gallus domesticus
| synonyms = ''Gallus domesticus'' <small>[[L.]]</small>
|trinomial=''Gallus gallus domesticis''|author=[[Marvin Linnaeus|Linnaeus]]|date = [[1758]]
| authority = ([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])
| range_map = GLW 2 global distributions of c) chickens.tif
| range_map_caption = Chicken distribution
}}
}}
The '''chicken''' ('''''Gallus domesticus''''') is a large and round short-winged [[bird]], [[domestication|domesticated]] from the [[red junglefowl]] of [[Southeast Asia]] around 8,000 years ago. Most chickens are raised for food, providing [[Chicken as food|meat]] and [[egg as food|eggs]]; others are kept as [[pet]]s<ref>{{Cite web |last=Joshua |date=2020-07-27 |title=Chickens and Roosters…As Pets? |url=https://journal.iaabcfoundation.org/roosters-as-pets/ |access-date=2024-12-05 |website=IAABC Foundation Journal}}</ref> or for [[cockfight]]ing.


Chickens are common and widespread domestic animals, with a total population of 26.5 billion {{As of|2023|lc=y}}, and an annual production of more than 50 billion birds. A hen bred for laying can produce over 300 eggs per year. There are numerous [[cultural references to chickens]] in folklore, religion, and literature.
A '''chicken''' (''Gallus gallus domesticis'') is a type of [[domestication|domesticated]] [[farmer's pet]] which is often raised as a type of [[poultry]]. It is believed to be descended from the wild Indian and south-east Asian [[Gray Junglefowl]].


== Nomenclature ==
With a population of more than 24 billion in 2003 (according to the ''Firefly Encyclopedia of Birds''), there are more chickens in the world than any other bird. They provide two sources of food frequently consumed by humans: their [[Chicken (food)|meat]], also known as chicken, and [[egg (food)|eggs]].


Terms for chickens include:
==General biology and habitat==
[[Image:chicken's egg.jpg|thumb|250px|Chicken [[egg (food)|eggs]] vary in color depending on the hen, typically ranging from bright white to shades of brown and even blue, green, and recently reported purple (found in South Asia) (Araucana varieties).]]
[[Image:Rooster crowing.jpg|thumb|250px|Rooster crowing during daylight hours]]


* ''Biddy'': a chicken, or a newly hatched chicken<ref>{{cite web |url=https://www.dictionary.com/browse/biddy |title=Definition of biddy |publisher=Dictionary.com |access-date=May 7, 2021 |archive-date=May 7, 2021 |archive-url=https://web.archive.org/web/20210507151125/https://www.dictionary.com/browse/biddy |url-status=live}}</ref><ref>{{cite web |url=https://www.collinsdictionary.com/us/dictionary/english/biddy |title=Biddy definition and meaning |publisher=Collins English Dictionary|access-date=May 7, 2021 |archive-date=May 7, 2021 |archive-url=https://web.archive.org/web/20210507010137/https://www.collinsdictionary.com/us/dictionary/english/biddy |url-status=live}}</ref>
Male chickens are known as [[rooster]]s (in the U.S., Canada and Australia), cocks, or cockerels if they are young. Female chickens are known as hens, or 'chooks' in Australasian English. Young females are known as [[pullet]]s. Roosters can usually be differentiated from hens by their striking plumage, marked by long flowing tails and bright pointed feathers on their necks.
* ''[[Capon]]'': a castrated or [[neutered]] male chicken{{efn|The surgical and chemical castration of chickens is now illegal in some parts of the world.}}
* ''[[Chick (young bird)|Chick]]'': a young chicken<ref>{{cite web |title=Chick |url=https://dictionary.cambridge.org/us/dictionary/english/chick |url-status=live |publisher=Cambridge Dictionary |archive-url=https://web.archive.org/web/20150907132725/http://dictionary.cambridge.org/us/dictionary/english/chick |archive-date=September 7, 2015 }}</ref>
* ''Chook'' {{IPAc-en|tʃ|ʊ|k}}: a chicken (Australia/New Zealand, informal)<ref>{{cite web |title=Chook |url=https://dictionary.cambridge.org/us/dictionary/english/chook |url-status=live |access-date=March 4, 2021 |website=Cambridge Dictionary |archive-url=https://web.archive.org/web/20150907151220/http://dictionary.cambridge.org/us/dictionary/english/chook |archive-date=September 7, 2015 }}</ref>
* ''Cock'': a fertile adult male chicken<ref>{{cite web |title=Cock |url=https://dictionary.cambridge.org/us/dictionary/english/cock |url-status=live |access-date=March 4, 2021 |publisher=Cambridge Dictionary |archive-url=https://web.archive.org/web/20150907102240/http://dictionary.cambridge.org/us/dictionary/english/cock |archive-date=September 7, 2015 }}</ref><ref>{{Cite web |title=Hen |url=https://dictionary.cambridge.org/us/dictionary/english/cock |url-status=live |access-date=March 4, 2021 |publisher=Cambridge Dictionary |archive-url=https://web.archive.org/web/20150907102240/http://dictionary.cambridge.org/us/dictionary/english/cock |archive-date=September 7, 2015 }}</ref>
* ''Cockerel'': a young male chicken<ref>{{cite encyclopedia |url=http://dictionary.reference.com/browse/cockerel |title=Cockerel |publisher=Dictionary Reference |access-date=August 29, 2010 |archive-url=https://web.archive.org/web/20160307191527/http://dictionary.reference.com/browse/cockerel |archive-date=March 7, 2016 |url-status=live }}</ref>
* ''Hen'': an adult female chicken<ref>{{cite web |title=Hen noun |url=https://www.merriam-webster.com/dictionary/hen |publisher=[[Merriam-Webster]] |access-date=2 February 2024}}</ref>
* ''Pullet'': a young female chicken less than a year old.<ref>{{cite encyclopedia |url=http://dictionary.reference.com/browse/pullet |title=Pullet |publisher=Dictionary Reference |access-date=August 29, 2010 |archive-url=https://web.archive.org/web/20101109014624/http://dictionary.reference.com/browse/pullet |archive-date=November 9, 2010 |url-status=live }}</ref> In the poultry industry, a pullet is a sexually immature chicken less than 22 weeks of age.<ref>{{Cite web |title=Overview of the Poultry Industry |url=https://dese.mo.gov/sites/default/files/aged%20-PoultrySR.pdf |url-status=live |publisher=Missouri Department of Elementary and Secondary Education |page=8 |archive-url=https://web.archive.org/web/20201023230530/https://dese.mo.gov/sites/default/files/aged%20-PoultrySR.pdf |archive-date=October 23, 2020 }}</ref>
* ''Rooster'': a fertile adult male chicken, especially in North America. Originated in the 18th century, possibly as a euphemism to avoid the sexual connotation of the word ''cock''.<ref>{{Cite web |title=Definition of Rooster |url=https://www.merriam-webster.com/dictionary/rooster |publisher=Merriam-Webster |access-date=March 6, 2021 |archive-date=April 22, 2021 |archive-url=https://web.archive.org/web/20210422030634/https://www.merriam-webster.com/dictionary/rooster |url-status=live}}</ref><ref name="Rawson">[http://www.americanheritage.com/content/why-do-we-say-17 Hugh Rawson] {{Webarchive |url=https://web.archive.org/web/20170701144833/http://www.americanheritage.com/content/why-do-we-say-17 |date=July 1, 2017 }} "Why Do We Say...? Rooster", ''American Heritage'', August–September 2006.</ref><ref name="Online Etymology Dictionary">[https://www.etymonline.com/search?q=rooster Online Etymology Dictionary] {{Webarchive |url=https://web.archive.org/web/20201111222713/https://www.etymonline.com/search?q=rooster |date=November 11, 2020 }} Entry for ''rooster (n.)'', May 2019</ref>
* ''Yardbird'': a chicken (southern United States, dialectal)<ref name="berhardt">{{cite book |last=Berhardt |first=Clyde E. B. |title=I Remember: Eighty Years of Black Entertainment, Big Bands |year=1986 |publisher=[[University of Pennsylvania Press]] |isbn=978-0-8122-8018-0 |oclc=12805260 |page=153}}</ref>


''Chicken'' can mean a ''chick'', as in [[William Shakespeare]]'s play ''[[Macbeth]]'', where [[Macduff (Macbeth)|Macduff]] laments the death of "all my pretty chickens and their dam".<ref>[[William Shakespeare|Shakespeare, William]], ''[[Macbeth]]'', Act 4 Scene 3, lines 217–229.</ref> The usage is preserved in placenames such as the [[Hen and Chicken Islands]].<ref>{{Cite web |title=Chicken |url=https://www.merriam-webster.com/dictionary/chicken |url-status=live |access-date=March 4, 2021 |website=Merriam Webster Dictionary |archive-url=https://web.archive.org/web/20080821163810/http://www.merriam-webster.com/dictionary/chicken |archive-date=August 21, 2008 }}</ref> In older sources, and still often in trade and scientific contexts, chickens as a species are described as ''common fowl'' or ''domestic fowl''.<ref>{{cite book |last=Stevens |first=Lewis |title=Genetics and evolution of the domestic fowl |pages=11 and throughout |year=1991 |publisher=[[Cambridge University Press]] |isbn=978-0-521-40317-7 |url=https://books.google.com/books?id=S-DXqQ9UOmAC&dq=%22domestic+fowl%22&pg=PA11}}</ref>
However, in some breeds, such as the Sebright, the cock only has slightly pointed neck feathers, and the identification must be made by looking at the comb. Chickens have a fleshy crest on their heads called a comb, and a fleshy piece of hanging skin under their beak called a wattle. These organs help to cool the bird by redirecting bloodflow to the skin. Both the male and female have distinctive wattles and combs. In males, the combs are often more prominent, though this is not the case in all varieties.


== Description ==
Domestic chickens are typically fed commercially prepared feed that includes a [[protein]] source as well as [[Cereal|grain]]s. Chickens often scratch at the soil to get at adult insects and larvae or seed. Incidents of [[cannibalism]] can occur when a curious bird pecks at a pre-existing wound or during fighting (even among female birds). This is exacerbated in close quarters. In commercial egg production this is controlled by trimming the beak (removal of ⅔ of the top half and occasionally ⅓ of the lower half of the beak).


{{multiple image
Domestic chickens are not capable of flying for long distances, although they are generally capable of flying for short distances such as over fences. Chickens will sometimes fly simply in order to explore their surroundings, but will especially fly in an attempt to flee when they perceive danger. Because of the risk of flight, chickens raised in the open air generally have one of their wings clipped by the breeder &mdash; the tips of the longest feathers on one of the wings are cut, resulting in unbalanced flight which the bird cannot sustain for more than a few meters ([http://www.omlet.co.uk/chickenguide/guide.php?cat_selected=Chicken%20Care&sub_selected=wing%20clipping more on wing clipping]).
| width1 = 150
| image1 = Rooster portrait2.jpg
| caption1 = [[Comb (anatomy)|Comb]] of male
| width2 = 200
| image2 = Hen Comb (cropped).jpg
| caption2 = Comb of female, generally smaller
}}

Chickens are relatively large [[bird]]s, [[Diurnality|active by day]]. The body is round, the legs are unfeathered in most breeds, and the wings are short.<ref name="Smithsonian"/> Wild [[junglefowl]] can [[bird flight|fly]]; chickens and their [[flight muscle]]s are too heavy to allow them to fly more than a short distance.<ref>{{cite web |last1=Geggel |first1=Laura |title=Forget About the Road. Why Are Chickens So Bad at Flying? |url=https://www.livescience.com/57139-why-chickens-cannot-fly.html |website=Live Science |access-date=3 February 2024 |date=8 December 2016 |archive-date=April 4, 2024 |archive-url=https://web.archive.org/web/20240404115622/https://www.livescience.com/57139-why-chickens-cannot-fly.html |url-status=live }}</ref> Size and coloration vary widely between breeds.<ref name="Smithsonian">{{cite web |title=Chicken |url=https://nationalzoo.si.edu/animals/domestic-chicken |publisher=Smithsonian's National Zoo & Conservation Biology Institute |access-date=2 February 2024 |archive-date=February 2, 2024 |archive-url=https://web.archive.org/web/20240202165324/https://nationalzoo.si.edu/animals/domestic-chicken |url-status=live }}</ref> Newly-hatched chicks of both modern and heritage varieties weigh the same, about {{cvt|37|g|oz}}. Modern varieties however grow much faster; by day 35 a Ross 708 [[broiler]] may weigh {{cvt|1.8|kg|lb}} as against the {{cvt|1.05|kg|lb}} of a heritage chicken of the same age.<ref name="Schmidt Persia 2009">{{cite journal |last=Schmidt |first=C.J. |last2=Persia |first2=M.E. |last3=Feierstein |first3=E. |last4=Kingham |first4=B. |last5=Saylor |first5=W.W. |title=Comparison of a modern broiler line and a heritage line unselected since the 1950s |journal=Poultry Science |volume=88 |issue=12 |date=2009 |doi=10.3382/ps.2009-00055 |doi-access=free |pages=2610–2619}}</ref>

Adult chickens of both sexes have a fleshy crest on their heads called a comb or cockscomb, and hanging flaps of skin on either side under their beaks called [[Wattle (anatomy)|wattles]]; combs and wattles are [[Sexual dimorphism|more prominent in males]]. Some breeds have a [[mutation]] that causes extra feathering under the face, giving the appearance of a beard.<ref name=plosg>{{cite journal |last1=Guo |first1=Ying |last2=Gu |first2=Xiaorong |last3=Sheng |first3=Zheya |last4=Wang |first4=Yanqiang |last5=Luo |first5=Chenglong |last6=Liu |first6=Ranran |last7=Qu |first7=Hao |last8=Shu |first8=Dingming |last9=Wen |first9=Jie |last10=Crooijmans |first10=Richard P. M. A. |last11=Carlborg |first11=Örjan |last12=Zhao |first12=Yiqiang |last13=Hu |first13=Xiaoxiang |last14=Li |first14=Ning |display-authors=5 |title=A Complex Structural Variation on Chromosome 27 Leads to the Ectopic Expression of HOXB8 and the Muffs and Beard Phenotype in Chickens |journal=PLOS Genetics |volume=12 |issue=6 |date=2 June 2016 |pmid=27253709 |pmc=4890787 |doi=10.1371/journal.pgen.1006071 |doi-access=free |page=e1006071}}</ref>


Chickens are [[omnivore]]s.<ref>{{cite web |url=http://www.ideas-4-pets.co.uk/info.-on-chicken-care |title=Info on Chicken Care |access-date=August 13, 2008 |website=Ideas-4-pets.co.uk |year=2003 |archive-url=https://web.archive.org/web/20150625195044/http://www.ideas-4-pets.co.uk/info.-on-chicken-care |archive-date=June 25, 2015 |url-status=dead }}</ref> In the wild, they scratch at the soil to search for seeds, insects, and animals as large as [[lizard]]s, small snakes,<ref>{{cite web |url=https://www.youtube.com/watch?v=45i1hZfUQhk |archive-url=https://ghostarchive.org/varchive/youtube/20211211/45i1hZfUQhk| archive-date=December 11, 2021 |url-status=live|title=Chicken Kills Rattlesnake |last=D Lines |date=July 27, 2013 |access-date=March 13, 2019 |publisher=[[YouTube]]}}{{cbignore}}</ref> and young [[mouse|mice]].<ref>{{cite web |url=https://gworrell.freeyellow.com/chickenfaq.html |title=Frequently asked questions about chickens & eggs |access-date=August 13, 2008 |website=Gworrell.freeyellow.com |author=Gerard P.Worrell AKA "Farmer Jerry" |archive-url=https://web.archive.org/web/20080916202420/http://gworrell.freeyellow.com/chickenfaq.html |archive-date=September 16, 2008 |url-status=live }}</ref> A chicken may live for 5–10 years, depending on the [[breed]].<ref>{{cite web |url=http://www.ruleworks.co.uk/cgi-bin/TUfaq.exe?Guide=Poultry&Category=Poultry%20-%20General#q9 |title=The Poultry Guide – A to Z and FAQs |website=Ruleworks.co.uk |access-date=August 29, 2010 |archive-url=https://web.archive.org/web/20101128085141/http://ruleworks.co.uk/cgi-bin/TUfaq.exe?Guide=Poultry&Category=Poultry%20-%20General#q9 |archive-date=November 28, 2010 |url-status=dead }}</ref> The world's oldest known chicken lived for 16 years.<ref>{{cite web|last1=Smith |first1=Jamon |url=https://www.tuscaloosanews.com/article/DA/20060806/News/606120381/TL |title=World's oldest chicken starred in magic shows, was on 'Tonight Show' |archive-url=https://web.archive.org/web/20190220002804/https://www.tuscaloosanews.com/apps/pbcs.dll/article?AID=%2F20060806%2FNEWS%2F608060400%2F1007%2FNEWS02 |archive-date=February 20, 2019 |website=[[Tuscaloosa News]] |location=Alabama, USA |date=August 6, 2006 |access-date=May 18, 2020 |url-status=live}}</ref>
Chickens are gregarious birds and live together as a [[herd|flock]]. They have a communal approach to the [[avian incubation|incubation]] of eggs and raising of young. Individual chickens in a flock will dominate others, establishing a "[[pecking order]]", with dominant individuals having priority for access to food and nesting locations. Removing hens or roosters from a flock causes a temporary disruption to this social order until a new pecking order is established.


Chickens are [[gregarious]], living in [[herd|flocks]], and [[Egg incubation|incubate eggs]] and raise young communally. Individual chickens dominate others, establishing a [[Dominance hierarchy|pecking order]]; dominant individuals take priority for access to food and nest sites. The concept of dominance, involving pecking, was described in female chickens by [[Thorleif Schjelderup-Ebbe]] in 1921 as the "pecking order".<ref>{{cite journal |last=Perrin |first=P. G. |year=1955 |title='Pecking order' 1927–54 |journal=American Speech |volume=30 |issue=4 |pages=265–268|doi=10.2307/453561 |jstor=453561 | issn = 0003-1283}}</ref><ref>{{cite book |last=Schjelderup-Ebbe |first=T. |year=1975 |chapter=Contributions to the social psychology of the domestic chicken [Schleidt M., Schleidt, W. M., translators] |editor-last=Schein |editor-first=M. W. |title=Social Hierarchy and Dominance. Benchmark Papers in Animal Behavior |volume=3 |location=Stroudsburg, Pennsylvania |publisher=Dowden, Hutchinson and Ross |pages=35–49}} (Reprinted from ''Zeitschrift für Psychologie'', 1922, 88:225–252.)</ref> Male chickens tend to leap and use their claws in conflicts.<ref>{{cite journal |last=Rajecki |first=D. W. |year=1988 |title=Formation of leap orders in pairs of male domestic chickens |journal=Aggressive Behavior |volume=14 |issue=6 |pages=425–436|doi=10.1002/1098-2337(1988)14:6<425::AID-AB2480140604>3.0.CO;2-#|s2cid=141664966 }}</ref> Chickens are capable of mobbing and killing a weak or inexperienced predator, such as a young fox.<ref>{{cite web |last=AFP |date=March 12, 2019 |title=Chickens 'teamed up to kill fox' at Brittany farming school |url=https://www.theguardian.com/world/2019/mar/12/chickens-teamed-up-to-kill-fox-at-brittany-farming-school |url-status=live |archive-url=https://web.archive.org/web/20190313002528/https://www.theguardian.com/world/2019/mar/12/chickens-teamed-up-to-kill-fox-at-brittany-farming-school |archive-date=March 13, 2019 |access-date=March 13, 2019 |website=Theguardian.com}}</ref>
Chickens will try to lay in nests that already contain eggs, and have been known to move eggs from neighbouring nests into their own. Some farmers use fake eggs made from plastic or stone to encourage hens to lay in a particular location. The result of this behavior is that a flock will use only a few preferred locations, rather than having a different nest for every bird.


[[File:Rooster_crowing_small.ogv|thumb|Crowing (with audio)]]
Hens can also be extremely stubborn about always laying in the same location. It is not unknown for two (or more) hens to try to share the same nest at the same time. If the nest is small, or one of the hens is particularly determined, this may result in chickens trying to lay on top of each other.


A male's crowing is a loud and sometimes shrill call, serving as a territorial signal to other males,<ref>{{Cite news |url=https://phys.org/news/2015-07-cock-roosters-crow.html |title=Top cock: Roosters crow in pecking order |website=Phys.org |access-date=January 14, 2018 |archive-url=https://web.archive.org/web/20180115124738/https://phys.org/news/2015-07-cock-roosters-crow.html |archive-date=January 15, 2018 |url-status=live }}</ref> and in response to sudden disturbances within their surroundings. Hens cluck loudly after laying an [[egg]] and to call their chicks. Chickens give different [[warning call]]s to indicate that a [[Predation|predator]] is approaching from the air or on the ground.<ref>{{cite journal |last1=Evans |first1=Christopher S. |last2=Evans |first2=Linda |last3=Marler |first3=Peter |title=On the meaning of alarm calls: functional reference in an avian vocal system |journal=Animal Behaviour |date=July 1993 |volume=46 |issue=1 |pages=23–38 |doi=10.1006/anbe.1993.1158 |s2cid=53165305 |s2cid-access=free }}</ref>
Contrary to popular belief, roosters may crow at any time of the day or night. Their crowing - a loud and sometimes shrill call - is a territorial signal to other roosters. However, crowing may also result from sudden disturbances within their surroundings.


== Reproduction and life-cycle ==
Chickens are domesticated descendants of the [[red junglefowl]], which is biologically classified as the same species.


To initiate courting, some roosters may dance in a circle around or near a hen (a circle dance), often lowering the wing which is closest to the hen.<ref name="grandin69">{{cite book |title=Animals in Translation |last1=Grandin |first1=Temple |author-link1=Temple Grandin |last2=Johnson |first2=Catherine |year=2005 |publisher=[[Scribner's]] |location=New York City |isbn=978-0-7432-4769-6 |pages=[https://archive.org/details/animalsintransla00gran/page/69 69–71] |url-access=registration |url=https://archive.org/details/animalsintransla00gran/page/69 }}</ref> The dance triggers a response in the hen<ref name="grandin69" /> and when she responds to his call, the rooster may mount the hen and proceed with the mating. Mating typically involves a sequence in which the male approaches the female and performs a waltzing display. If the female is unreceptive, she runs off; otherwise, she crouches, and the male mounts, treading with both feet on her back. After copulation the male does a tail-bending display.<ref>{{cite journal |last1=Cheng |first1=Kimberly M. |last2=Burns |first2=Jeffrey T. |title=Dominance Relationship and Mating Behavior of Domestic Cocks: A Model to Study Mate-Guarding and Sperm Competition in Birds |journal=[[Ornithological Applications|The Condor]] |date=August 1988 |volume=90 |issue=3 |pages=697–704 |doi=10.2307/1368360 |jstor=1368360 }}</ref>
Recent studies [http://www.foxnews.com/story/0,2933,185704,00.html] have shown that chickens (and possibly other bird species) still retain the genetic blueprints to produce teeth in the jaws, although these are dormant in living animals. These are a holdover from primitive birds such as ''[[Archaeopteryx]]'', which were descended from [[theropoda|theropod]] [[dinosaur]]s.


Sperm transfer occurs by [[cloaca]]l contact between the male and female, in an action called the 'cloacal kiss'.<ref name="Briskie1997">{{cite journal |last=Briskie |first=J. V. |author2=R. Montgomerie |year=1997 |title=Sexual Selection and the Intromittent Organ of Birds |journal=Journal of Avian Biology |volume=28 |issue=1 |pages=73–86 |doi=10.2307/3677097 |jstor=3677097}}</ref> As with all birds, [[reproduction]] is controlled by a [[neuroendocrine cell|neuroendocrine]] system,<ref>{{Cite journal |last1=Dufour |first1=Sylvie |last2=Quérat |first2=Bruno |last3=Tostivint |first3=Hervé |last4=Pasqualini |first4=Catherine |last5=Vaudry |first5=Hubert |last6=Rousseau |first6=Karine |date=April 2020 |title=Origin and Evolution of the Neuroendocrine Control of Reproduction in Vertebrates, With Special Focus on Genome and Gene Duplications |url=https://journals.physiology.org/doi/full/10.1152/physrev.00009.2019 |journal=Physiological Reviews |volume=100 |issue=2 |pages=869–943 |doi=10.1152/physrev.00009.2019 |pmid=31625459 |issn=0031-9333}}</ref> the [[Gonadotropin-Releasing Hormone-I neuron]]s in the [[hypothalamus]]. Reproductive hormones including [[estrogen]], [[progesterone]], and [[gonadotropin]]s ([[luteinizing hormone]] and [[follicle-stimulating hormone]]) initiate and maintain sexual maturation changes. Reproduction declines with age, thought to be due to a decline in GnRH-I-N.<ref name="Bain-et-al-2016">{{cite journal |last1=Bain |first1=M. M. |last2=Nys |first2=Y. |last3=Dunn |first3=I.C. |title=Increasing persistency in lay and stabilising egg quality in longer laying cycles. What are the challenges? |journal=[[British Poultry Science]] |publisher=[[Taylor & Francis]] |volume=57 |issue=3 |date=May 3, 2016 |doi=10.1080/00071668.2016.1161727 |pages=330–338 |pmid=26982003 |pmc=4940894 |s2cid=17842329 |doi-access=free }}</ref>
== Courting ==
When a rooster finds food he may call the other chickens to eat it first. He does this by clucking in a high pitch as well as picking up and dropping the food. This behavior can also be observed in mother hens, calling their chicks. In some cases the rooster will drag the wing opposite the hen on the ground, while circling her. This is part of chicken courting ritual. When a hen is used to coming to his "call" the rooster may mount the hen and proceed with the fertilization.


[[File:Newly-hatched chickens.jpg|thumb|Newly hatched chicks]]
==Going broody==
[[Image:Broody hen.JPG|thumb|right|180px|A broody hen guarding her eggs]]
Sometimes a hen will stop laying and instead will focus on the incubation of eggs, a state that is commonly known as ''going broody''. A broody chicken will sit fast on the nest, and protest or peck in defense if disturbed or removed, and will rarely leave the nest to eat, drink, or dust bathe. While broody, the hen keeps the eggs at a constant temperature and humidity, as well as turning the eggs regularly.


Hens often try to lay in nests that already contain eggs and sometimes move eggs from neighbouring nests into their own. A flock thus uses only a few preferred locations, rather than having a different nest for every bird.<ref>{{cite journal |last1=Sherwin |first1=C.M. |last2=Nicol |first2=C.J. |year=1993 |title=Factors influencing floor-laying by hens in modified cages |journal=[[Applied Animal Behaviour Science]] |volume=36 |issue=2–3 |pages=211–222 |doi=10.1016/0168-1591(93)90011-d}}</ref> Under natural conditions, most birds lay only until a [[Clutch (eggs)|clutch]] is complete; they then incubate all the eggs. This is called "going [[Broodiness|broody]]". The hen sits on the nest, fluffing up or pecking defensively if disturbed. She rarely leaves the nest until the eggs have hatched.<ref name="Puff-up-Feathers">{{cite web |title=Why Do Chickens Puff up Their Feathers? I 4 Reasons Explained|date= August 8, 2020|url= https://chickenandchicksinfo.com/why-do-chickens-puff-up-their-feathers/ |access-date=June 16, 2021 |archive-date=June 18, 2021 |archive-url=https://web.archive.org/web/20210618091939/https://chickenandchicksinfo.com/why-do-chickens-puff-up-their-feathers/ |url-status=live}}</ref>
At the end of the incubation period, which is an average of 21 days, the eggs (if fertilized) will hatch, and the broody hen will take care of her young. Since individual eggs do not all hatch at exactly the same time (the chicken can only lay one egg approximately every 25 hours), the hen will usually stay on the nest for about two days after the first egg hatches. During this time, the newly-hatched chicks live off the egg yolk they absorb just before hatching. The hen can hear the chicks peeping inside the eggs, and will gently cluck to encourage them to break out of their shells. If the eggs are not fertilized and do not hatch, the hen will eventually grow tired of being broody and leave the nest.


Eggs of chickens from the high-altitude region of [[Tibet]] have special physiological adaptations that result in a higher hatching rate in low oxygen environments. When eggs are placed in a hypoxic environment, chicken embryos from these populations express much more [[hemoglobin]] than embryos from other chicken populations. This hemoglobin has a greater affinity for oxygen, binding oxygen more readily.<ref>{{Cite journal |last1=Zhang |first1=H. |last2=Wang |first2=X.T. |last3=Chamba |first3=Y. |last4=Ling |first4=Y.|last5=Wu|first5=C.X. |date=October 2008|title=Influences of Hypoxia on Hatching Performance in Chickens with Different Genetic Adaptation to High Altitude |journal=Poultry Science |volume=87 |issue=10 |pages=2112–2116 |doi=10.3382/ps.2008-00122 |pmid=18809874 |doi-access=free}}</ref>
Modern egg-laying breeds rarely go broody, and those that do often stop part-way through the incubation cycle. Some breeds, such as the [[Cochin (chicken)|Cochin]], [[Cornish (chicken)|Cornish]] and [[Silkie (chicken)|Silkie]], regularly go broody and make excellent mothers.


Fertile chicken eggs hatch at the end of the incubation period, about 21 days; the chick uses its [[egg tooth]] to break out of the shell.<ref name="grandin69"/> Hens remain on the nest for about two days after the first chick hatches; during this time the newly hatched chicks feed by absorbing the internal [[yolk sac]].<ref>{{cite journal |last1=Ali |first1=A. |last2=Cheng |first2=K.M. |year=1985 |title=Early egg production in genetically blind (rc/rc) chickens in comparison with sighted (Rc+/rc) controls |journal=Poultry Science |volume=64 |issue=5 |pages=789–794 |doi=10.3382/ps.0640789 |pmid=4001066 |doi-access=free }}</ref> The hen guards her chicks and broods them to keep them warm. She leads them to food and water and calls them towards food. The chicks [[Imprinting (psychology)|imprint]] on the hen and subsequently follow her continually. She continues to care for them until they are several weeks old.<ref name="Edgar Held Jones Troisi 2016 p. 2">{{cite journal |last1=Edgar |first1=Joanne |last2=Held |first2=Suzanne |last3=Jones |first3=Charlotte |last4=Troisi |first4=Camille |title=Influences of Maternal Care on Chicken Welfare |journal=Animals |volume=6 |issue=1 |date=2016-01-05 |pmid=26742081 |pmc=4730119 |doi=10.3390/ani6010002 |doi-access=free |page=2}}</ref>
==Artificial incubation==
Chicken egg incubation can successfully occur artificially as well. Nearly all chicken eggs will hatch after 21 days of good conditions - 99.5° [[fahrenheit]] (37.5°[[Celsius|C]]) and around 55% [[relative humidity]] (increase to 70% in the last three days of incubation to help soften egg shell). Many commercial incubators are industrial-sized with shelves holding tens of thousands of eggs at a time, with rotation of the eggs a fully automated process.


Inbreeding of White Leghorn chickens tends to cause [[inbreeding depression]] expressed as reduced egg number and delayed sexual maturity.<ref>{{cite journal |last1=Sewalem |first1=A. |last2=Johansson |first2=K. |last3=Wilhelmson |first3=M. |last4=Lillpers |first4=K. |title=Inbreeding and inbreeding depression on reproduction and production traits of White Leghorn lines selected for egg production traits |journal=British Poultry Science |volume=40 |issue=2 |date=1999 |doi=10.1080/00071669987601 |pages=203–208|pmid=10465386 }}</ref> Strongly inbred Langshan chickens display obvious inbreeding depression in reproduction, particularly for traits such as age when the first egg is laid and egg number.<ref>{{cite journal |last1=Xue |first1=Qian |last2=Li |first2=Guohui |last3=Cao |first3=Yuxia |last4=Yin |first4=Jianmei |last5=Zhu |first5=Yunfen |last6=Zhang |first6=Huiyong |last7=Zhou |first7=Chenghao |last8=Shen |first8=Haiyu |last9=Dou |first9=Xinhong |last10=Su |first10=Yijun |last11=Wang |first11=Kehua |last12=Zou |first12=Jianmin |last13=Han |first13=Wei |title=Identification of genes involved in inbreeding depression of reproduction in Langshan chickens |journal=Animal Bioscience |volume=34 |issue=6 |date=1 June 2021 |issn=2765-0189 |pmid=33152217 |pmc=8100482 |doi=10.5713/ajas.20.0248 |pages=975–984}}</ref>
Home incubators are usually small boxes ([[styrofoam]] incubators are popular) and hold a few to 50 eggs. Eggs must be turned three to five times each day, rotating at least 90 degrees. If eggs aren't turned, the [[embryo]] inside will stick to the shell and likely will be hatched with physical defects. This process is natural; hens will stand up three to five times a day and shift the eggs around with their [[beak]].


==Chickens as food==
== Origin ==
<!--PLEASE stop squashing everything up, spaces and blank lines are intentional, THANK YOU-->
{{main|Chicken (food)}}


==Chickens as pets==
=== Phylogeny ===
[[Image:Day_old_chick02.jpg|thumb|300px|right|pair of day old chicks]]
Chickens can make loving and gentle companion animals, but sometimes can turn nasty. It is not suggested you keep a chicken as a pet if you have young children, as they can be very territorial and violent. In [[Asia]], chickens with striking plumage have long been kept for ornamental purposes, including feather-footed varieties such as the [[Cochin (chicken)|Cochin]] and [[Silkie]] from [[China]] and the extremely long-tailed [[Phoenix (chicken)|Phoenix]] from [[Japan]]. Asian ornamental varieties were imported into the [[United States]] and [[Great Britain]] in the late 1800s. Poultry fanciers then began keeping these ornamental birds for exhibition, a practice that continues today. From these Asian breeds, distinctive American varieties of chickens have been developed.


[[File:Red Junglefowl.jpg|thumb|[[Red junglefowl]], the wild ancestor of the chicken ]]
Today, some cities in the United States still allow residents to keep chickens as pets, although the practice is quickly disappearing. Individuals in rural communities commonly keep chickens for both ornamental and practical value. Some communities ban only roosters, allowing the quieter hens. Many zoos use chickens instead of [[insecticide]]s to control insect populations.


Water or ground-dwelling fowl similar to modern [[partridge]]s, in the [[Galliformes]], the [[order (biology)|order]] of bird that chickens belong to, survived the [[Cretaceous–Paleogene extinction event]] that killed all tree-dwelling birds and their [[dinosaur]] relatives.<ref>{{cite journal |last=Pennisi |first=Elizabeth |author-link=Elizabeth Pennisi |title=Quaillike creatures were the only birds to survive the dinosaur-killing asteroid impact |journal=Science |date=May 24, 2018 |doi=10.1126/science.aau2802}}</ref> Chickens are descended primarily from the [[red junglefowl]] (''Gallus gallus'') and are scientifically classified as the same species.<ref name=nature>{{cite journal |title=A genetic variation map for chicken with 2.8 million single nucleotide polymorphisms |journal=Nature |date=December 9, 2004 |volume=432 |issue=7018 |pages=717–722 |doi=10.1038/nature03156 |pmid=15592405 |pmc=2263125 |bibcode=2004Natur.432..717B |last1=Wong |first1=G. K. |last2=Liu |first2=B. |last3=Wang |first3=J. |last4=Zhang |first4=Y. |last5=Yang |first5=X. |last6=Zhang |first6=Z. |last7=Meng |first7=Q. |last8=Zhou |first8=J. |last9=Li |first9=D. |last10=Zhang |first10=J. |last11=Ni |first11=P. |last12=Li |first12=S. |display-authors=6}}</ref> Domesticated chickens freely interbreed with populations of red junglefowl.<ref name=nature /> The domestic chicken has subsequently hybridised with [[grey junglefowl]], [[Sri Lankan junglefowl]] and [[green junglefowl]];<ref name="Lawal">{{cite journal |last1=Lawal |first1=Raman Akinyanju |last2=Martin |first2=Simon H. |last3=Vanmechelen |first3=Koen |last4=Vereijken |first4=Addie |last5=Silva |first5=Pradeepa |last6=Al-Atiyat |first6=Raed Mahmoud |last7=Aljumaah |first7=Riyadh Salah |last8=Mwacharo |first8=Joram M. |last9=Wu |first9=Dong-Dong |last10=Zhang |first10=Ya-Ping |last11=Hocking |first11=Paul M. |last12=Smith |first12=Jacqueline |last13=Wragg |first13=David |last14=Hanotte |first14=Olivier |display-authors=6 |title=The wild species genome ancestry of domestic chickens |journal=BMC Biology |date=December 2020 |volume=18 |issue=1 |pages=13 |doi=10.1186/s12915-020-0738-1 |pmid=32050971 |pmc=7014787 |doi-access=free}}</ref> a gene for yellow skin, for instance, was incorporated into domestic birds from the grey junglefowl (''G. sonneratii'').<ref>{{cite journal |last1=Eriksson |first1=Jonas |last2=Larson |first2=Greger |last3=Gunnarsson |first3=Ulrika |last4=Bed'hom |first4=Bertrand |last5=Tixier-Boichard |first5=Michele |last6=Strömstedt |first6=Lina |last7=Wright |first7=Dominic |last8=Jungerius |first8=Annemieke |last9=Vereijken |first9=Addie |last10=Randi |first10=Ettore |last11=Jensen |first11=Per |last12=Andersson |first12=Leif |display-authors=6 |title=Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken |journal=PLOS Genetics |date=February 29, 2008 |volume=4 |issue=2 |pages=e1000010 |doi=10.1371/journal.pgen.1000010 |pmid=18454198 |pmc=2265484 |doi-access=free }}</ref> It is estimated that chickens share between 71 and 79% of their genome with red junglefowl.<ref name="Lawal"/>
Keeping a few chickens as backyard pets is surprisingly easy to do. The major challenge is protecting the birds from predators, both domestic predators such as dogs and wild predators such as racoons in North America and foxes in Europe. The birds will need a secure place to sleep at night. This can be as simple or as elaborate as you like. For only a few birds which are allowed to free roam during the day, a large dog house type structure with a locking door will serve just fine. Some kind of bedding such as straw or wood shaving should be provided on the floor. Nest boxes will make egg collection easier. If the birds are left in the structure during the day, a larger more elaborate structure would be necessary.


=== Domestication ===
Chicken naturally return to the same spot to roost everynight. That means on most occasions they will put themselves to bed and your only job is to make sure the door is shut and locked before nightfall. It is best to count the birds each night as sometimes a bird will not find her way back into the coop. A bird left out at night is likely to be taken by a racoon or other nocturnal predator.


{{further|Domestication}}
Most chickens cannot fly well and are easily contained with 3-4' fencing. Birds which are allowed to roam the yard during the day are quite effective at controlling insects of all types. The birds will pick at plants and grass and may cause some damage to ground-covers with their scratching. Areas of bare dirt will benefit from the weed control and soil cultivation provided by the birds in their never ending search for food. Also chickens will eat most any kind of food scraps. It can be quite satisfying to see unusable food items turned into eggs by these able recyclers.


[[File:Chicken domestication and dispersal.svg|thumb|upright=2|Chicken domestication and dispersal;<ref name="Lawal"/> possibility of early arrival in Americas<ref name="Borrell 2007"/><ref name="Storey 2007"/>]]
The eggs themselves can be quite different from the store purchased variety. Fresh yolks are quite "perky" and stand tall above the white. The yolk color is frequently a deeper color than the pale yellow of commercially raised eggs and can at time be almost a dark orange. The pleasure of picking up a freshly laid egg still warm to the touch is not to be overlooked.


According to one early study, a single domestication event of the [[red junglefowl]] in present-day [[Thailand]] gave rise to the modern chicken with minor transitions separating the modern breeds.<ref name="oneMatriarch">{{citation |title=One subspecies of the red junglefowl (Gallus gallus gallus) suffices as the matriarchic ancestor of all domestic breeds |first1=A. |last1=Fumihito |first2=T. |last2=Miyake |first3=S. |last3=Sumi |first4=M. |last4=Takada |first5=S. |last5=Ohno |first6=N. |last6=Kondo |journal=PNAS |date=December 20, 1994 |volume=91 |number=26 |pages=12505–12509 |doi=10.1073/pnas.91.26.12505 |pmid=7809067 |bibcode=1994PNAS...9112505F |pmc=45467 |doi-access=free }}</ref> The red junglefowl is well adapted to take advantage of the vast quantities of seed produced during the end of the [[Bamboo#Mass flowering|multi-decade bamboo seeding cycle]], to boost its own reproduction.<ref>{{citation |first=Rick |last=King |title=Rat Attack |date=February 24, 2009 |journal=Nova and National Geographic Television |url=https://www.pbs.org/wgbh/nova/nature/rat-attack.html |access-date=August 25, 2017 |archive-url=https://web.archive.org/web/20170823151419/http://www.pbs.org/wgbh/nova/nature/rat-attack.html |archive-date=August 23, 2017 |url-status=live }}</ref> In domesticating the chicken, humans took advantage of the red junglefowl's ability to reproduce prolifically when exposed to a surge in its food supply.<ref>{{citation |first=Rick |last=King |title=Plant vs. Predator |date=February 1, 2009 |journal=NOVA |url=https://www.pbs.org/wgbh/nova/nature/plant-vs-predator.html |access-date=August 25, 2017 |archive-url=https://web.archive.org/web/20170821123509/http://www.pbs.org/wgbh/nova/nature/plant-vs-predator.html |archive-date=August 21, 2017 |url-status=live }}</ref>
Growing chickens can easily be tamed by feeding them a special treat such as [[mealworm]]s in the palm of one's hand, and by being with them for at least ten minutes daily when they are young. However even older birds can be tamed considerably by hand feeding leftover table scraps to the birds. It can be fun to help the birds forage by turning rocks over and watching them grab worms and bugs that typically can be found in these dark, moist areas. The chickens quickly associate you with a source of food and will become your constant companion when you are both in the yard.


Exactly when and where the chicken was domesticated remains controversial. Genomic studies estimate that the chicken was domesticated 8,000 years ago<ref name="Lawal"/> in Southeast Asia and spread to China and India 2,000 to 3,000 years later. Archaeological evidence supports domestic chickens in Southeast Asia well before 6000&nbsp;BC, China by 6000&nbsp;BC and India by 2000&nbsp;BC.<ref name=Lawal/><ref name="West Zhou 1988">{{cite journal |last1=West |first1=B. |last2=Zhou |first2=B.X. |year=1988 |title=Did chickens go north? New evidence for domestication |journal=J. Archaeol. Sci. |volume=14 |issue= 5 |pages=515–533 |doi=10.1016/0305-4403(88)90080-5 |bibcode=1988JArSc..15..515W }}</ref><ref>{{cite journal |last1=Al-Nasser |first1=A. |last2=Al-Khalaifa |first2=H. |last3=Al-Saffar |first3=A. |last4=Khalil |first4=F. |last5=Albahouh |first5=M. |last6=Ragheb |first6=G. |last7=Al-Haddad |first7=A. |last8=Mashaly |first8=M. |title=Overview of chicken taxonomy and domestication |journal=World's Poultry Science Journal |date=June 1, 2007 |volume=63 |issue=2 |pages=285–300 |doi=10.1017/S004393390700147X |s2cid=86734013 }}</ref> A landmark 2020 Nature study that fully sequenced 863 chickens across the world suggests that all domestic chickens originate from a single domestication event of red junglefowl whose present-day distribution is predominantly in southwestern China, northern Thailand and Myanmar. These domesticated chickens spread across Southeast and South Asia where they interbred with local wild species of junglefowl, forming genetically and geographically distinct groups. Analysis of the most popular commercial breed shows that the White Leghorn breed possesses a mosaic of divergent ancestries inherited from subspecies of red junglefowl.<ref>{{cite journal |title=863 genomes reveal the origin and domestication of chicken |year=2020 |doi=10.1038/s41422-020-0349-y |s2cid=220050312 |last1=Wang |first1=Ming-Shan |last2=Thakur|first2=Mukesh |last3=Peng |first3=Min-Sheng |last4=Jiang |first4=Yu |last5=Frantz |first5=Laurent Alain François |last6=Li|first6=Ming |last7=Zhang|first7=Jin-Jin |last8=Wang |first8=Sheng |last9=Peters |first9=Joris |last10=Otecko |first10=Newton Otieno |last11=Suwannapoom |first11=Chatmongkon |last12=Guo |first12=Xing |journal=Cell Research |volume=30 |issue=8 |pages=693–701 |pmid=32581344 |pmc=7395088 |display-authors=6}}</ref><ref>{{cite journal |last1=Liu |first1=Yi-Ping |last2=Wu |first2=Gui-Sheng |last3=Yao |first3=Yong-Gang |last4=Miao |first4=Yong-Wang |last5=Luikart |first5=Gordon |last6=Baig |first6=Mumtaz |last7=Beja-Pereira |first7=Albano |last8=Ding |first8=Zhao-Li |last9=Palanichamy |first9=Malliya Gounder |last10=Zhang |first10=Ya-Ping |display-authors=6 |title=Multiple maternal origins of chickens: Out of the Asian jungles |journal=Molecular Phylogenetics and Evolution |date=January 2006 |volume=38 |issue=1 |pages=12–19 |doi=10.1016/j.ympev.2005.09.014 |pmid=16275023 |bibcode=2006MolPE..38...12L }}</ref><ref>{{cite journal |last1=Zeder |first1=Melinda A. |last2=Emshwiller |first2=Eve |last3=Smith |first3=Bruce D. |last4=Bradley |first4=Daniel G. |title=Documenting domestication: the intersection of genetics and archaeology |journal=Trends in Genetics |date=March 2006 |volume=22 |issue=3 |pages=139–155 |doi=10.1016/j.tig.2006.01.007 |pmid=16458995 }}</ref>
A former recurring [[sketch comedy|skit]] on the weekly comedy show ''[[Saturday Night Live]]'' featured a chicken [[pet store]] with the Chinese owner (as played by [[Dana Carvey]]) not wishing to sell to customers on the basis that "Chickens make lousy house pets."


== Dispersal ==
==Chickens in agriculture==
[[Image:Chickens drinking.jpg|thumb|250px|Free Range Chickens Drinking from a tire]]
In the United States, chickens were once raised primarily on family farms. Prior to about 1930, chicken was served primarily on special occasions or on Sunday, as the birds were typically more valued for their eggs than meat. Excess roosters or non-productive hens would be culled from the flock first for butchering. As cities developed and markets sprung up across the nation, live chickens from local farms could often be seen for sale in crates outside the market to be butchered and cleaned onsite by the [[butcher]].


=== Austronesia ===
With the advent of [[vertical integration]] and selective breeding of efficient meat-type birds, poultry production changed dramatically. Large farms and packing plants emerged that could grow birds by the thousands. Chickens could be sent to slaughterhouses for butchering and processing into pre-packaged commercial products to be frozen or shipped fresh to markets or wholesalers. Meat-type chickens currently grow to market weight in 6-7 weeks whereas only fifty years ago it took three times as long (reference: Havenstein, G.B., P.R. Ferket, and M.A. Qureshi, 2003a. Growth, livability, and feed conversion of 1957 versus 2001 broilers when feed representative 1957 and 2001 broiler diets. Poult. Sci. 82:1500-1508). This is due exclusively to genetic selection and nutritional advances (and not to use of growth hormones, which are illegal for use in poultry in the US and many other countries). Once a meat consumed only occasionally, the common availability and lower cost has made chicken a common and significant meat product within developed nations. Growing concerns over the [[cholesterol]] content of red meat in the 1980s and 1990s further resulted in increased consumption of chicken.


[[File:Map showing prehistoric diffusion of domestic chickens (Gallus gallus) into the Pacific via the Austronesian migrations (Thomson, Lebrasseur, & Austin, 2014).png|thumb|upright=2|Prehistoric introduction of domesticated chickens into [[Oceania]] from the [[Philippines]] via [[Neolithic]] [[Austronesian expansion]] (starting at c. 4000 [[Before present|BP]]), inferred from genetic markers on ancient and modern chicken DNA (Thomson ''et al.'', 2014)<ref name="Thomson"/>]]
Another breed of chicken, the Leghorn, was further developed to be efficient layers of eggs. Egg production and consumption changed with the development of automation and refrigeration. Large farms were devoted solely to egg production and [[packaging]]. Today, eggs are produced on large egg ranches on which environmental parameters are well controlled. Chickens are exposed to artificial light cycles to stimulate egg production year-round. In addition, it is a common practice to induce [[molt]] through careful manipulation of light and the amount of food they receive in order to further increase egg size and production.


A word for the domestic chicken (''*manuk'') is part of the reconstructed [[Proto-Austronesian language]], indicating they were [[Domesticated plants and animals of Austronesia|domesticated]] by the [[Austronesian peoples]] since ancient times. Chickens, together with dogs and pigs, were carried throughout the entire range of the prehistoric Austronesian maritime migrations to [[Island Southeast Asia]], [[Micronesia]], [[Island Melanesia]], [[Polynesia]], and [[Madagascar]], starting from at least 3000&nbsp;BC from [[Indigenous Taiwanese|Taiwan]].<ref name= Thomson>{{cite journal |last=Thomson |first=Vicki A. |others= et al. |title=Using ancient DNA to study the origins and dispersal of ancestral Polynesian chickens across the Pacific |journal=Proceedings of the National Academy of Sciences |date=April 2014 |volume=111 |issue=13 |pages=4826–4831 |doi=10.1073/pnas.1320412111 |pmid=24639505 |pmc=3977275 |bibcode=2014PNAS..111.4826T |doi-access=free }}</ref><ref name= Piper>{{cite book |first1=Philip J. |last1=Piper |editor1-first=Philip J. |editor1-last=Piper |editor2-first=Hirofumi |editor2-last=Matsumura |editor3-first=David |editor3-last=Bulbeck |title=New Perspectives in Southeast Asian and Pacific Prehistory |chapter=The Origins and Arrival of the Earliest Domestic Animals in Mainland and Island Southeast Asia: A Developing Story of Complexity |publisher=[[ANU Press]] |volume=45 |series=terra australis |year=2017 |isbn=9781760460945 |chapter-url =http://press-files.anu.edu.au/downloads/press/n2320/html/ch15.xhtml |access-date =May 5, 2023 |archive-date =November 28, 2022 |archive-url =https://web.archive.org/web/20221128075413/https://press-files.anu.edu.au/downloads/press/n2320/html/ch15.xhtml |url-status =live}}</ref><ref>{{cite book |url=https://books.google.com/books?id=FJ9ULYwX3zgC&pg=PA56 |title=The Cambridge History of the Pacific Islanders |first=Malama |last=Meleisea |date=March 25, 2004 |publisher=[[Cambridge University Press]] |page=56 |access-date=March 13, 2019 |archive-url=https://web.archive.org/web/20160913140948/https://books.google.com/books?id=FJ9ULYwX3zgC&pg=PA56 |archive-date=September 13, 2016 |url-status=live |isbn=9780521003544}}</ref><ref>{{cite book |url=https://books.google.com/books?id=tlSspaBLkhoC&pg=PA411 |title=Anthropological Genetics: Theory, Methods and Applications |first=Michael H. |last=Crawford |date=March 13, 2019 |publisher=[[Cambridge University Press]] |page=411 |access-date=March 13, 2019 |via=Google Books |archive-url=https://web.archive.org/web/20160913143140/https://books.google.com/books?id=tlSspaBLkhoC&pg=PA411 |archive-date=September 13, 2016 |url-status=live |isbn=9780521546973}}</ref> These chickens might have been introduced during [[pre-Columbian]] times to [[South America]] via [[Polynesians|Polynesian]] seafarers, but evidence for this is still putative.<ref name= Neumann>{{cite news |last=Neumann |first=Scott |title=Study: The Chicken Didn't Cross The Pacific To South America |url=https://www.npr.org/sections/thetwo-way/2014/03/18/291182073/study-the-chicken-didnt-cross-the-pacific-to-south-america |access-date=May 5, 2023 |work=The Two Way |agency=NPR |date=March 18, 2014 |archive-date=May 5, 2023 |archive-url=https://web.archive.org/web/20230505060006/https://www.npr.org/sections/thetwo-way/2014/03/18/291182073/study-the-chicken-didnt-cross-the-pacific-to-south-america |url-status=live }}</ref>
Often, people in developing countries keep chickens for their eggs and meat.


=== Americas ===
== Issues with mass production ==
[[Image:Chicken11-C.JPG|thumb|400px|Battery cages, which measure 18 by 20 inches and hold 5 to 11 hens each.]]
Many animal rights advocates object to killing chickens for food or to the "[[factory farming|factory farm conditions]]" under which they are raised. They contend that commercial chicken production often involves raising the birds in large, crowded [[rearing shed]]s that prevent the chickens from engaging in many of their natural behaviors. Contrary to popular belief, however, meat-type chickens are not raised in cages and are instead raised on the floor on litter such as rice hulls. They are slaughtered prior to sexual maturity, and thus many of the aggressive behaviors seen in adult chickens (fighting, cannibalism) are seldom seen in meat-type chickens. In 2004, 8.9 billion chickens were slaughtered in the United States[http://usda.mannlib.cornell.edu/reports/nassr/poultry/ppy-bb/].


The possibility that domestic chickens were in the Americas before Western contact is debated by researchers, but blue-egged chickens, found only in the Americas and Asia, suggest an Asian origin for early American chickens. A lack of data from Thailand, Russia, the Indian subcontinent, Southeast Asia and Sub-Saharan Africa makes it difficult to lay out a clear map of the spread of chickens in these areas; better description and genetic analysis of local breeds threatened by [[extinction]] may also help with research into this area.<ref name= CHOF/> Chicken bones from the [[Arauco Peninsula]] in [[Zona Sur|south-central Chile]] were radiocarbon dated as pre-Columbian, and DNA analysis suggested they were related to prehistoric populations in Polynesia.<ref name="Borrell 2007">{{cite journal |last1=Borrell |first1=Brendan |title=DNA reveals how the chicken crossed the sea |journal=Nature |date=June 1, 2007 |volume=447 |issue=7145 |pages=620–621 |doi=10.1038/447620b |pmid=17554271 |bibcode=2007Natur.447R.620B |s2cid=4418786 |doi-access=free }}</ref><ref name="Storey 2007">{{cite journal |last=Storey |first=A. A. |others= et al. |title=Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile |journal=Proceedings of the National Academy of Sciences |date=June 19, 2007 |volume=104 |issue=25 |pages=10335–10339 |doi=10.1073/pnas.0703993104 |pmid=17556540 |pmc=1965514 |bibcode=2007PNAS..10410335S |doi-access=free }}</ref> However, further study of the same bones cast doubt on the findings.<ref>{{cite journal |last=Gongora |first=Jaime |others= et al. |year=2008 |title=Indo-European and Asian origins for Chilean and Pacific chickens revealed by mtDNA |journal=PNAS |volume=105 |issue=30 |pages=10308–10313 |doi=10.1073/pnas.0801991105 |pmid=18663216 |pmc=2492461 |bibcode=2008PNAS..10510308G |doi-access=free }}</ref><ref name= Thomson14>{{cite journal |last=Thomson |first=Vicki A.
Although many would argue that the birds are not intelligent and thus not a high priority for humane treatment on farms, a woman once brought a chicken on ''The Tonight Show with Jay Leno'' where it played "Mary Had A Little Lamb" on a toy [[piano]] and [[bowling|bowled]] 3 strikes. Animal rights groups such as [[People for the Ethical Treatment of Animals|PETA]] see this and other "amazing" trained chickens as evidence that they are intelligent and sentient and should not be killed or eaten [http://www.peta.org/factsheet/files/FactsheetDisplay.asp?ID=99].
|others= et al. |title=Using ancient DNA to study the origins and dispersal of ancestral Polynesian chickens across the Pacific |journal=Proceedings of the National Academy of Sciences |date=April 1, 2014 |volume=111 |issue=13 |pages=4826–4831 |doi=10.1073/pnas.1320412111 |pmid=24639505 |pmc=3977275 |bibcode=2014PNAS..111.4826T |doi-access=free }}</ref>


=== Eurasia ===
Another [[animal welfare]] issue is the use of [[selective breeding]] to create heavy, large-breasted birds, which can lead to crippling leg disorders and heart failure for some of the birds. In addition, many scientists have raised concerns that companies growing one variety of bird for eggs or meat are causing them to become much more susceptible to disease. For this reason, many scientists are promoting the conservation of heritage breeds to retain genetic diversity in the species.


Chicken remains have been difficult to date, given the small and fragile bird bones; this may account for discrepancies in dates given by different sources. Archaeological evidence is supplemented by mentions in historical texts from the last few centuries BC, and by depictions in prehistoric artworks, such as across Central Asia.<ref name= Peters24>{{cite journal |last=Peters |first=Carli |others= et al. |title= Archaeological and molecular evidence for ancient chickens in Central Asia |journal= Nature Communications |volume=15 |issue=1 |date=2024-04-02 |page=2697 |issn=2041-1723 |pmid=38565545 |pmc=10987595 |doi=10.1038/s41467-024-46093-2|bibcode=2024NatCo..15.2697P }}</ref> Chickens were widespread throughout southern Central Asia by the 4th century BC.<ref name= Peters24/>
==Chicken diseases==
[[Image:Mother hen with chicks.jpg|thumb|250px|right|Hen with newly hatched chicks]]
[[Image:Day old chick black background.jpg|thumb|250px|right|Day old chick]][[Image:Chikies 17apr06.jpg|thumb|250px|Baby chicks in a box]]
*[[Aspergillosis]]
*[[Avian influenza]] (bird flu) - most well-known chicken-related disease
*[[Blackhead disease]]
*[[Botulism]]
*[[Cage Layer Fatigue]]
*[[Coccidiosis]]
*[[Common cold|Cold]]s
*[[Crop bound]]
*[[Egg bound]]
*[[Erysipelas]]
*[[Fatty Liver Hemorrhagic Syndrome]]
*[[Fowl Cholera]]
*[[Fowl pox]]
*[[Fowl Typhoid]]
*[[Gallid herpesvirus 1]] Also known as Infectious Laryngotracheitis or LT
*[[Gapeworms]]
*[[Infectious Bronchitis]]
*[[Infectious Bursal Disease]] ([[Gumboro]])
*[[Infectious Coryza]]
*[[Lymphoid Leucosis]]
*[[Marek's disease]]
*[[Moniliasis]]
*[[Mycoplasmas]]
*[[Newcastle disease]]
*[[Necrotic Enteritis]]
*[[Omphalitis]] (Mushy chick disease)
*[http://poultryone.com/articles/feedinghens.html Prolapse] (in egg layers)
*[[Psittacosis]]
*[[Pullorum]] ([[Salmonella]])
*[[Scaly leg]]
*[[Squamous cell carcinoma]]
*[[Tibial dyschondroplasia]]
*[[Toxoplasmosis]]
*[[Ulcerative Enteritis]]


Middle Eastern chicken remains go back to a little earlier than 2000&nbsp;BC in [[Syria]].<ref name="CHOF">The Cambridge History of Food, 2000, [[Cambridge University Press]], Vol. 1, pp. 496-499</ref> Phoenicians spread chickens along the Mediterranean coasts as far as Iberia. During the [[Hellenistic period]] (4th–2nd centuries BC), in the southern [[Levant]], chickens began to be widely domesticated for food.<ref name= pmid26195775>{{cite journal |last1=Perry-Gal |first1=Lee |last2=Erlich |first2=Adi |last3=Gilboa |first3=Ayelet |last4=Bar-Oz |first4=Guy |date=August 11, 2015 |title=Earliest economic exploitation of chicken outside East Asia: Evidence from the Hellenistic Southern Levant |journal=Proceedings of the National Academy of Sciences |volume=112 |issue=32 |pages=9849–9854 |bibcode=2015PNAS..112.9849P |doi=10.1073/pnas.1504236112 |pmc=4538678 |pmid=26195775 |doi-access=free}}</ref> The first pictures of chickens in Europe are found on [[Corinth, Greece|Corinthian]] [[pottery]] of the 7th century BC.<ref>{{cite book |url=https://books.google.com/books?id=NrIapgM4LwQC&pg=PA176 |title=Regional Greek Cooking |first1=Dean |last1=Karayanis |first2=Catherine |last2=Karayanis |date=March 13, 2019 |publisher=[[Hippocrene Books]] |page=176 |access-date=March 13, 2019 |via=Google Books |archive-url=https://web.archive.org/web/20160913141141/https://books.google.com/books?id=NrIapgM4LwQC&pg=PA176 |archive-date=September 13, 2016 |url-status=live |isbn=9780781811460}}</ref><ref>{{cite book |url=https://books.google.com/books?id=Xwq1lunLkuoC&pg=PA207 |title=Cooking with the Bible: Biblical Food, Feasts, and Lore |first1=Anthony F. |last1=Chiffolo |first2=Rayner W. |last2=Hesse |date=March 13, 2019 |publisher=[[Greenwood Publishing Group]] |page=207 |access-date=March 13, 2019 |via=Google Books |archive-url=https://web.archive.org/web/20160913080305/https://books.google.com/books?id=Xwq1lunLkuoC&pg=PA207 |archive-date=September 13, 2016 |url-status=live |isbn=9780313334108}}</ref>
Chickens are also susceptible to [[parasite]]s, including [[lice]], [[mite]]s, [[tick]]s, [[flea]]s, and [[Roundworm|intestinal Worm]]s.


Breeding increased under the [[Roman Empire]] and reduced in the [[Middle Ages]].<ref name= CHOF/> [[DNA sequencing|Genetic sequencing]] of chicken bones from archaeological sites in Europe revealed that in the [[High Middle Ages]] chickens became less aggressive and began to lay eggs earlier in the breeding season.<ref name= brown>{{cite journal |last1=Brown |first1=Marley |title=Fast Food |journal=Archaeology |date=Sep–Oct 2017 |volume=70 |issue=5 |page=18 |url=https://www.archaeology.org/issues/269-1709/from-the-trenches/5820-trenches-europe-chicken-domestication |access-date=July 25, 2019 |issn=0003-8113 |archive-date=July 25, 2019 |archive-url=https://web.archive.org/web/20190725160925/https://www.archaeology.org/issues/269-1709/from-the-trenches/5820-trenches-europe-chicken-domestication |url-status=live }}</ref>
[[Chickenpox]] is a disease of humans, not chickens.


==Chickens in religion==
=== Africa ===


Chickens reached Egypt via the Middle East for purposes of [[cockfighting]] about 1400&nbsp;BC and became widely bred in Egypt around 300&nbsp;BC.<ref name="CHOF"/> Three possible routes of introduction into Africa around the early first millennium AD could have been through the Egyptian [[Nile River|Nile]] Valley, the East Africa Roman-Greek or Indian trade, or from Carthage and the Berbers, across the [[Sahara Desert|Sahara]]. The earliest known remains are from [[Mali]], [[Nubia]], East Coast, and [[South Africa]] and date back to the middle of the first millennium AD.<ref name= CHOF/>
[[Image:Huehner.jpg|thumb|Chickens, [[Indonesia]]]]
In [[Indonesia]] the chicken has great significance during the [[Hinduism|Hindu]] [[cremation]] ceremony. A chicken is a channel for evil spirits which may be present during the ceremony. A chicken is tethered by the leg and kept present at the ceremony for the duration to ensure that any evil spirits present during the ceremony go into the chicken and not the family members present. The chicken is then taken home and returns to its normal life. It is not treated in any special way or slaughtered after the ceremony.


== Diseases ==
In [[ancient Greece]], the chicken was not normally used for sacrifices, perhaps because it was still considered an exotic animal. Because of its valour, cocks are found as attributes of [[Ares]], [[Heracles]] and [[Athena]]. The Greeks believed that even lions were afraid of cocks. Several of [[Aesop's Fables]] reference this belief.


{{main |Poultry disease}}
In the cult of [[Mithras]], the cock was a symbol of the divine light and a guardian against evil.{{citation needed}}


[[File:Pesse oujheas H9N2 tanfla.JPG|thumb|8 day old chick with [[avian influenza]] ]]
In the [[Bible]], [[Jesus]] prophesied the betrayal by [[Peter]]: "And he said, I tell thee, Peter, the cock shall not crow this day, before that thou shalt thrice deny that thou knowest me." ([[Gospel of Luke|Luke]] 22:43) Thus it happened (Luke 22:61), and Peter cried bitterly. This made the cock a symbol for both vigilance and betrayal.


Chickens are susceptible both to [[Parasitism|parasite]]s such as [[mite]]s, and to [[Poultry disease|diseases]] caused by [[pathogen]]s such as [[bacteria]] and [[virus]]es. The parasite ''[[Dermanyssus gallinae]]'' feeds on blood, causing irritation and reducing egg production, and acts as a vector for bacterial diseases such as [[salmonellosis]] and [[Borrelia anserina|spirochaetosis]].<ref name="Schiavone Pugliese 2022">{{Cite journal |last1=Schiavone |first1=Antonella |last2=Pugliese |first2=Nicola |last3=Otranto |first3=Domenico |last4=Samarelli |first4=Rossella |last5=Circella |first5=Elena |last6=De Virgilio |first6=Caterina |last7=Camarda |first7=Antonio |date=2022-01-20 |title=''Dermanyssus gallinae'': the long journey of the poultry red mite to become a vector |journal=Parasites & Vectors |volume=15 |issue=1 |pages=29 |doi=10.1186/s13071-021-05142-1 |pmid=35057849 |issn=1756-3305 |pmc=8772161 |doi-access=free }}</ref>
Earlier, Jesus compares himself to a mother hen, when talking about [[Jerusalem]]: "How often would I have gathered thy children together, even as a hen gathereth her chickens under her wings, and ye would not!" ([[Gospel of Matthew|Matthew]] 23:37; also Luke 13:34).
Viral diseases include [[avian influenza]].<ref>{{cite journal |last1=Barjesteh |first1=Neda |last2=O'Dowd |first2=Kelsey |last3=Vahedi |first3=Seyed Milad |title=Antiviral responses against chicken respiratory infections: Focus on avian influenza virus and infectious bronchitis virus |journal=Cytokine |date=March 2020 |volume=127 |pages=154961 |doi=10.1016/j.cyto.2019.154961 |pmid=31901597|pmc=7129915 }}</ref>


== Use by humans ==
In many Central European folk tales, the [[devil]] is believed to flee at the first crowing of a cock.


=== Farming ===
In some sects of [[Orthodox Judaism]] a chicken is slaughtered on the afternoon before [[Yom Kippur]] (Day of Atonement) in a ritual called [[kapparos]]. Although not actually a sacrifice in the biblical sense, the death of the chicken reminds the penitent sinner that his or her life is in God's hands. A woman brings a hen to be slaughtered, a man brings a rooster. The meat is donated to the poor.


{{Main|Poultry farming}}
The [[Talmud]] speaks of learning "courtesy toward one's mate" from the rooster. This might refer to the fact that, when a rooster finds something good to eat, he calls his hens to eat first.


Chickens are common and widespread domestic animals, with a total population of 23.7 billion {{As of|2018|lc=y}}.<ref>{{cite web|title=Number of chickens worldwide from 1990 to 2018.|url=https://www.statista.com/statistics/263962/number-of-chickens-worldwide-since-1990/|access-date=February 23, 2020|website=Statista|archive-date=November 27, 2020|archive-url=https://web.archive.org/web/20201127124744/https://www.statista.com/statistics/263962/number-of-chickens-worldwide-since-1990/|url-status=live}}</ref> More than 50 billion chickens are reared annually as a source of meat and eggs.<ref>{{Cite web |url=https://www.ciwf.org.uk/farm-animals/chickens/ |title=About chickens |publisher=[[Compassion in World Farming]] |access-date=April 25, 2017 |archive-url=https://web.archive.org/web/20170426063521/https://www.ciwf.org.uk/farm-animals/chickens/ |archive-date=April 26, 2017 |url-status=live }}</ref> In the United States alone, more than 8 billion chickens are slaughtered each year for meat,<ref>{{Cite web |url=https://usda.library.cornell.edu/concern/publications/pg15bd88s |title=Poultry Slaughter Annual Summary |last=Fereira |first=John |website=usda.mannlib.cornell.edu |access-date=April 25, 2017 |archive-url=https://web.archive.org/web/20170426063701/http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1497 |archive-date=April 26, 2017 |url-status=live }}</ref> and more than 300 million chickens are reared for egg production.<ref>{{Cite web |url=https://usda.library.cornell.edu/concern/publications/1v53jw96n |title=Chickens and Eggs Annual Summary |last=Fereira |first=John |website=usda.mannlib.cornell.edu |access-date=April 25, 2017 |archive-url=https://web.archive.org/web/20170426061324/http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1509 |archive-date=April 26, 2017 |url-status=live }}</ref> The vast majority of poultry is raised in [[Intensive animal farming|factory farms]]. According to the [[Worldwatch Institute]], 74% of the world's poultry meat and 68% of eggs are produced this way.<ref>{{cite web |title=Towards Happier Meals In A Globalized World |url=http://www.worldwatch.org/towards-happier-meals-globalized-world |publisher=[[Worldwatch Institute]] |access-date=May 29, 2014 |archive-url=https://web.archive.org/web/20140529153518/http://www.worldwatch.org/towards-happier-meals-globalized-world |archive-date=May 29, 2014 |url-status=dead }}</ref> An alternative to intensive poultry farming is [[free-range]] farming. Friction between these two main methods has led to long-term issues of [[ethical consumerism]]. Opponents of [[intensive farming]] argue that it harms the environment, creates human health risks and is inhumane towards [[Sentience in animals|sentient animals]].<ref>{{cite journal |last1=Ilea |first1=Ramona Cristina |title=Intensive Livestock Farming: Global Trends, Increased Environmental Concerns, and Ethical Solutions |journal=Journal of Agricultural and Environmental Ethics |date=April 2009 |volume=22 |issue=2 |pages=153–167 |doi=10.1007/s10806-008-9136-3 |bibcode=2009JAEE...22..153I |s2cid=154306257 }}</ref> Advocates of intensive farming say that their efficient systems save land and food resources owing to increased productivity, and that the animals are looked after in a controlled environment.<ref>{{cite journal |last1=Tilman |first1=David |last2=Cassman |first2=Kenneth G. |last3=Matson |first3=Pamela A. |last4=Naylor |first4=Rosamond |last5=Polasky |first5=Stephen |title=Agricultural sustainability and intensive production practices |journal=Nature |date=August 2002 |volume=418 |issue=6898 |pages=671–677 |doi=10.1038/nature01014 |pmid=12167873 |bibcode=2002Natur.418..671T |s2cid=3016610 }}</ref> Chickens farmed for meat are called [[broiler]]s. Broiler breeds typically take less than six weeks to reach slaughter size,<ref>{{cite web |url=https://www.animalsaustralia.org/factsheets/broiler_chickens.php |title=Broiler Chickens Fact Sheet |website=Animals Australia |access-date=August 29, 2010 |archive-url=https://web.archive.org/web/20100712123234/http://www.animalsaustralia.org/factsheets/broiler_chickens.php |archive-date=July 12, 2010 |url-status=live }}</ref> some weeks longer for [[free range]] and [[Organic (food)|organic]] broilers.<ref>{{cite web |title=Chickens Farmed for Meat |url=https://www.ciwf.org.uk/farm-animals/chickens/meat-chickens/ |publisher=[[Compassion in World Farming]] |access-date=2 February 2024 |archive-date=September 21, 2024 |archive-url=https://web.archive.org/web/20240921105646/https://www.ciwf.org.uk/farm-animals/chickens/meat-chickens/ |url-status=live }}</ref>
The chicken is one of the [[Zodiac]] symbols of the [[Chinese calendar]]. Also in [[Chinese religion]], a cooked chicken as a religious offering is usually limited to ancestor veneration and worship of village deities. Vegetarian deities such as [[Buddha]] are not one of the recipients of such offerings. Under some observations, an offering of chicken is present with "serious" prayer (while roasted pork is offered during a joyous celebration). In some old [[Confucian]] Chinese [[Wedding]] a chicken can be used as a substitute of that person if they are seriously ill or not available (e.g sudden death) to attend during the ceremony. They will put a red silk scarf on the chickens head and a close relative of the absent bride/groom will be holding the chicken to continue with the ceremony. However this occurrence happens rarely in modern time and usually better to avoid.


[[File:Florida chicken house.jpg|thumb|A commercial chicken house with open sides raising broiler pullets for meat]]
==History==
The first pictures of chickens in Europe are found on [[Corinth, Greece|Corinthian]] [[pottery]] of the [[7th century BC]]. The poet [[Cratinus]] (mid-[[5th century BC]], according to the later Greek author [[Athenaeus]]) calls the chicken "the [[Iran|Persia]]n alarm". In [[Aristophanes]]'s comedy ''[[The Birds (play)|The Birds]]'' ([[414 BC]]) a chicken is called "the [[Medes|Median]] bird", which points to an introduction from the East. Pictures of chickens are found on Greek [[red-figure pottery|red figure]] and [[black-figure pottery]].


Chickens farmed primarily for eggs are called layer hens. The UK alone consumes more than 34 million eggs per day.<ref>{{Cite web |url=https://www.egginfo.co.uk/egg-facts-and-figures/industry-information/data |title=UK Egg Industry Data |website=Official Egg Info |access-date=April 25, 2017 |archive-url=https://web.archive.org/web/20161230000509/https://www.egginfo.co.uk/egg-facts-and-figures/industry-information/data |archive-date=December 30, 2016 |url-status=live }}</ref> Hens of some breeds can produce over 300 eggs per year; the highest authenticated rate of egg laying is 371 eggs in 364 days.<ref>{{cite book |last1=Glenday |first1=Craig |title=Guinness World Records 2011 |date=April 26, 2011 |publisher=[[Jim Pattison Group]] |isbn=978-0440423102 |page=286}}</ref> After 12 months of laying, the commercial hen's egg-laying ability declines to the point where the flock is commercially unviable. Hens, particularly from [[battery cage]] systems, are sometimes infirm or have lost a significant amount of their feathers, and their life expectancy has been reduced from around seven years to less than two years.<ref name="Browne">{{cite news |url=https://www.theguardian.com/lifeandstyle/2002/mar/10/foodanddrink.features1 |work=The Guardian |location=London |title=Ten weeks to live |first=Anthony |last=Browne |date=March 10, 2002 |access-date=April 28, 2010 |archive-url=https://web.archive.org/web/20080516080228/http://observer.guardian.co.uk/foodmonthly/story/0,,662799,00.html |archive-date=May 16, 2008 |url-status=live }}</ref> In the UK and Europe, laying hens are then slaughtered and used in processed foods, or sold as 'soup hens'.<ref name="Browne" /> In some other countries, flocks are sometimes [[Forced molting|force moulted]] rather than being slaughtered to re-invigorate egg-laying. This involves complete withdrawal of food (and sometimes water) for 7–14 days<ref name="Patwardhan and King, (2011)">{{cite journal |last1=Patwardhan |first1=D. |last2=King |first2=A. |year=2011 |title=Review: feed withdrawal and non feed withdrawal moult |journal=World's Poultry Science Journal |volume=67 |issue=2 |pages=253–268 |doi=10.1017/s0043933911000286|s2cid=88353703 }}</ref> or sufficiently long to cause a body weight loss of 25 to 35%,<ref name="Webster, (2003)">{{cite journal |last1=Webster |first1=A.B. |year=2003 |title=Physiology and behavior of the hen during induced moult |journal=Poultry Science |volume=82 |issue=6 |pages=992–1002 |doi=10.1093/ps/82.6.992 |pmid=12817455|doi-access=free }}</ref> or up to 28 days under experimental conditions.<ref name="Molino et al., (2009)">{{cite journal |last1=Molino |first1=A.B. |last2=Garcia |first2=E.A. |last3=Berto |first3=D.A. |last4=Pelícia |first4=K. |last5=Silva |first5=A.P. |last6=Vercese |first6=F. |year=2009 |title=The Effects of Alternative Forced-Molting Methods on The Performance and Egg Quality of Commercial Layers |journal=Brazilian Journal of Poultry Science |volume=11 |issue=2 |pages=109–113 |doi=10.1590/s1516-635x2009000200006|doi-access=free |hdl=11449/14340 |hdl-access=free }}</ref> This stimulates the hen to lose her feathers but also re-invigorates egg-production. Some flocks may be force-moulted several times. In 2003, more than 75% of all flocks were moulted in the US.<ref name="Yousaf and Chaudhry, (2008)">{{cite journal |last1=Yousaf |first1=M. |last2=Chaudhry |first2=A.S. |title=History, changing scenarios and future strategies to induce moulting in laying hens |journal=World's Poultry Science Journal |date=March 1, 2008 |volume=64 |issue=1 |pages=65–75 |doi=10.1017/s0043933907001729 |s2cid=34761543 |url=http://eprint.ncl.ac.uk/file_store/production/56559/452E6892-26EF-40C6-891B-048E9FE17D2E.pdf |access-date=October 23, 2020 |archive-date=November 24, 2020 |archive-url=https://web.archive.org/web/20201124090812/https://eprint.ncl.ac.uk/file_store/production/56559/452E6892-26EF-40C6-891B-048E9FE17D2E.pdf |url-status=live }}</ref>
In ancient Greece, chickens were still rare and were a rather prestigious food for [[Symposium|symposia]]. [[Delos]] seems to have been a centre of chicken breeding.


=== As pets ===
An early domestication of chickens in [[Southeast Asia]] is probable, since the word for domestic chicken (''*manuk'') is part of the reconstructed [[Proto-Austronesian language]] (see [[Austronesian languages]]). Chickens, together with [[dog]]s and [[pig]]s, were the domestic animals of the [[Lapita]] culture, the first [[Neolithic]] culture of [[Oceania]].


Keeping chickens as pets became increasingly popular in the 2000s<ref>{{cite news |title=Some homeowners find chickens all the rage |work=[[Chicago Tribune]] |date=July 27, 2007 |last=Fly |first=Colin |url=https://pqasb.pqarchiver.com/chicagotribune/access/1310840201.html?.dids=1310840201:1310840201&FMT=ABS&FMTS=ABS:FT&type=current&date=Jul+27,+2007&author=Colin+Fly&pub=Chicago+Tribune&desc=Some+homeowners+find+chickens+all+the+rage&pqatl=google }}{{dead link|date=July 2024|bot=medic}}{{cbignore|bot=medic}}</ref> among urban and suburban residents.<ref>{{cite news |title=Cooped up in suburbia |work=[[Boston Globe]] |date=December 16, 2004 |last=Pollack-Fusi |first=Mindy |url=https://www.boston.com/yourlife/home/articles/2004/12/16/cooped_up_in_suburbia/ |access-date=June 4, 2020 |archive-date=March 4, 2016 |archive-url=https://web.archive.org/web/20160304063550/http://www.boston.com/yourlife/home/articles/2004/12/16/cooped_up_in_suburbia/ |url-status=live }}</ref> Many people obtain chickens for their egg production but often name them and treat them as any other pet like cats or dogs. Chickens provide companionship and have individual personalities. While many do not cuddle much, they will eat from one's hand, jump onto one's lap, respond to and follow their handlers, as well as show affection.<ref>{{Cite news|url=https://www.nytimes.com/2020/11/25/magazine/backyard-chickens-empathy.html |archive-url=https://web.archive.org/web/20201125101336/https://www.nytimes.com/2020/11/25/magazine/backyard-chickens-empathy.html |archive-date=November 25, 2020 |url-access=subscription |url-status=live|title = How Caring for Backyard Chickens Stretched My Emotional Muscles|newspaper = The New York Times|date = November 25, 2020|last1 = Kreilkamp|first1 = Ivan}}</ref><ref>{{Cite web|url=https://www.latimes.com/style/pets/la-hm-pets-chickens-20170827-story.html|title=Chickens will become a beloved pet — just like the family dog|last=Boone|first=Lisa|website=[[Los Angeles Times]]|date=August 27, 2017|access-date=April 3, 2019|archive-date=April 2, 2019|archive-url=https://web.archive.org/web/20190402104824/https://www.latimes.com/style/pets/la-hm-pets-chickens-20170827-story.html|url-status=live}}</ref> Chickens are social, inquisitive, intelligent<ref>{{Cite web|last=Barras|first=Colin|title=Despite what you might think, chickens are not stupid|url=https://www.bbc.com/earth/story/20170110-despite-what-you-might-think-chickens-are-not-stupid|archive-url=https://web.archive.org/web/20210605084929/https://www.bbc.com/earth/story/20170110-despite-what-you-might-think-chickens-are-not-stupid|archive-date=June 5, 2021|access-date=September 6, 2020|website=www.bbc.com|language=en}}</ref> birds, and many people find their behaviour entertaining.<ref name='UPC good homes' >{{cite web |url=https://www.upc-online.org/home.html |title=Providing a Good Home for Chickens |author=United Poultry Concerns |access-date=May 4, 2009 |archive-url=https://web.archive.org/web/20090605061816/http://www.upc-online.org/home.html |archive-date=June 5, 2009 |url-status=live }}</ref> Certain breeds, such as [[silkie]]s and many [[Bantam (poultry)|bantam]] varieties, are generally docile and are often recommended as good pets around children with disabilities.<ref>{{cite web |url=https://www.henkeeping.co.uk/henkeeping/choosing-your-chickens/ |website=Clucks and Chooks |title=Choosing Your Chickens |url-status=live |archive-url=https://web.archive.org/web/20090730222405/http://www.henkeeping.co.uk/which.html |archive-date=July 30, 2009}}</ref>
Chickens were spread by [[Polynesia]]n seafarers and reached [[Easter Island]] in the [[12th century]] AD, where they were the only domestic animal, with the possible exception of the [[Polynesian Rat]] (''Rattus exulans''). They were housed in extremely solid chicken coops built from stone. Traveling as cargo on trading boats, they reached the Asian continent via the islands of Indonesia and from there spread west to Europe and western Asia.


=== Cockfighting ===
===Chickens in ancient Rome===
The [[ancient Rome|Roman]]s used chickens for oracles, both when flying ("ex avibus") and when feeding ("auspicium ex tripudiis"). The hen ("gallina") gave a favourable omen ("auspicium ratum"), when appearing from the left (Cic.,de Div. ii.26), like the crow and the owl.


{{main|Cockfight}}
For the oracle "ex tripudiis" according to [[Cicero]] (Cic. de Div. ii.34), any bird could be used, but normally only chickens ("pulli") were consulted. The chickens were cared for by the pullarius, who opened their cage and fed them pulses or a special kind of soft cake when an augury was needed. If the chickens stayed in their cage, made noises ("occinerent"), beat their wings or flew away, the omen was bad; if they ate greedily, the omen was good.


[[File:COCK FIGHT.JPG|thumb|A [[cockfight]] in [[Tamil Nadu]], India, 2011 ]]
In [[249 BC]], the Roman general [[Publius Claudius Pulcher]] had his chickens thrown overboard when they refused to feed before the [[battle of Drepana]], saying "If they won't eat, perhaps they will drink." He promptly lost the battle against the [[Carthaginian]]s and 93 Roman ships were sunk. Back in Rome, he was tried for impiety and heavily fined.


A [[cockfight]] is a contest held in a ring called a cockpit between two cocks. Cockfighting is outlawed in many countries as involving [[cruelty to animals]].<ref>{{cite news|author=Raymond Hernandez |url=https://www.nytimes.com/1995/04/11/nyregion/blood-sport-gets-blood-fans-cockfighting-don-t-understand-its-outlaw-status.html?pagewanted=all&src=pm |title=A Blood Sport Gets in the Blood; Fans of Cockfighting Don't Understand Its Outlaw Status |work=The New York Times |location=New York City Metropolitan Area |date=1995-04-11 |access-date=2014-05-10}}</ref> The activity seems to have been practised in the [[Indus Valley civilisation]] from 2500 to 2100 BC.<ref name="Crawford 1990">{{cite book |last=Crawford |first=R. D. |title=''Poultry Breeding and Genetics'' |publisher=[[Elsevier]] |year=1990 |pages=10–11 |isbn=978-0444885579 |ol=2207173M |url=https://openlibrary.org/books/OL2207173M/Poultry_breeding_and_genetics |access-date=February 2, 2024 |archive-date=April 18, 2023 |archive-url=https://web.archive.org/web/20230418123608/https://openlibrary.org/books/OL2207173M/Poultry_breeding_and_genetics |url-status=live }}</ref> In the process of domestication, chickens were apparently kept initially for cockfighting, and only later used for food.<ref name="Lawler Adler 2012">{{cite journal |last1=Lawler |first1=Andrew |last2=Adler |first2=Jerry |title=How the Chicken Conquered the World |journal=Smithsonian Magazine |issue=June 2012 |date=June 2012 |url=http://www.smithsonianmag.com/history/how-the-chicken-conquered-the-world-87583657/ |access-date=February 2, 2024 |archive-date=October 31, 2019 |archive-url=https://web.archive.org/web/20191031040210/https://www.smithsonianmag.com/history/how-the-chicken-conquered-the-world-87583657/ |url-status=live }}</ref>
In [[161 BC]] a law was passed in Rome that forbade the consumption of fattened chickens. It was renewed a number of times, but does not seem to have been successful. Fattening chickens with bread soaked in milk was thought to give especially delicious results. The Roman gourmet [[Apicius]] offers 17 recipes for chicken, mainly boiled chicken with a sauce. All parts of the animal are used: the [[recipe]]s include the [[stomach]], [[liver]], [[testicle]]s and even the [[pygostyle]] (the fatty "tail" of the chicken where the tail feathers attach).


=== In science===
The Roman author [[Columella]] gives advice on chicken breeding in his eighth book of his treatise on [[agriculture]]. He identifies Tanagrian, Rhodic, Chalkidic and Median (commonly misidentified as Melian) breeds, which have an impressive appearance, a quarrelsome nature and were used for [[cockfighting]] by the Greeks. For farming, native (Roman) chickens are to be preferred, or a cross between native hens and Greek cocks. Dwarf chickens are nice to watch because of their size but have no other advantages.


Chickens have long been used as [[model organism]]s to study developing embryos. Large numbers of embryos can be provided commercially; fertilized eggs can easily be opened and used to observe the developing embryo. Equally important, embryologists can carry out experiments on such embryos, close the egg again and study the effects later in development. For instance, many important discoveries in [[limb development]] have been made using chicken embryos, such as the discovery of the [[apical ectodermal ridge]] and the [[zone of polarizing activity]].<ref>{{cite journal |last1=Young |first1=John J. |last2=Tabin |first2=Clifford J. |title=Saunders's framework for understanding limb development as a platform for investigating limb evolution |journal=Developmental Biology |date=September 2017 |volume=429 |issue=2 |pages=401–408 |doi=10.1016/j.ydbio.2016.11.005 |pmid=27840200 |pmc=5426996 }}</ref>
Per Columella, the ideal flock consists of 200 birds, which can be supervised by one person if someone is watching for stray animals. White chickens should be avoided as they are not very fertile and are easily caught by eagles or goshawks. One cock should be kept for five hens. In the case of Rhodian and Median cocks that are very heavy and therefore not much inclined to sex, only three hens are kept per cock. The hens of heavy fowls are not much inclined to brood; therefore their eggs are best hatched by normal hens. A hen can hatch no more than 15-23 eggs, depending on the time of year, and supervise no more than 30 hatchlings. Eggs that are long and pointed give more male, rounded eggs mainly female hatchlings.


The chicken was the first bird species to have its [[genome]] sequenced.<ref>{{cite journal |author=International Chicken Genome Sequencing Consortium |title=Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution |journal=Nature |date=December 9, 2004 |volume=432 |issue=7018 |pages=695–716 |doi=10.1038/nature03154 |pmid=15592404 |bibcode=2004Natur.432..695C |doi-access=free }}</ref> At 1.21 [[Gigabase|Gb]], the chicken genome is similarly sized compared to other birds, but smaller than nearly all mammals: the [[human genome]] is 3.2 [[Gigabase|Gb]].<ref>{{cite journal |last1=Gregory |first1=T. Ryan |title=Synergy between sequence and size in Large-scale genomics |journal=Nature Reviews Genetics |date=September 2005 |volume=6 |issue=9 |pages=699–708 |doi=10.1038/nrg1674|pmid=16151375 |s2cid=24237594 }}</ref> The final gene set contained 26,640 genes (including noncoding genes and [[pseudogene]]s), with a total of 19,119 protein-coding genes, a similar number to the human genome.<ref>{{cite journal |last1=Warren |first1=Wesley C. |last2=Hillier |first2=LaDeana W. |last3=Tomlinson |first3=Chad |last4=Minx |first4=Patrick |last5=Kremitzki |first5=Milinn |last6=Graves |first6=Tina |last7=Markovic |first7=Chris |last8=Bouk |first8=Nathan |last9=Pruitt |first9=Kim D. |last10=Thibaud-Nissen |first10=Francoise |last11=Schneider |first11=Valerie |last12=Mansour |first12=Tamer A. |display-authors=6 |title=A New Chicken Genome Assembly Provides Insight into Avian Genome Structure |journal=G3 |date=January 2017 |volume=7 |issue=1 |pages=109–117 |doi=10.1534/g3.116.035923 |pmid=27852011 |pmc=5217101 }}</ref> In 2006, scientists researching the ancestry of birds switched on a chicken [[recessive gene]], ''talpid2'', and found that the embryo jaws initiated formation of teeth, like those found in ancient bird fossils.<ref>[https://abcnews.go.com/Technology/story?id=1666805 Scientists Find Chickens Retain Ancient Ability to Grow Teeth] {{Webarchive|url=https://web.archive.org/web/20080620230515/https://abcnews.go.com/Technology/story?id=1666805 |date=June 20, 2008 }} Ammu Kannampilly, [[ABC News (United States)|ABC News]], February 27, 2006. Retrieved October 1, 2007.</ref>
Per Columella, Chicken coops should face southeast and lie adjacent to the kitchen, as smoke is beneficial for the animals. Coops should consist of three rooms and possess a hearth. Dry dust or ash should be provided for dust-baths.


=== In culture, folklore, and religion ===
According to Columella, chicken should be fed on barley groats, small chick-peas, millet and wheat bran, if they are cheap. Wheat itself should be avoided as it is harmful to the birds. Boiled ryegrass (''Lollium'' sp.) and the leaves and seeds of alfalfa (''Medicago sativa'' L.) can be used as well. Grape marc can be used, but only when the hens stop laying eggs, that is, about the middle of November; otherwise eggs are small and few. When feeding grape marc, it should be supplemented with some bran. Hens start to lay eggs after the winter solstice, in warm places around the first of January, in colder areas in the middle of February. Parboiled barley increases their fertility; this should be mixed with alfalfa leaves and seeds, or vetches or millet if alfalfa is not at hand. Free-ranging chickens should receive two cups of barley daily.


{{Anchor|Crowing|Cockadoodledoo|Cocka-doodle-doo}}
Columella advises farmers to slaughter hens that are older than three years, because they no longer produce sufficient eggs.
Capons were produced by burning out their spurs with a hot iron. The wound was treated with potter's chalk.


{{main|Cultural references to chickens}}
For the use of poultry and eggs in the kitchens of ancient Rome see [[Roman eating and drinking]].


Chickens are featured widely in [[folklore]], [[religion]], [[literature]], and popular culture. The chicken is a sacred animal in many cultures and deeply embedded in belief systems and religious practices.<ref name="smithsonianmag.com">{{cite magazine |last1=Adler |first1=Jerry |last2=Lawler |first2=Andrew |date=June 2012 |title=How the Chicken Conquered the World |url=https://www.smithsonianmag.com/history/how-the-chicken-conquered-the-world-87583657/ |magazine=Smithsonian |access-date=24 May 2012 |archive-url=https://web.archive.org/web/20121103193648/http://www.smithsonianmag.com/history-archaeology/How-the-Chicken-Conquered-the-World.html |archive-date=3 November 2012 |url-status=live}}</ref>
==A selection of chicken breeds==
Roosters are sometimes used for [[divination]], a practice called alectryomancy. This involves the sacrifice of a sacred rooster, often during a ritual [[cockfight]], used as a form of communication with the gods.<ref>{{cite book |url=https://books.google.com/books?id=vvVPAAAAMAAJ&q=Alectryomancy+cockfight&pg=PA394 |title=Encyclopædia Perthensis; Or Universal Dictionary of the Arts, Sciences, Literature, &c. Intended to Supersede the Use of Other Books of Reference |publisher=John Brown |year=1816 |edition=2nd |volume=1 |page=394 |access-date=February 2, 2024 |archive-date=September 21, 2024 |archive-url=https://web.archive.org/web/20240921105802/https://books.google.com/books?id=vvVPAAAAMAAJ&q=Alectryomancy+cockfight&pg=PA394#v=snippet&q=Alectryomancy%20cockfight&f=false |url-status=live }}</ref> In [[Gabriel García Márquez]]'s Nobel-Prize-winning 1967 novel ''[[One Hundred Years Of Solitude]]'', cockfighting is outlawed in the town of Macondo after the patriarch of the Buendia family murders his cockfighting rival and is haunted by the man's ghost.<ref>{{cite news |title=Love and Immolation in Argentina |url=https://www.washingtonpost.com/archive/entertainment/books/1981/08/16/love-and-immolation-in-argentina/9cf0bdac-cfc3-4198-8824-d89d5e059c55/ |newspaper=[[Washington Post]] |date=16 August 1981 |access-date=February 2, 2024 |archive-date=August 27, 2017 |archive-url=https://web.archive.org/web/20170827142619/https://www.washingtonpost.com/archive/entertainment/books/1981/08/16/love-and-immolation-in-argentina/9cf0bdac-cfc3-4198-8824-d89d5e059c55/ |url-status=live }}</ref> [[Chicken joke]]s have been made at least since ''[[The Knickerbocker]]'' published one in 1847.<ref>''The Knickerbocker, or The New York Monthly'', March 1847, p. 283.</ref> Chickens have been featured in art in farmyard scenes such as [[Adriaen van Utrecht]]'s 1646 ''Turkeys and Chickens'' and [[Walter Osborne]]'s 1885 ''Feeding the Chickens''.<ref>{{cite web |last1=Kellogg |first1=Diane M. |title=Chickens in Art History |url=https://www.paintingworldmag.com/post/chickens-in-art-history |publisher=Painting World Magazine |access-date=2 February 2024 |date=22 May 2020 |archive-date=February 2, 2024 |archive-url=https://web.archive.org/web/20240202161615/https://www.paintingworldmag.com/post/chickens-in-art-history |url-status=dead }}</ref> The [[nursery rhyme]] "[[Cock a doodle doo]]", its chorus line imitating the cockerel's call, was published in ''[[Mother Goose's Melody]]'' in 1765.<ref>{{cite book |last1=Opie |first1=Iona |last2=Opie |first2=Peter |title=The Oxford Dictionary of Nursery Rhymes |publisher=[[Oxford University Press]] |orig-year=1951 |edition=2nd |year=1997 |page=128}}</ref>
*[[Araucana]]
The 2000 animated [[adventure film|adventure]] [[comedy film]] ''[[Chicken Run]]'', directed by [[Peter Lord]] and [[Nick Park]], featured [[Anthropomorphism|anthropomorphic]] chickens with many chicken jokes.<ref>{{cite magazine |last=Corliss |first=Richard |date=2000-12-04 |title=Run, Chicken Run! |language=en-US |magazine=Time |url=https://content.time.com/time/world/article/0,8599,2047283,00.html |access-date=2023-03-23 |issn=0040-781X |archive-date=24 January 2023 |archive-url=https://web.archive.org/web/20230124033415/https://content.time.com/time/world/article/0,8599,2047283,00.html |url-status=live }}</ref><ref>{{Cite web|url=https://catalog.afi.com/Catalog/moviedetails/61096|title=AFI&#124;Catalog|access-date=17 August 2018|archive-date=17 August 2018|archive-url=https://web.archive.org/web/20180817060102/https://catalog.afi.com/Catalog/moviedetails/61096|url-status=live}}</ref><ref>{{Cite web |url=https://www.sfgate.com/movies/amp/Chicken-Recipe-Simply-Divine-Action-comedy-3239861.php|title='Chicken' Recipe Simply Divine / Action comedy blends great story, animation |website=SFGate |date=21 June 2000 |access-date=2 June 2021 |archive-date=2 June 2021 |archive-url=https://web.archive.org/web/20210602214504/https://www.sfgate.com/movies/amp/Chicken-Recipe-Simply-Divine-Action-comedy-3239861.php |url-status=live}}</ref>
*[[Australorp]]
*[[Barnevelder]]
*[[Brahma (chicken)]]
*[[Orpington (chicken)|Orpington]]
*[[Plymouth Rock (chicken)|Plymouth Rock]]
*[[Rhode Island Red]]
*[[Sussex (chicken)|Sussex]]
*[[Wyandotte (chicken)|Wyandotte]]


<gallery class=center mode=nolines widths=200 heights=180>
==Famous chickens==
File:Terracotta askos (flask) in the form of a rooster MET DP252108 (cropped).jpg|[[Etruscan civilization|Etruscan]] askos in the form of a rooster, 4th century B.C.
===Real chickens===
File:Rooster and hen, Dong Ho picture, paper - Vietnam National Museum of Fine Arts - Hanoi, Vietnam - DSC05287.JPG|Rooster and hen, [[Đông Hồ painting|Đông Hồ folk woodcut]], Vietnam
*[[Mike the Headless Chicken]]
File:Feeding the chickens, by Walter Frederick Osborne.jpg|''Feeding the chickens'' by [[Walter Osborne]], 1885
*[[Henrietta the four-legged chicken]]
File:Joseph Crawhall - Spanish Cock And Snail.jpg|[[Joseph Crawhall III]], ''Spanish Cock and Snail'', c. 1900
File:Chicken Mask Bali.jpg|Wooden chicken mask, [[Bali]], late 20th century
File:Yoruba Cockfight.jpg|Carved and painted wooden tribal statue of a cock fight, [[Yoruba culture|Yoruba]], West Africa, c. 2000
</gallery>


===Fictional chickens===
== Notes ==
*Alecto and Galina, in [[Clemens Brentano]]'s "The Tale of Gockel, Hinkel, and Gackeleia"
*[[Billina]] the talking hen, from [[L. Frank Baum]]'s ''[[Ozma of Oz]]''
*Burn Rooster, a [[Maverick (Mega Man)|Maverick]] with fire-elemental powers from the video game ''[[Mega Man X8]]'' (made by [[Capcom]])
*Camilla the Chicken, the object of [[Gonzo (Muppet)]]'s affections.
*[[Chanticleer]], the rooster from [[Geoffrey Chaucer]]'s ''[[The Canterbury Tales]]'' ("The Nun's Priest's Tale")
*[[Chanticleer]], the Elvis Presley-like rooster in the [[Don Bluth]] film ''[[Rock-a-Doodle]]''; presumably named for the Chaucer rooster.
*Chicken, from the ''[[Cow and Chicken]]'' cartoon series
*[[Chicken Boo]], from ''[[Animaniacs]]''
*[[Chicken Little]], the chicken that thought the sky was falling when an acorn landed on its head
*Chicken Man, from ''[[Chicken Man (radio series)]]''
*[[Cucco]]s (also ''Hylian Cuccos'') are a breed of chickens or chicken-like birds which feature prominently in latter installments of the [[Legend of Zelda series|''Legend of Zelda'' series]].
*[[Fission Chicken]], the Chicken of Wrath, grouchy superhero
*[[Foghorn Leghorn]], the rooster and ''[[Looney Tunes]]'' character
*Le coq d'or (The Golden Cockerel) opera by [[Rimsky-Korsakov]], with a magical cock that is supposed to crow to warn the king of advancing enemies
*Le galline penseuse of [[Luigi Malerba]] (Einaudi, 1980)
*Ginger, the protagonist of the movie ''[[Chicken Run]]''
*[[The Goose that Laid the Golden Egg]] was originally a chicken in some older versions
*''[[Jonathan Segal Chicken]]'', a [[1973 in literature|1973]] book written by [[Sol Weinstein]] and [[Howard Albrecht]], parodying ''[[Jonathan Livingston Seagull]]''
*[[The Little Red Hen]], who asked everyone in the barnyard to help bake bread
*The vicious [[Chicken of Bristol]], who was nearly stood up to by Brave Sir Robin, in ''[[Monty Python and the Holy Grail]]''.
*[[Little Jerry Seinfeld]], a fighting cock appearing in "[[The Little Jerry]]" (episode 145) of ''[[Seinfeld]]''
* [[Joey Tribbiani|Joey]] and [[Chandler Bing|Chandler]]'s [[The Chick and the Duck|chicken]] from ''[[Friends]]'', who eventually became a rooster, died some time later and was succeeded by Chick, Jr.
*[http://www.pinenet.com/~rooster/rooster2.html The Rooster Prince] is a [[parable]] written by [[Rabbi Nachman of Breslov]], in which a prince goes insane and believes himself to be a rooster (in some English translations of the tale, the species of bird is a [[turkey (bird)|turkey]])
*[[The San Diego Chicken]]
*[[Sweety the Chick]], an animated character with a ringtone
*[[The Subservient Chicken]], part of a [[viral marketing]] promotion
*[[Lord Chicken the Great]]; see [[Leongatha]]
*[[Ultra Mega Chicken]] is a legendary chicken raised from the dead by [[Billy Witch Doctor]] in [[Aqua Teen Hunger Force]]
*Roy, Booker and Sheldon from ''[[U.S. Acres]]''
*[[King Chicken]], from ''[[Duckman]]''
*Little John, Bubble, Bubble Junior,Pop, Araucana 1, Araucana II, Buffy Araucana, Mary and Sheepy are the chickens of a popular ABC television show set in Turramurra, Sydney, Australia called ''The chickens of Warragal Road''; the series ran from 1983 to 1985.
*The 'Yellow Chicken' that violently and restlessly fights Peter in ''[[Family Guy]]'' has become one of the most beloved character on the cult show
*''[[Robot Chicken]]'', a television series that appears on [[Adult Swim]], features a [[mad scientist]] in the opening theme bringing a [[roadkill]] chicken to life in [[cyborg]] form. The show itself is a [[stop-motion]] [[sketch comedy]], featuring sements which generally have nothing to do with chicken(s).
*Charles the Rooster in [[Walter R. Brooks]]' "[[Freddy the Pig]]" Series
*Henerietta the Hen in [[Walter R. Brooks]]' "[[Freddy the Pig]]" Series
*[[Super Chicken]], an animated television cartoon character
*[[Alan-a-Dale]], the Rooster in [[Disney]]'s [[Robin Hood (1973 film)|Robin Hood]]
*Gamecocks, chickens used by Masa Tom Lea and others in the book, [[Roots: The Saga of an American Family]], and in the tv miniseries [[Roots (TV miniseries)|Roots]]
*The Chickens in [[DreamWorks]]' [[Chicken Run]]
*The two chickens in the [[Foster Farms]] commercials
*The Rooster logo for [[Dickhouse Productions]] company for the tv show [[Jackass (TV series)|Jackass]]


{{notelist}}
===Mythical creatures with chicken-like anatomy===
#The hut of the Russian [[witch]] [[Baba Yaga]] moves on chicken feet
#The demon [[Abraxas]], often depicted on "[[Gnosis|Gnostic]] gems" has a cock's head, the upper body of a man, while his lower part is formed by a snake. He often holds a whip.
#The [[Basilisk]], a giant snake who kills with a single glance and poisons wells, was hatched by a toad from a hen's egg. The Basilisk will die if it hears a rooster crowing.
#The [[cockatrice]]


==Chicken as symbol==
== References ==
*The cock is a [[national symbol]] of [[France]] and is used as an (unofficial) national mascot, in particular for sports teams. See also: [[Gallic rooster]].
*The [[Rhodesia]] (now [[Zimbabwe]]) independent party [[ZANU]] party used a chicken as a symbol, since a majority of Rhodesian citizens (mostly native african black) were [[analphabetic]] due to lack of school funding for the poor, so they use symbol or mascot to identify their political party.
*The mascot of the English Premiership team [[Tottenham Hotspur F.C.|Tottenham Hotspur]] is a cockerel.
*The standard of [[Sir Robin]] from [[Monty Python and the Holy Grail]] is a chicken.
*The town of [[Denizli]] in [[Republic of Turkey]] is symbolized by a cock.
*[[Sydney Roosters]] Australian rugby league team
*The [[Rhode Island Red]] is the state bird of [[Rhode Island]].
*[[Pathé]] corporate logo
*The athletic teams of the [[University of South Carolina]] "The USC" (the original USC) use the [[Gamecock]] (the fighting cock) as mascot and use the "Gamecocks" as their moniker.
*[[Fighting Cock]] brand of Bourbon uses a mean rooster as their trademark.
*The State Bird of Delaware is the Blue Hen, as well being the Mascot for the University of Delaware sports teams.


{{reflist}}
==See also==
*[[Chicken hypnotism]]
*[[List of chicken breeds]]
*[[The chicken or the egg]]
*[[Why did the chicken cross the road?]]
*[[Rubber chicken]]


== External links ==
==Published Sources==
P. Smith, ''The Chicken Book'' (University of Georgia Press, 2000), passim.


{{Commons category|Chickens}}
==External links==
{{Commonscat|Chicken}}
{{Spoken Wikipedia|date=2024-02-22|Chicken Wikipedia.ogg}}
* {{Wikispecies-inline|Gallus gallus domesticus|''Gallus gallus domesticus''}}
{{Cookbook}}
{{Wikibooks|Raising Chickens}}
* [http://www.amerpoultryassn.com The American Poultry Association] "Serving the Fancy Poultry World for over 120 years" Information on chicken breeds, shows and the chicken hobby.
* [http://www.apa-abayouthprogramsite.org Youth site for the American Poultry Association] Educational learning tools for practical use at home and youth showmanship.
* "[http://poultryone.com Poultry One's Guide to Raising Poultry]" - Articles on raising chickens
*"[http://www.ruleworks.co.uk/poultry The Poultry Guide]" - A to Z and FAQ Knowledgebase / Chicken Reference Guide
* [http://poultryone.com/chickens.php Articles on Raising Chickens] - Chicken raising guide
*"[http://www.omlet.co.uk/guide/guide.php?view=Chickens&cat=About%20Chickens Omlet Chicken Guide]" - a comprehensive guide to keeping chickens by a UK company
* [http://www.omlet.co.uk/breeds/breeds.php?breed_type=Chickens Omlet Breed Guide] - good pictures of chickens
* [http://www.certifiedhumane.com Humane Farm Animal Care] - publish standards for humanely keeping chickens
* [http://www.cnn.com/2006/TECH/science/05/26/chicken.egg/ Chicken and egg debate unscrambled] - CNN article answering which came first
* [http://www.ourchickens.com HenTV at Ourchickens.com] - Live chicken webcam from an english garden, showing 24/7, with infra-red nightvision nest box cam.


[[Category:Chicken| ]]
{{Chicken}}
{{Poultry}}
[[Category:United States state birds]]
{{Taxonbar|from=Q780}}
[[Category:Domesticated birds]]
{{Authority control}}


[[ar:دجاج]]
[[Category:Chickens| ]]
[[Category:Birds described in 1758]]
[[bo:བྱ་ཏེ]]
[[Category:Bird common names]]
[[cs:Kur domácí]]
[[Category:Taxa named by Carl Linnaeus]]
[[pdc:Hinkel]]
[[Category:Articles containing video clips]]
[[de:Haushuhn]]
[[es:Pollo]]
[[Category:Junglefowls]]
[[fr:Poule]]
[[Category:Poultry]]
[[ko:]]
[[Category:Subspecies]]
[[Category:Cosmopolitan birds]]
[[io:Hano]]
[[Category:National symbols of Kenya]]
[[id:Ayam]]
[[Category:Heraldic beasts]]
[[it:Gallina]]
[[Category:Austronesian agriculture]]
[[he:תרנגול הבית]]
[[ka:ქათამი]]
[[la:Gallus]]
[[lt:Bankivinė višta]]
[[ms:ayam]]
[[nl:Kip (vogel)]]
[[ja:ニワトリ]]
[[nds:Hohn]]
[[pl:Kura domowa]]
[[pt:Galinha]]
[[ru:Куры]]
[[simple:Chicken]]
[[fi:Kana]]
[[sv:Höns]]
[[th:ไก่]]
[[zh:鸡]]

Latest revision as of 08:37, 17 December 2024

Chicken
Male (left) and female (right)
Domesticated
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Galliformes
Family: Phasianidae
Genus: Gallus
Species:
G. g. domesticus
Binomial name
Gallus gallus domesticus
Chicken distribution
Synonyms

Gallus domesticus L.

The chicken (Gallus domesticus) is a large and round short-winged bird, domesticated from the red junglefowl of Southeast Asia around 8,000 years ago. Most chickens are raised for food, providing meat and eggs; others are kept as pets[1] or for cockfighting.

Chickens are common and widespread domestic animals, with a total population of 26.5 billion as of 2023, and an annual production of more than 50 billion birds. A hen bred for laying can produce over 300 eggs per year. There are numerous cultural references to chickens in folklore, religion, and literature.

Nomenclature

Terms for chickens include:

  • Biddy: a chicken, or a newly hatched chicken[2][3]
  • Capon: a castrated or neutered male chicken[a]
  • Chick: a young chicken[4]
  • Chook /ʊk/: a chicken (Australia/New Zealand, informal)[5]
  • Cock: a fertile adult male chicken[6][7]
  • Cockerel: a young male chicken[8]
  • Hen: an adult female chicken[9]
  • Pullet: a young female chicken less than a year old.[10] In the poultry industry, a pullet is a sexually immature chicken less than 22 weeks of age.[11]
  • Rooster: a fertile adult male chicken, especially in North America. Originated in the 18th century, possibly as a euphemism to avoid the sexual connotation of the word cock.[12][13][14]
  • Yardbird: a chicken (southern United States, dialectal)[15]

Chicken can mean a chick, as in William Shakespeare's play Macbeth, where Macduff laments the death of "all my pretty chickens and their dam".[16] The usage is preserved in placenames such as the Hen and Chicken Islands.[17] In older sources, and still often in trade and scientific contexts, chickens as a species are described as common fowl or domestic fowl.[18]

Description

Comb of male
Comb of female, generally smaller

Chickens are relatively large birds, active by day. The body is round, the legs are unfeathered in most breeds, and the wings are short.[19] Wild junglefowl can fly; chickens and their flight muscles are too heavy to allow them to fly more than a short distance.[20] Size and coloration vary widely between breeds.[19] Newly-hatched chicks of both modern and heritage varieties weigh the same, about 37 g (1.3 oz). Modern varieties however grow much faster; by day 35 a Ross 708 broiler may weigh 1.8 kg (4.0 lb) as against the 1.05 kg (2.3 lb) of a heritage chicken of the same age.[21]

Adult chickens of both sexes have a fleshy crest on their heads called a comb or cockscomb, and hanging flaps of skin on either side under their beaks called wattles; combs and wattles are more prominent in males. Some breeds have a mutation that causes extra feathering under the face, giving the appearance of a beard.[22]

Chickens are omnivores.[23] In the wild, they scratch at the soil to search for seeds, insects, and animals as large as lizards, small snakes,[24] and young mice.[25] A chicken may live for 5–10 years, depending on the breed.[26] The world's oldest known chicken lived for 16 years.[27]

Chickens are gregarious, living in flocks, and incubate eggs and raise young communally. Individual chickens dominate others, establishing a pecking order; dominant individuals take priority for access to food and nest sites. The concept of dominance, involving pecking, was described in female chickens by Thorleif Schjelderup-Ebbe in 1921 as the "pecking order".[28][29] Male chickens tend to leap and use their claws in conflicts.[30] Chickens are capable of mobbing and killing a weak or inexperienced predator, such as a young fox.[31]

Crowing (with audio)

A male's crowing is a loud and sometimes shrill call, serving as a territorial signal to other males,[32] and in response to sudden disturbances within their surroundings. Hens cluck loudly after laying an egg and to call their chicks. Chickens give different warning calls to indicate that a predator is approaching from the air or on the ground.[33]

Reproduction and life-cycle

To initiate courting, some roosters may dance in a circle around or near a hen (a circle dance), often lowering the wing which is closest to the hen.[34] The dance triggers a response in the hen[34] and when she responds to his call, the rooster may mount the hen and proceed with the mating. Mating typically involves a sequence in which the male approaches the female and performs a waltzing display. If the female is unreceptive, she runs off; otherwise, she crouches, and the male mounts, treading with both feet on her back. After copulation the male does a tail-bending display.[35]

Sperm transfer occurs by cloacal contact between the male and female, in an action called the 'cloacal kiss'.[36] As with all birds, reproduction is controlled by a neuroendocrine system,[37] the Gonadotropin-Releasing Hormone-I neurons in the hypothalamus. Reproductive hormones including estrogen, progesterone, and gonadotropins (luteinizing hormone and follicle-stimulating hormone) initiate and maintain sexual maturation changes. Reproduction declines with age, thought to be due to a decline in GnRH-I-N.[38]

Newly hatched chicks

Hens often try to lay in nests that already contain eggs and sometimes move eggs from neighbouring nests into their own. A flock thus uses only a few preferred locations, rather than having a different nest for every bird.[39] Under natural conditions, most birds lay only until a clutch is complete; they then incubate all the eggs. This is called "going broody". The hen sits on the nest, fluffing up or pecking defensively if disturbed. She rarely leaves the nest until the eggs have hatched.[40]

Eggs of chickens from the high-altitude region of Tibet have special physiological adaptations that result in a higher hatching rate in low oxygen environments. When eggs are placed in a hypoxic environment, chicken embryos from these populations express much more hemoglobin than embryos from other chicken populations. This hemoglobin has a greater affinity for oxygen, binding oxygen more readily.[41]

Fertile chicken eggs hatch at the end of the incubation period, about 21 days; the chick uses its egg tooth to break out of the shell.[34] Hens remain on the nest for about two days after the first chick hatches; during this time the newly hatched chicks feed by absorbing the internal yolk sac.[42] The hen guards her chicks and broods them to keep them warm. She leads them to food and water and calls them towards food. The chicks imprint on the hen and subsequently follow her continually. She continues to care for them until they are several weeks old.[43]

Inbreeding of White Leghorn chickens tends to cause inbreeding depression expressed as reduced egg number and delayed sexual maturity.[44] Strongly inbred Langshan chickens display obvious inbreeding depression in reproduction, particularly for traits such as age when the first egg is laid and egg number.[45]

Origin

Phylogeny

Red junglefowl, the wild ancestor of the chicken

Water or ground-dwelling fowl similar to modern partridges, in the Galliformes, the order of bird that chickens belong to, survived the Cretaceous–Paleogene extinction event that killed all tree-dwelling birds and their dinosaur relatives.[46] Chickens are descended primarily from the red junglefowl (Gallus gallus) and are scientifically classified as the same species.[47] Domesticated chickens freely interbreed with populations of red junglefowl.[47] The domestic chicken has subsequently hybridised with grey junglefowl, Sri Lankan junglefowl and green junglefowl;[48] a gene for yellow skin, for instance, was incorporated into domestic birds from the grey junglefowl (G. sonneratii).[49] It is estimated that chickens share between 71 and 79% of their genome with red junglefowl.[48]

Domestication

Chicken domestication and dispersal;[48] possibility of early arrival in Americas[50][51]

According to one early study, a single domestication event of the red junglefowl in present-day Thailand gave rise to the modern chicken with minor transitions separating the modern breeds.[52] The red junglefowl is well adapted to take advantage of the vast quantities of seed produced during the end of the multi-decade bamboo seeding cycle, to boost its own reproduction.[53] In domesticating the chicken, humans took advantage of the red junglefowl's ability to reproduce prolifically when exposed to a surge in its food supply.[54]

Exactly when and where the chicken was domesticated remains controversial. Genomic studies estimate that the chicken was domesticated 8,000 years ago[48] in Southeast Asia and spread to China and India 2,000 to 3,000 years later. Archaeological evidence supports domestic chickens in Southeast Asia well before 6000 BC, China by 6000 BC and India by 2000 BC.[48][55][56] A landmark 2020 Nature study that fully sequenced 863 chickens across the world suggests that all domestic chickens originate from a single domestication event of red junglefowl whose present-day distribution is predominantly in southwestern China, northern Thailand and Myanmar. These domesticated chickens spread across Southeast and South Asia where they interbred with local wild species of junglefowl, forming genetically and geographically distinct groups. Analysis of the most popular commercial breed shows that the White Leghorn breed possesses a mosaic of divergent ancestries inherited from subspecies of red junglefowl.[57][58][59]

Dispersal

Austronesia

Prehistoric introduction of domesticated chickens into Oceania from the Philippines via Neolithic Austronesian expansion (starting at c. 4000 BP), inferred from genetic markers on ancient and modern chicken DNA (Thomson et al., 2014)[60]

A word for the domestic chicken (*manuk) is part of the reconstructed Proto-Austronesian language, indicating they were domesticated by the Austronesian peoples since ancient times. Chickens, together with dogs and pigs, were carried throughout the entire range of the prehistoric Austronesian maritime migrations to Island Southeast Asia, Micronesia, Island Melanesia, Polynesia, and Madagascar, starting from at least 3000 BC from Taiwan.[60][61][62][63] These chickens might have been introduced during pre-Columbian times to South America via Polynesian seafarers, but evidence for this is still putative.[64]

Americas

The possibility that domestic chickens were in the Americas before Western contact is debated by researchers, but blue-egged chickens, found only in the Americas and Asia, suggest an Asian origin for early American chickens. A lack of data from Thailand, Russia, the Indian subcontinent, Southeast Asia and Sub-Saharan Africa makes it difficult to lay out a clear map of the spread of chickens in these areas; better description and genetic analysis of local breeds threatened by extinction may also help with research into this area.[65] Chicken bones from the Arauco Peninsula in south-central Chile were radiocarbon dated as pre-Columbian, and DNA analysis suggested they were related to prehistoric populations in Polynesia.[50][51] However, further study of the same bones cast doubt on the findings.[66][67]

Eurasia

Chicken remains have been difficult to date, given the small and fragile bird bones; this may account for discrepancies in dates given by different sources. Archaeological evidence is supplemented by mentions in historical texts from the last few centuries BC, and by depictions in prehistoric artworks, such as across Central Asia.[68] Chickens were widespread throughout southern Central Asia by the 4th century BC.[68]

Middle Eastern chicken remains go back to a little earlier than 2000 BC in Syria.[65] Phoenicians spread chickens along the Mediterranean coasts as far as Iberia. During the Hellenistic period (4th–2nd centuries BC), in the southern Levant, chickens began to be widely domesticated for food.[69] The first pictures of chickens in Europe are found on Corinthian pottery of the 7th century BC.[70][71]

Breeding increased under the Roman Empire and reduced in the Middle Ages.[65] Genetic sequencing of chicken bones from archaeological sites in Europe revealed that in the High Middle Ages chickens became less aggressive and began to lay eggs earlier in the breeding season.[72]

Africa

Chickens reached Egypt via the Middle East for purposes of cockfighting about 1400 BC and became widely bred in Egypt around 300 BC.[65] Three possible routes of introduction into Africa around the early first millennium AD could have been through the Egyptian Nile Valley, the East Africa Roman-Greek or Indian trade, or from Carthage and the Berbers, across the Sahara. The earliest known remains are from Mali, Nubia, East Coast, and South Africa and date back to the middle of the first millennium AD.[65]

Diseases

8 day old chick with avian influenza

Chickens are susceptible both to parasites such as mites, and to diseases caused by pathogens such as bacteria and viruses. The parasite Dermanyssus gallinae feeds on blood, causing irritation and reducing egg production, and acts as a vector for bacterial diseases such as salmonellosis and spirochaetosis.[73] Viral diseases include avian influenza.[74]

Use by humans

Farming

Chickens are common and widespread domestic animals, with a total population of 23.7 billion as of 2018.[75] More than 50 billion chickens are reared annually as a source of meat and eggs.[76] In the United States alone, more than 8 billion chickens are slaughtered each year for meat,[77] and more than 300 million chickens are reared for egg production.[78] The vast majority of poultry is raised in factory farms. According to the Worldwatch Institute, 74% of the world's poultry meat and 68% of eggs are produced this way.[79] An alternative to intensive poultry farming is free-range farming. Friction between these two main methods has led to long-term issues of ethical consumerism. Opponents of intensive farming argue that it harms the environment, creates human health risks and is inhumane towards sentient animals.[80] Advocates of intensive farming say that their efficient systems save land and food resources owing to increased productivity, and that the animals are looked after in a controlled environment.[81] Chickens farmed for meat are called broilers. Broiler breeds typically take less than six weeks to reach slaughter size,[82] some weeks longer for free range and organic broilers.[83]

A commercial chicken house with open sides raising broiler pullets for meat

Chickens farmed primarily for eggs are called layer hens. The UK alone consumes more than 34 million eggs per day.[84] Hens of some breeds can produce over 300 eggs per year; the highest authenticated rate of egg laying is 371 eggs in 364 days.[85] After 12 months of laying, the commercial hen's egg-laying ability declines to the point where the flock is commercially unviable. Hens, particularly from battery cage systems, are sometimes infirm or have lost a significant amount of their feathers, and their life expectancy has been reduced from around seven years to less than two years.[86] In the UK and Europe, laying hens are then slaughtered and used in processed foods, or sold as 'soup hens'.[86] In some other countries, flocks are sometimes force moulted rather than being slaughtered to re-invigorate egg-laying. This involves complete withdrawal of food (and sometimes water) for 7–14 days[87] or sufficiently long to cause a body weight loss of 25 to 35%,[88] or up to 28 days under experimental conditions.[89] This stimulates the hen to lose her feathers but also re-invigorates egg-production. Some flocks may be force-moulted several times. In 2003, more than 75% of all flocks were moulted in the US.[90]

As pets

Keeping chickens as pets became increasingly popular in the 2000s[91] among urban and suburban residents.[92] Many people obtain chickens for their egg production but often name them and treat them as any other pet like cats or dogs. Chickens provide companionship and have individual personalities. While many do not cuddle much, they will eat from one's hand, jump onto one's lap, respond to and follow their handlers, as well as show affection.[93][94] Chickens are social, inquisitive, intelligent[95] birds, and many people find their behaviour entertaining.[96] Certain breeds, such as silkies and many bantam varieties, are generally docile and are often recommended as good pets around children with disabilities.[97]

Cockfighting

A cockfight in Tamil Nadu, India, 2011

A cockfight is a contest held in a ring called a cockpit between two cocks. Cockfighting is outlawed in many countries as involving cruelty to animals.[98] The activity seems to have been practised in the Indus Valley civilisation from 2500 to 2100 BC.[99] In the process of domestication, chickens were apparently kept initially for cockfighting, and only later used for food.[100]

In science

Chickens have long been used as model organisms to study developing embryos. Large numbers of embryos can be provided commercially; fertilized eggs can easily be opened and used to observe the developing embryo. Equally important, embryologists can carry out experiments on such embryos, close the egg again and study the effects later in development. For instance, many important discoveries in limb development have been made using chicken embryos, such as the discovery of the apical ectodermal ridge and the zone of polarizing activity.[101]

The chicken was the first bird species to have its genome sequenced.[102] At 1.21 Gb, the chicken genome is similarly sized compared to other birds, but smaller than nearly all mammals: the human genome is 3.2 Gb.[103] The final gene set contained 26,640 genes (including noncoding genes and pseudogenes), with a total of 19,119 protein-coding genes, a similar number to the human genome.[104] In 2006, scientists researching the ancestry of birds switched on a chicken recessive gene, talpid2, and found that the embryo jaws initiated formation of teeth, like those found in ancient bird fossils.[105]

In culture, folklore, and religion

Chickens are featured widely in folklore, religion, literature, and popular culture. The chicken is a sacred animal in many cultures and deeply embedded in belief systems and religious practices.[106] Roosters are sometimes used for divination, a practice called alectryomancy. This involves the sacrifice of a sacred rooster, often during a ritual cockfight, used as a form of communication with the gods.[107] In Gabriel García Márquez's Nobel-Prize-winning 1967 novel One Hundred Years Of Solitude, cockfighting is outlawed in the town of Macondo after the patriarch of the Buendia family murders his cockfighting rival and is haunted by the man's ghost.[108] Chicken jokes have been made at least since The Knickerbocker published one in 1847.[109] Chickens have been featured in art in farmyard scenes such as Adriaen van Utrecht's 1646 Turkeys and Chickens and Walter Osborne's 1885 Feeding the Chickens.[110] The nursery rhyme "Cock a doodle doo", its chorus line imitating the cockerel's call, was published in Mother Goose's Melody in 1765.[111] The 2000 animated adventure comedy film Chicken Run, directed by Peter Lord and Nick Park, featured anthropomorphic chickens with many chicken jokes.[112][113][114]

Notes

  1. ^ The surgical and chemical castration of chickens is now illegal in some parts of the world.

References

  1. ^ Joshua (July 27, 2020). "Chickens and Roosters…As Pets?". IAABC Foundation Journal. Retrieved December 5, 2024.
  2. ^ "Definition of biddy". Dictionary.com. Archived from the original on May 7, 2021. Retrieved May 7, 2021.
  3. ^ "Biddy definition and meaning". Collins English Dictionary. Archived from the original on May 7, 2021. Retrieved May 7, 2021.
  4. ^ "Chick". Cambridge Dictionary. Archived from the original on September 7, 2015.
  5. ^ "Chook". Cambridge Dictionary. Archived from the original on September 7, 2015. Retrieved March 4, 2021.
  6. ^ "Cock". Cambridge Dictionary. Archived from the original on September 7, 2015. Retrieved March 4, 2021.
  7. ^ "Hen". Cambridge Dictionary. Archived from the original on September 7, 2015. Retrieved March 4, 2021.
  8. ^ Cockerel. Dictionary Reference. Archived from the original on March 7, 2016. Retrieved August 29, 2010.
  9. ^ "Hen noun". Merriam-Webster. Retrieved February 2, 2024.
  10. ^ Pullet. Dictionary Reference. Archived from the original on November 9, 2010. Retrieved August 29, 2010.
  11. ^ "Overview of the Poultry Industry" (PDF). Missouri Department of Elementary and Secondary Education. p. 8. Archived (PDF) from the original on October 23, 2020.
  12. ^ "Definition of Rooster". Merriam-Webster. Archived from the original on April 22, 2021. Retrieved March 6, 2021.
  13. ^ Hugh Rawson Archived July 1, 2017, at the Wayback Machine "Why Do We Say...? Rooster", American Heritage, August–September 2006.
  14. ^ Online Etymology Dictionary Archived November 11, 2020, at the Wayback Machine Entry for rooster (n.), May 2019
  15. ^ Berhardt, Clyde E. B. (1986). I Remember: Eighty Years of Black Entertainment, Big Bands. University of Pennsylvania Press. p. 153. ISBN 978-0-8122-8018-0. OCLC 12805260.
  16. ^ Shakespeare, William, Macbeth, Act 4 Scene 3, lines 217–229.
  17. ^ "Chicken". Merriam Webster Dictionary. Archived from the original on August 21, 2008. Retrieved March 4, 2021.
  18. ^ Stevens, Lewis (1991). Genetics and evolution of the domestic fowl. Cambridge University Press. pp. 11 and throughout. ISBN 978-0-521-40317-7.
  19. ^ a b "Chicken". Smithsonian's National Zoo & Conservation Biology Institute. Archived from the original on February 2, 2024. Retrieved February 2, 2024.
  20. ^ Geggel, Laura (December 8, 2016). "Forget About the Road. Why Are Chickens So Bad at Flying?". Live Science. Archived from the original on April 4, 2024. Retrieved February 3, 2024.
  21. ^ Schmidt, C.J.; Persia, M.E.; Feierstein, E.; Kingham, B.; Saylor, W.W. (2009). "Comparison of a modern broiler line and a heritage line unselected since the 1950s". Poultry Science. 88 (12): 2610–2619. doi:10.3382/ps.2009-00055.
  22. ^ Guo, Ying; Gu, Xiaorong; Sheng, Zheya; Wang, Yanqiang; Luo, Chenglong; et al. (June 2, 2016). "A Complex Structural Variation on Chromosome 27 Leads to the Ectopic Expression of HOXB8 and the Muffs and Beard Phenotype in Chickens". PLOS Genetics. 12 (6): e1006071. doi:10.1371/journal.pgen.1006071. PMC 4890787. PMID 27253709.
  23. ^ "Info on Chicken Care". Ideas-4-pets.co.uk. 2003. Archived from the original on June 25, 2015. Retrieved August 13, 2008.
  24. ^ D Lines (July 27, 2013). "Chicken Kills Rattlesnake". YouTube. Archived from the original on December 11, 2021. Retrieved March 13, 2019.
  25. ^ Gerard P.Worrell AKA "Farmer Jerry". "Frequently asked questions about chickens & eggs". Gworrell.freeyellow.com. Archived from the original on September 16, 2008. Retrieved August 13, 2008.
  26. ^ "The Poultry Guide – A to Z and FAQs". Ruleworks.co.uk. Archived from the original on November 28, 2010. Retrieved August 29, 2010.
  27. ^ Smith, Jamon (August 6, 2006). "World's oldest chicken starred in magic shows, was on 'Tonight Show'". Tuscaloosa News. Alabama, USA. Archived from the original on February 20, 2019. Retrieved May 18, 2020.
  28. ^ Perrin, P. G. (1955). "'Pecking order' 1927–54". American Speech. 30 (4): 265–268. doi:10.2307/453561. ISSN 0003-1283. JSTOR 453561.
  29. ^ Schjelderup-Ebbe, T. (1975). "Contributions to the social psychology of the domestic chicken [Schleidt M., Schleidt, W. M., translators]". In Schein, M. W. (ed.). Social Hierarchy and Dominance. Benchmark Papers in Animal Behavior. Vol. 3. Stroudsburg, Pennsylvania: Dowden, Hutchinson and Ross. pp. 35–49. (Reprinted from Zeitschrift für Psychologie, 1922, 88:225–252.)
  30. ^ Rajecki, D. W. (1988). "Formation of leap orders in pairs of male domestic chickens". Aggressive Behavior. 14 (6): 425–436. doi:10.1002/1098-2337(1988)14:6<425::AID-AB2480140604>3.0.CO;2-#. S2CID 141664966.
  31. ^ AFP (March 12, 2019). "Chickens 'teamed up to kill fox' at Brittany farming school". Theguardian.com. Archived from the original on March 13, 2019. Retrieved March 13, 2019.
  32. ^ "Top cock: Roosters crow in pecking order". Phys.org. Archived from the original on January 15, 2018. Retrieved January 14, 2018.
  33. ^ Evans, Christopher S.; Evans, Linda; Marler, Peter (July 1993). "On the meaning of alarm calls: functional reference in an avian vocal system". Animal Behaviour. 46 (1): 23–38. doi:10.1006/anbe.1993.1158. S2CID 53165305.
  34. ^ a b c Grandin, Temple; Johnson, Catherine (2005). Animals in Translation. New York City: Scribner's. pp. 69–71. ISBN 978-0-7432-4769-6.
  35. ^ Cheng, Kimberly M.; Burns, Jeffrey T. (August 1988). "Dominance Relationship and Mating Behavior of Domestic Cocks: A Model to Study Mate-Guarding and Sperm Competition in Birds". The Condor. 90 (3): 697–704. doi:10.2307/1368360. JSTOR 1368360.
  36. ^ Briskie, J. V.; R. Montgomerie (1997). "Sexual Selection and the Intromittent Organ of Birds". Journal of Avian Biology. 28 (1): 73–86. doi:10.2307/3677097. JSTOR 3677097.
  37. ^ Dufour, Sylvie; Quérat, Bruno; Tostivint, Hervé; Pasqualini, Catherine; Vaudry, Hubert; Rousseau, Karine (April 2020). "Origin and Evolution of the Neuroendocrine Control of Reproduction in Vertebrates, With Special Focus on Genome and Gene Duplications". Physiological Reviews. 100 (2): 869–943. doi:10.1152/physrev.00009.2019. ISSN 0031-9333. PMID 31625459.
  38. ^ Bain, M. M.; Nys, Y.; Dunn, I.C. (May 3, 2016). "Increasing persistency in lay and stabilising egg quality in longer laying cycles. What are the challenges?". British Poultry Science. 57 (3). Taylor & Francis: 330–338. doi:10.1080/00071668.2016.1161727. PMC 4940894. PMID 26982003. S2CID 17842329.
  39. ^ Sherwin, C.M.; Nicol, C.J. (1993). "Factors influencing floor-laying by hens in modified cages". Applied Animal Behaviour Science. 36 (2–3): 211–222. doi:10.1016/0168-1591(93)90011-d.
  40. ^ "Why Do Chickens Puff up Their Feathers? I 4 Reasons Explained". August 8, 2020. Archived from the original on June 18, 2021. Retrieved June 16, 2021.
  41. ^ Zhang, H.; Wang, X.T.; Chamba, Y.; Ling, Y.; Wu, C.X. (October 2008). "Influences of Hypoxia on Hatching Performance in Chickens with Different Genetic Adaptation to High Altitude". Poultry Science. 87 (10): 2112–2116. doi:10.3382/ps.2008-00122. PMID 18809874.
  42. ^ Ali, A.; Cheng, K.M. (1985). "Early egg production in genetically blind (rc/rc) chickens in comparison with sighted (Rc+/rc) controls". Poultry Science. 64 (5): 789–794. doi:10.3382/ps.0640789. PMID 4001066.
  43. ^ Edgar, Joanne; Held, Suzanne; Jones, Charlotte; Troisi, Camille (January 5, 2016). "Influences of Maternal Care on Chicken Welfare". Animals. 6 (1): 2. doi:10.3390/ani6010002. PMC 4730119. PMID 26742081.
  44. ^ Sewalem, A.; Johansson, K.; Wilhelmson, M.; Lillpers, K. (1999). "Inbreeding and inbreeding depression on reproduction and production traits of White Leghorn lines selected for egg production traits". British Poultry Science. 40 (2): 203–208. doi:10.1080/00071669987601. PMID 10465386.
  45. ^ Xue, Qian; Li, Guohui; Cao, Yuxia; Yin, Jianmei; Zhu, Yunfen; Zhang, Huiyong; Zhou, Chenghao; Shen, Haiyu; Dou, Xinhong; Su, Yijun; Wang, Kehua; Zou, Jianmin; Han, Wei (June 1, 2021). "Identification of genes involved in inbreeding depression of reproduction in Langshan chickens". Animal Bioscience. 34 (6): 975–984. doi:10.5713/ajas.20.0248. ISSN 2765-0189. PMC 8100482. PMID 33152217.
  46. ^ Pennisi, Elizabeth (May 24, 2018). "Quaillike creatures were the only birds to survive the dinosaur-killing asteroid impact". Science. doi:10.1126/science.aau2802.
  47. ^ a b Wong, G. K.; Liu, B.; Wang, J.; Zhang, Y.; Yang, X.; Zhang, Z.; et al. (December 9, 2004). "A genetic variation map for chicken with 2.8 million single nucleotide polymorphisms". Nature. 432 (7018): 717–722. Bibcode:2004Natur.432..717B. doi:10.1038/nature03156. PMC 2263125. PMID 15592405.
  48. ^ a b c d e Lawal, Raman Akinyanju; Martin, Simon H.; Vanmechelen, Koen; Vereijken, Addie; Silva, Pradeepa; Al-Atiyat, Raed Mahmoud; et al. (December 2020). "The wild species genome ancestry of domestic chickens". BMC Biology. 18 (1): 13. doi:10.1186/s12915-020-0738-1. PMC 7014787. PMID 32050971.
  49. ^ Eriksson, Jonas; Larson, Greger; Gunnarsson, Ulrika; Bed'hom, Bertrand; Tixier-Boichard, Michele; Strömstedt, Lina; et al. (February 29, 2008). "Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken". PLOS Genetics. 4 (2): e1000010. doi:10.1371/journal.pgen.1000010. PMC 2265484. PMID 18454198.
  50. ^ a b Borrell, Brendan (June 1, 2007). "DNA reveals how the chicken crossed the sea". Nature. 447 (7145): 620–621. Bibcode:2007Natur.447R.620B. doi:10.1038/447620b. PMID 17554271. S2CID 4418786.
  51. ^ a b Storey, A. A. (June 19, 2007). "Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile". Proceedings of the National Academy of Sciences. 104 (25). et al.: 10335–10339. Bibcode:2007PNAS..10410335S. doi:10.1073/pnas.0703993104. PMC 1965514. PMID 17556540.
  52. ^ Fumihito, A.; Miyake, T.; Sumi, S.; Takada, M.; Ohno, S.; Kondo, N. (December 20, 1994), "One subspecies of the red junglefowl (Gallus gallus gallus) suffices as the matriarchic ancestor of all domestic breeds", PNAS, 91 (26): 12505–12509, Bibcode:1994PNAS...9112505F, doi:10.1073/pnas.91.26.12505, PMC 45467, PMID 7809067
  53. ^ King, Rick (February 24, 2009), "Rat Attack", Nova and National Geographic Television, archived from the original on August 23, 2017, retrieved August 25, 2017
  54. ^ King, Rick (February 1, 2009), "Plant vs. Predator", NOVA, archived from the original on August 21, 2017, retrieved August 25, 2017
  55. ^ West, B.; Zhou, B.X. (1988). "Did chickens go north? New evidence for domestication". J. Archaeol. Sci. 14 (5): 515–533. Bibcode:1988JArSc..15..515W. doi:10.1016/0305-4403(88)90080-5.
  56. ^ Al-Nasser, A.; Al-Khalaifa, H.; Al-Saffar, A.; Khalil, F.; Albahouh, M.; Ragheb, G.; Al-Haddad, A.; Mashaly, M. (June 1, 2007). "Overview of chicken taxonomy and domestication". World's Poultry Science Journal. 63 (2): 285–300. doi:10.1017/S004393390700147X. S2CID 86734013.
  57. ^ Wang, Ming-Shan; Thakur, Mukesh; Peng, Min-Sheng; Jiang, Yu; Frantz, Laurent Alain François; Li, Ming; et al. (2020). "863 genomes reveal the origin and domestication of chicken". Cell Research. 30 (8): 693–701. doi:10.1038/s41422-020-0349-y. PMC 7395088. PMID 32581344. S2CID 220050312.
  58. ^ Liu, Yi-Ping; Wu, Gui-Sheng; Yao, Yong-Gang; Miao, Yong-Wang; Luikart, Gordon; Baig, Mumtaz; et al. (January 2006). "Multiple maternal origins of chickens: Out of the Asian jungles". Molecular Phylogenetics and Evolution. 38 (1): 12–19. Bibcode:2006MolPE..38...12L. doi:10.1016/j.ympev.2005.09.014. PMID 16275023.
  59. ^ Zeder, Melinda A.; Emshwiller, Eve; Smith, Bruce D.; Bradley, Daniel G. (March 2006). "Documenting domestication: the intersection of genetics and archaeology". Trends in Genetics. 22 (3): 139–155. doi:10.1016/j.tig.2006.01.007. PMID 16458995.
  60. ^ a b Thomson, Vicki A. (April 2014). "Using ancient DNA to study the origins and dispersal of ancestral Polynesian chickens across the Pacific". Proceedings of the National Academy of Sciences. 111 (13). et al.: 4826–4831. Bibcode:2014PNAS..111.4826T. doi:10.1073/pnas.1320412111. PMC 3977275. PMID 24639505.
  61. ^ Piper, Philip J. (2017). "The Origins and Arrival of the Earliest Domestic Animals in Mainland and Island Southeast Asia: A Developing Story of Complexity". In Piper, Philip J.; Matsumura, Hirofumi; Bulbeck, David (eds.). New Perspectives in Southeast Asian and Pacific Prehistory. terra australis. Vol. 45. ANU Press. ISBN 9781760460945. Archived from the original on November 28, 2022. Retrieved May 5, 2023.
  62. ^ Meleisea, Malama (March 25, 2004). The Cambridge History of the Pacific Islanders. Cambridge University Press. p. 56. ISBN 9780521003544. Archived from the original on September 13, 2016. Retrieved March 13, 2019.
  63. ^ Crawford, Michael H. (March 13, 2019). Anthropological Genetics: Theory, Methods and Applications. Cambridge University Press. p. 411. ISBN 9780521546973. Archived from the original on September 13, 2016. Retrieved March 13, 2019 – via Google Books.
  64. ^ Neumann, Scott (March 18, 2014). "Study: The Chicken Didn't Cross The Pacific To South America". The Two Way. NPR. Archived from the original on May 5, 2023. Retrieved May 5, 2023.
  65. ^ a b c d e The Cambridge History of Food, 2000, Cambridge University Press, Vol. 1, pp. 496-499
  66. ^ Gongora, Jaime (2008). "Indo-European and Asian origins for Chilean and Pacific chickens revealed by mtDNA". PNAS. 105 (30). et al.: 10308–10313. Bibcode:2008PNAS..10510308G. doi:10.1073/pnas.0801991105. PMC 2492461. PMID 18663216.
  67. ^ Thomson, Vicki A. (April 1, 2014). "Using ancient DNA to study the origins and dispersal of ancestral Polynesian chickens across the Pacific". Proceedings of the National Academy of Sciences. 111 (13). et al.: 4826–4831. Bibcode:2014PNAS..111.4826T. doi:10.1073/pnas.1320412111. PMC 3977275. PMID 24639505.
  68. ^ a b Peters, Carli (April 2, 2024). "Archaeological and molecular evidence for ancient chickens in Central Asia". Nature Communications. 15 (1). et al.: 2697. Bibcode:2024NatCo..15.2697P. doi:10.1038/s41467-024-46093-2. ISSN 2041-1723. PMC 10987595. PMID 38565545.
  69. ^ Perry-Gal, Lee; Erlich, Adi; Gilboa, Ayelet; Bar-Oz, Guy (August 11, 2015). "Earliest economic exploitation of chicken outside East Asia: Evidence from the Hellenistic Southern Levant". Proceedings of the National Academy of Sciences. 112 (32): 9849–9854. Bibcode:2015PNAS..112.9849P. doi:10.1073/pnas.1504236112. PMC 4538678. PMID 26195775.
  70. ^ Karayanis, Dean; Karayanis, Catherine (March 13, 2019). Regional Greek Cooking. Hippocrene Books. p. 176. ISBN 9780781811460. Archived from the original on September 13, 2016. Retrieved March 13, 2019 – via Google Books.
  71. ^ Chiffolo, Anthony F.; Hesse, Rayner W. (March 13, 2019). Cooking with the Bible: Biblical Food, Feasts, and Lore. Greenwood Publishing Group. p. 207. ISBN 9780313334108. Archived from the original on September 13, 2016. Retrieved March 13, 2019 – via Google Books.
  72. ^ Brown, Marley (September–October 2017). "Fast Food". Archaeology. 70 (5): 18. ISSN 0003-8113. Archived from the original on July 25, 2019. Retrieved July 25, 2019.
  73. ^ Schiavone, Antonella; Pugliese, Nicola; Otranto, Domenico; Samarelli, Rossella; Circella, Elena; De Virgilio, Caterina; Camarda, Antonio (January 20, 2022). "Dermanyssus gallinae: the long journey of the poultry red mite to become a vector". Parasites & Vectors. 15 (1): 29. doi:10.1186/s13071-021-05142-1. ISSN 1756-3305. PMC 8772161. PMID 35057849.
  74. ^ Barjesteh, Neda; O'Dowd, Kelsey; Vahedi, Seyed Milad (March 2020). "Antiviral responses against chicken respiratory infections: Focus on avian influenza virus and infectious bronchitis virus". Cytokine. 127: 154961. doi:10.1016/j.cyto.2019.154961. PMC 7129915. PMID 31901597.
  75. ^ "Number of chickens worldwide from 1990 to 2018". Statista. Archived from the original on November 27, 2020. Retrieved February 23, 2020.
  76. ^ "About chickens". Compassion in World Farming. Archived from the original on April 26, 2017. Retrieved April 25, 2017.
  77. ^ Fereira, John. "Poultry Slaughter Annual Summary". usda.mannlib.cornell.edu. Archived from the original on April 26, 2017. Retrieved April 25, 2017.
  78. ^ Fereira, John. "Chickens and Eggs Annual Summary". usda.mannlib.cornell.edu. Archived from the original on April 26, 2017. Retrieved April 25, 2017.
  79. ^ "Towards Happier Meals In A Globalized World". Worldwatch Institute. Archived from the original on May 29, 2014. Retrieved May 29, 2014.
  80. ^ Ilea, Ramona Cristina (April 2009). "Intensive Livestock Farming: Global Trends, Increased Environmental Concerns, and Ethical Solutions". Journal of Agricultural and Environmental Ethics. 22 (2): 153–167. Bibcode:2009JAEE...22..153I. doi:10.1007/s10806-008-9136-3. S2CID 154306257.
  81. ^ Tilman, David; Cassman, Kenneth G.; Matson, Pamela A.; Naylor, Rosamond; Polasky, Stephen (August 2002). "Agricultural sustainability and intensive production practices". Nature. 418 (6898): 671–677. Bibcode:2002Natur.418..671T. doi:10.1038/nature01014. PMID 12167873. S2CID 3016610.
  82. ^ "Broiler Chickens Fact Sheet". Animals Australia. Archived from the original on July 12, 2010. Retrieved August 29, 2010.
  83. ^ "Chickens Farmed for Meat". Compassion in World Farming. Archived from the original on September 21, 2024. Retrieved February 2, 2024.
  84. ^ "UK Egg Industry Data". Official Egg Info. Archived from the original on December 30, 2016. Retrieved April 25, 2017.
  85. ^ Glenday, Craig (April 26, 2011). Guinness World Records 2011. Jim Pattison Group. p. 286. ISBN 978-0440423102.
  86. ^ a b Browne, Anthony (March 10, 2002). "Ten weeks to live". The Guardian. London. Archived from the original on May 16, 2008. Retrieved April 28, 2010.
  87. ^ Patwardhan, D.; King, A. (2011). "Review: feed withdrawal and non feed withdrawal moult". World's Poultry Science Journal. 67 (2): 253–268. doi:10.1017/s0043933911000286. S2CID 88353703.
  88. ^ Webster, A.B. (2003). "Physiology and behavior of the hen during induced moult". Poultry Science. 82 (6): 992–1002. doi:10.1093/ps/82.6.992. PMID 12817455.
  89. ^ Molino, A.B.; Garcia, E.A.; Berto, D.A.; Pelícia, K.; Silva, A.P.; Vercese, F. (2009). "The Effects of Alternative Forced-Molting Methods on The Performance and Egg Quality of Commercial Layers". Brazilian Journal of Poultry Science. 11 (2): 109–113. doi:10.1590/s1516-635x2009000200006. hdl:11449/14340.
  90. ^ Yousaf, M.; Chaudhry, A.S. (March 1, 2008). "History, changing scenarios and future strategies to induce moulting in laying hens" (PDF). World's Poultry Science Journal. 64 (1): 65–75. doi:10.1017/s0043933907001729. S2CID 34761543. Archived (PDF) from the original on November 24, 2020. Retrieved October 23, 2020.
  91. ^ Fly, Colin (July 27, 2007). "Some homeowners find chickens all the rage". Chicago Tribune.[dead link]
  92. ^ Pollack-Fusi, Mindy (December 16, 2004). "Cooped up in suburbia". Boston Globe. Archived from the original on March 4, 2016. Retrieved June 4, 2020.
  93. ^ Kreilkamp, Ivan (November 25, 2020). "How Caring for Backyard Chickens Stretched My Emotional Muscles". The New York Times. Archived from the original on November 25, 2020.
  94. ^ Boone, Lisa (August 27, 2017). "Chickens will become a beloved pet — just like the family dog". Los Angeles Times. Archived from the original on April 2, 2019. Retrieved April 3, 2019.
  95. ^ Barras, Colin. "Despite what you might think, chickens are not stupid". www.bbc.com. Archived from the original on June 5, 2021. Retrieved September 6, 2020.
  96. ^ United Poultry Concerns. "Providing a Good Home for Chickens". Archived from the original on June 5, 2009. Retrieved May 4, 2009.
  97. ^ "Choosing Your Chickens". Clucks and Chooks. Archived from the original on July 30, 2009.
  98. ^ Raymond Hernandez (April 11, 1995). "A Blood Sport Gets in the Blood; Fans of Cockfighting Don't Understand Its Outlaw Status". The New York Times. New York City Metropolitan Area. Retrieved May 10, 2014.
  99. ^ Crawford, R. D. (1990). Poultry Breeding and Genetics. Elsevier. pp. 10–11. ISBN 978-0444885579. OL 2207173M. Archived from the original on April 18, 2023. Retrieved February 2, 2024.
  100. ^ Lawler, Andrew; Adler, Jerry (June 2012). "How the Chicken Conquered the World". Smithsonian Magazine (June 2012). Archived from the original on October 31, 2019. Retrieved February 2, 2024.
  101. ^ Young, John J.; Tabin, Clifford J. (September 2017). "Saunders's framework for understanding limb development as a platform for investigating limb evolution". Developmental Biology. 429 (2): 401–408. doi:10.1016/j.ydbio.2016.11.005. PMC 5426996. PMID 27840200.
  102. ^ International Chicken Genome Sequencing Consortium (December 9, 2004). "Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution". Nature. 432 (7018): 695–716. Bibcode:2004Natur.432..695C. doi:10.1038/nature03154. PMID 15592404.
  103. ^ Gregory, T. Ryan (September 2005). "Synergy between sequence and size in Large-scale genomics". Nature Reviews Genetics. 6 (9): 699–708. doi:10.1038/nrg1674. PMID 16151375. S2CID 24237594.
  104. ^ Warren, Wesley C.; Hillier, LaDeana W.; Tomlinson, Chad; Minx, Patrick; Kremitzki, Milinn; Graves, Tina; et al. (January 2017). "A New Chicken Genome Assembly Provides Insight into Avian Genome Structure". G3. 7 (1): 109–117. doi:10.1534/g3.116.035923. PMC 5217101. PMID 27852011.
  105. ^ Scientists Find Chickens Retain Ancient Ability to Grow Teeth Archived June 20, 2008, at the Wayback Machine Ammu Kannampilly, ABC News, February 27, 2006. Retrieved October 1, 2007.
  106. ^ Adler, Jerry; Lawler, Andrew (June 2012). "How the Chicken Conquered the World". Smithsonian. Archived from the original on November 3, 2012. Retrieved May 24, 2012.
  107. ^ Encyclopædia Perthensis; Or Universal Dictionary of the Arts, Sciences, Literature, &c. Intended to Supersede the Use of Other Books of Reference. Vol. 1 (2nd ed.). John Brown. 1816. p. 394. Archived from the original on September 21, 2024. Retrieved February 2, 2024.
  108. ^ "Love and Immolation in Argentina". Washington Post. August 16, 1981. Archived from the original on August 27, 2017. Retrieved February 2, 2024.
  109. ^ The Knickerbocker, or The New York Monthly, March 1847, p. 283.
  110. ^ Kellogg, Diane M. (May 22, 2020). "Chickens in Art History". Painting World Magazine. Archived from the original on February 2, 2024. Retrieved February 2, 2024.
  111. ^ Opie, Iona; Opie, Peter (1997) [1951]. The Oxford Dictionary of Nursery Rhymes (2nd ed.). Oxford University Press. p. 128.
  112. ^ Corliss, Richard (December 4, 2000). "Run, Chicken Run!". Time. ISSN 0040-781X. Archived from the original on January 24, 2023. Retrieved March 23, 2023.
  113. ^ "AFI|Catalog". Archived from the original on August 17, 2018. Retrieved August 17, 2018.
  114. ^ "'Chicken' Recipe Simply Divine / Action comedy blends great story, animation". SFGate. June 21, 2000. Archived from the original on June 2, 2021. Retrieved June 2, 2021.
Listen to this article (18 minutes)
Spoken Wikipedia icon
This audio file was created from a revision of this article dated 22 February 2024 (2024-02-22), and does not reflect subsequent edits.