Editing Common ostrich

{{Short description|Species of flightless bird}}
{{Use dmy dates|date=November 2022}}
{{Speciesbox
| name = Common ostrich
| fossil_range = {{Fossil range|15|0}}{{small|Early [[Miocene]] to [[Holocene|Present]]}}
| image = Struthio camelus - Etosha 2014 (3).jpg
| image_caption = [[South African ostrich|South African]] (''S. c. australis'') male (left) and females 
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=BirdLife International |date=2018 |title=''Struthio camelus'' |volume=2018 |page=e.T45020636A132189458 |doi=10.2305/IUCN.UK.2018-2.RLTS.T45020636A132189458.en |access-date=19 November 2021}}</ref>
| status2 = CITES_A1 
| status2_system = CITES 
| status2_ref = <ref name="CITESAppendices">{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=14 January 2022|website=cites.org}}</ref>{{NoteTag|Only populations of Algeria, Burkina Faso, Cameroon, Central African Republic, Chad, Mali, Mauritania, Morocco, Niger, Nigeria, Senegal and Sudan. No other population is included in the CITES Appendices.}}
| genus = Struthio
| species = camelus
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]<ref name="SN"/>
| subdivision_ranks = Subspecies
| subdivision_ref = <ref name="SN"/>
| subdivision = 
*''[[North African ostrich|S. c. camelus]]'' <small>[[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]</small> North African ostrich
*''[[South African ostrich|S. c. australis]]'' <small>[[John Henry Gurney|Gurney]], 1868</small> South African ostrich 
*''[[Masai ostrich|S. c. massaicus]]'' <small>[[Oscar Rudolph Neumann|Neumann]], 1898</small> Masai ostrich
*†''[[Arabian ostrich|S. c. syriacus]]'' <small>[[Lionel Walter Rothschild, 2nd Baron Rothschild|Rothschild]], 1919</small> Arabian ostrich
| range_map = Struthio camelus distribution.svg
| range_map_caption = ''Struthio'' distribution map
{{aligned table|cols=2|style=text-align:left;margin:auto;
|{{Color box|#FFA360|border=darkgray}} ''S. c. camelus''|&nbsp;{{Color box|#FF7166|border=darkgray}} ''S. c. australis''
|{{Color box|#4FF55A|border=darkgray}} ''S. c. massaicus''|&nbsp;{{Color box|#FFFF3B|border=darkgray}} ''S. molybdophanes''
}}<!-- End of legend/key table for caption... -->
|synonyms = {{collapsible list|''Charadrius bidactylus'' <small>[[George Robert Gray|G. R. Gray]], 1847</small>|''Struthio australis'' <small>[[John Henry Gurney Sr.|Gurney]], 1868</small>|''Struthio massaicus'' <small>[[Oscar Rudolph Neumann|Neumann]], 1898</small>|''Struthio camelus spatzi'' <small>[[Erwin Stresemann|Stresemann]], 1926</small>|''Struthio camelus rothschildi'' <small>[[Claude H. B. Grant|Grant]] & [[Cyril Mackworth-Praed|Mackworth-Praed]], 1951</small>
}}
|synonyms_ref = <ref>{{cite book |last1=Gray |first1=George Robert |title=The Genera of Birds Comprising Their Generic Characters, a Notice of the Habits of Each Genus, and an Extensive List of Species Referred to Their Several Genera |date=1849 |publisher=Longman, Brown, Green, and Longmans, Paternoster-Row |location=London, Longman, Brown, Green, and Longmans, Paternoster-Row |edition=3 |url=https://www.biodiversitylibrary.org/item/219683#page/157/mode/1up |access-date=1 December 2024}}</ref><ref>{{cite journal |last1=Gurney |first1=J. H. |title=Notes on Mr. Layard's 'Birds of South Africa'. |journal=The Ibis |date=July 1868 |volume=4 |issue=15 |pages=253-254 |doi=10.1111/j.1474-919x.1868.tb06118.x |url=https://www.biodiversitylibrary.org/page/16341748#page/279/mode/1up |access-date=1 December 2024}}</ref><ref>{{cite journal |last1=Neumann |first1=Oscar |title=Beiträge zur Vogelfauna von Ost- und Central-Afrika |journal=Journal für Ornithologie |date=1898 |volume=46 |page=243 |doi=10.1007/bf02208449 |url=https://www.biodiversitylibrary.org/page/33428623#page/255/mode/1up |access-date=1 December 2024}}</ref><ref>{{cite journal |title=Die Vogelausbeute des Herrn Paul Spatz in Rio de Oro.|last1=Stresemann |first1=Erwin |journal=Ornithologische Monatsberichte |date=1926 |volume=34 |issue=5|page=138}}</ref><ref>{{cite journal |last1=Grant |first1=C. H. B. |last2=Mackworth-Praed |first2=C. W. |title=On the Type Locality of ''Struthio camelus'' Linnaeus, and Description of a New Race |journal=Bulletin of the British Ornithologists' Club |date=1951 |volume=71 |issue=7 |pages=45-46 |url=https://www.biodiversitylibrary.org/item/125665#page/141/mode/1up |access-date=1 December 2024}}</ref>
}}

The '''common ostrich''' ('''''Struthio camelus'''''), or simply '''ostrich''', is a [[species]] of [[flightless bird]] native to certain areas of Africa. It is one of two extant species of ostriches, the only living members of the [[genus]] ''[[Struthio]]'' in the [[ratite]] group of birds. The other is the [[Somali ostrich]] (''Struthio molybdophanes''), which has been recognized as a distinct species by [[BirdLife International]] since 2014, having been previously considered a distinctive subspecies of ostrich.<ref name="SN"/><ref name=IUCN_molybdophanes>{{cite iucn|author= BirdLife International|author-link= BirdLife International| page= e.T22732795A95049558 |title= ''Struthio molybdophanes'' |year= 2016 |access-date= 15 February 2020}}</ref>

The common ostrich belongs to the [[order (biology)|order]] [[Struthioniformes]]. Struthioniformes previously contained all the ratites, such as the [[Kiwi (bird)|kiwis]], [[emu]]s, [[Rhea (bird)|rheas]], and [[Cassowary|cassowaries]]. However, recent genetic analysis has found that the group is not monophyletic, as it is paraphyletic with respect to the [[tinamou]]s, so the ostriches are now classified as the only members of the order.<ref>{{Cite journal|last1=Yuri|first1=Tamaki|last2=Kimball|first2=Rebecca|last3=Harshman|first3=John|last4=Bowie|first4=Rauri|last5=Braun|first5=Michael|last6=Chojnowski|first6=Jena|last7=Han|first7=Kin-Lan|last8=Hackett|first8=Shannon|last9=Huddleston|first9=Christopher|last10=Moore|first10=William|last11=Reddy|first11=Sushma|date=13 March 2013|title=Parsimony and Model-Based Analyses of Indels in Avian Nuclear Genes Reveal Congruent and Incongruent Phylogenetic Signals|journal=Biology|volume=2|issue=1|pages=419–444|doi=10.3390/biology2010419|pmid=24832669|pmc=4009869|issn=2079-7737|doi-access=free}}</ref><ref>{{Cite report |title=Faculty of 1000 evaluation for A phylogenomic study of birds reveals their evolutionary history. |last=Clarke |first=Andrew |date=14 July 2008 |doi=10.3410/f.1115666.571731 |doi-access=free }}</ref> [[Phylogenetic]] studies have shown that it is the sister group to all other members of [[Palaeognathae]], and thus the flighted tinamous are the sister group to the extinct [[moa]].<ref name = "Mitchell2014">{{Cite journal | doi = 10.1126/science.1251981| pmid = 24855267| title = Ancient DNA reveals elephant birds and kiwi are sister taxa and clarifies ratite bird evolution| journal = Science| volume = 344| issue = 6186| pages = 898–900| date = 23 May 2014| last1 = Mitchell | first1 = K. J.| last2 = Llamas | first2 = B.| last3 = Soubrier | first3 = J.| last4 = Rawlence | first4 = N. J.| last5 = Worthy | first5 = T. H.| last6 = Wood | first6 = J.| last7 = Lee | first7 = M. S. Y.| last8 = Cooper | first8 = A.| url = http://dspace.flinders.edu.au/xmlui/bitstream/2328/35953/1/Mitchell_AncientDNA_AM2014.pdf| bibcode = 2014Sci...344..898M| hdl = 2328/35953| s2cid = 206555952| hdl-access = free}}</ref><ref name = "Baker2014">{{Cite journal | doi = 10.1093/molbev/msu153| title = Genomic Support for a Moa-Tinamou Clade and Adaptive Morphological Convergence in Flightless Ratites| journal = Molecular Biology and Evolution| year = 2014| last1 = Baker | first1 = A. J.| last2 = Haddrath | first2 = O.| last3 = McPherson | first3 = J. D.| last4 = Cloutier | first4 = A.| volume=31 | issue = 7| pages=1686–1696 | pmid=24825849| doi-access = free}}</ref> It is distinctive in its appearance, with a long neck and legs, and can run for a long time at a speed of {{cvt|55|km/h}}<ref>{{cite journal |last1=Sellers |first1=W. I. |last2=Manning |first2=P. L. |year=2007 |title=Estimating dinosaur maximum running speeds using evolutionary robotics |journal=Proc. R. Soc. B |volume=274 |issue=1626 |pages=2711–2716 |doi=10.1098/rspb.2007.0846 |pmid=17711833 |pmc=2279215 |url=http://rspb.royalsocietypublishing.org/content/274/1626/2711}}</ref> with short bursts up to about {{cvt|97|km/h}},<ref name="Davies"/> the [[Fastest animals|fastest land speed]] of any bipedal animal and the second fastest of all land animals after the [[cheetah]].<ref name=Doherty/><ref>{{Cite web |date=2022-12-15 |title=Explained: How Fast Can An Ostrich Run {{!}} BirdJoy |url=https://www.birdjoy.org/articles/how-fast-can-an-ostrich-run/ |access-date=2024-10-11 |website=Bird Joy |language=en-US}}</ref> The common ostrich is the [[Largest and heaviest animals|largest living species]] of bird and thus the [[Dinosaur size|largest]] [[Origin of birds|living dinosaur]].<ref>[https://physicsworld.com/a/deducing-how-dinosaurs-moved/ Physics World, February 2, 2017]</ref> It lays [[Ostrich egg|the largest eggs]] of any living bird (the extinct giant elephant bird (''Aepyornis maximus'') of [[Madagascar]] and the south island giant moa (''Dinornis robustus'') of New Zealand laid larger eggs). Ostriches are the most dangerous birds on the planet for humans, with an average of two to three deaths being recorded each year in [[South Africa]].<ref name = "OstrichTrauma">{{Cite journal | doi = 10.1016/j.amsu.2014.12.004| title = Abdominal trauma by ostrich| journal = Annals of Medicine & Surgery| year = 2015 | last1 = Usurelu | first1 = Sergiu | last2 = Bettencourt| first2 = Vanessa | last3 = Melo| first3 =  Gina | volume=4 | issue = 1| pages=41–43| doi-access = free| pmid = 25685344| pmc = 4323753}}</ref>

The common ostrich's diet consists mainly of plant matter, though it also eats [[invertebrate]]s and small reptiles. It lives in nomadic groups of 5 to 50 birds. When threatened, the ostrich will either hide itself by lying flat against the ground or run away. If cornered, it can attack with a kick of its powerful legs. Mating patterns differ by geographical region, but territorial males fight for a harem of two to seven females.

The common ostrich is [[farming|farmed]] around the world, particularly for its feathers, which are decorative and are also used as [[feather duster]]s. Its skin is used for [[Ostrich leather|leather]] products and its meat is marketed commercially, with its leanness a common marketing point.<ref name="Davies"/>

==Description==
The common ostrich is the tallest and heaviest living bird. Males stand {{cvt|2.1|to|2.75|m}} tall and weigh {{cvt|100|to|130|kg}}, whereas females are about {{cvt|1.75|to|1.9|m}} tall and weigh {{cvt|90|to|120|kg}}.<ref name =world>Del Hoyo, Josep, et al. Handbook of the birds of the world. Vol. 1. No. 8. Barcelona: Lynx edicions, 1992.</ref> While exceptional male ostriches (in the nominate subspecies) can weigh up to {{cvt|156.8|kg}}, some specimens in South Africa can only weigh between {{cvt|59.5|to|81.3|kg}}.<ref>Urban, Emil K. "Roberts Birds of Southern Africa." (2007): 1104-1106.</ref> New chicks are [[wiktionary:fawn|fawn]] in color, with dark brown spots.<ref name = Perrins2/> After three months they start to gain their juvenile plumage, which is steadily replaced by adult-like plumage during their second year. At four or five months old, they are already about half the size of an adult bird, and after a year they reach adult height, but not till they are 18 months old will they be fully as heavy as their parents.<ref name =world/>

The feathers of adult males are mostly black, with white [[flight feathers#Primaries|primaries]] and a white tail. However, the tail of one subspecies is buff. Females and young males are grayish-brown and white. The head and neck of both male and female ostriches are nearly bare, with a thin layer of [[Down feather|down]].<ref name="Gilman 1903"/><ref name=Perrins2/> The skin of the female's neck and thighs is pinkish gray, while the male's is gray or pink dependent on subspecies.<ref name=Perrins2/>

<gallery mode="packed">
File:Afrikanischer Strauss Portrait.jpg|Head feathers are a thin layer of down.
File:Ostrich, mouth open.jpg|Long eyelashes protect the eyes.
File:Ostrich foot.jpg|Feet are frequently missing the nail on the outer toe.
File:The Childrens Museum of Indianapolis - Ostrich skull.jpg|Skull
File:OstrichWing.jpg|Claws on the wings
File:Avestruz alta.jpg|alt=Ostrich skeleton
File:Common ostrich (Struthio camelus australis) male running composite.jpg|Male running, [[Namibia]]|alt=Male, [[Namibia]]
</gallery>

The long neck and legs keep their head up to {{cvt|2.8|m}} above the ground, and their eyes are said to be the largest of any land vertebrate {{endash}} {{cvt|50|mm}} in diameter<ref name=Brown/> {{endash}} helping them to see predators at a great distance. The eyes are shaded from sunlight from above.<ref name=Martin2000/><ref name=Martin2001/> However, the head and [[Beak|bill]] are relatively small for the birds' huge size, with the bill measuring {{cvt|12|to|14.3|cm}}.<ref name="Davies"/>

Their skin varies in color depending on the subspecies, with some having light or dark gray skin and others having pinkish or even reddish skin. The strong legs of the common ostrich are unfeathered and show bare skin, with the [[Tarsus (skeleton)|tarsus]] (the lowest upright part of the leg) being covered in scales: red in the male, black in the female. The [[Tarsus (skeleton)|tarsus]] of the common ostrich is the largest of any living bird, measuring {{cvt|39|to|53|cm}} in length.<ref name="Davies"/> The bird is [[didactyl]], having just two toes on each [[Bird feet and legs|foot]] (most birds have four), with the [[nail (anatomy)|nail]] on the larger, inner toe resembling a [[hoof]]. The outer toe has no nail.<ref>{{cite web|url=http://www.thewonderofbirds.com/biology/claws.htm|publisher=TheWonderofBirds.com|title=Bird claws or nails|access-date=22 January 2015}}</ref> The reduced number of toes is an adaptation that appears to aid in running, useful for getting away from predators. Common ostriches can run at a speed over {{cvt|70|km/h}} and can cover {{cvt|3|to|5|m}} in a single stride.<ref>[http://www.sandiegozoo.org/animalbytes/t-ostrich.html San Diego Zoo's Animal Bytes: Ostrich]. Sandiegozoo.org. Retrieved on 21 August 2012.</ref> The wings reach a span of about {{cvt|2|m}}, and the [[Wing chord (biology)|wing chord]] measurement of {{cvt|90|cm}} is around the same size as for the largest flying birds.<ref name="Davies"/>

The feathers lack the tiny hooks that lock together the smooth external feathers of flying birds, and so are soft and fluffy and serve as insulation. Common ostriches can tolerate a wide range of temperatures. In much of their habitat, temperatures vary as much as {{cvt|40|C-change}} between night and day. Their temperature control relies in part on behavioral thermoregulation.  For example, they use their wings to cover the naked skin of the upper legs and flanks to conserve heat, or leave these areas bare to release heat. The wings also function as stabilizers to give better maneuverability when running. Tests have shown that the wings are actively involved in rapid braking, turning, and zigzag maneuvers.<ref>{{cite web|url=http://www.livescience.com/6657-ostrich-wings-explain-mystery-flightless-dinosaurs.html|title=Ostrich Wings Explain Mystery of Flightless Dinosaurs|website=[[Live Science]]|date=30 June 2010}}</ref> They have 50–60 tail feathers, and their wings have 16 primary, four [[alular]], and 20–23 secondary feathers.<ref name="Davies"/>

The common ostrich's [[sternum]] is flat, lacking the [[Keel (bird)|keel]] to which wing muscles attach in flying birds.<ref name="Nell 2003"/> The [[beak]] is flat and broad, with a rounded tip.<ref name="Gilman 1903"/> Like all [[ratites]], the ostrich has no [[Crop (anatomy)|crop]],<ref name=Brand2006/> and it also lacks a [[gallbladder]]<ref name=Marshall/> and the [[caecum]] is {{cvt|71|cm}}. Unlike all other living birds, the common ostrich secretes urine separately from feces.<ref name=coprodeum/> All other birds store the urine and feces combined in the [[coprodeum]], but the ostrich stores the feces in the terminal rectum.<ref name=coprodeum/> They also have unique [[pubic bones]] that are fused to hold their gut. Unlike most birds, the males have a [[Intromittent organ#Birds|copulatory organ]], which is retractable and {{cvt|20|cm}} long. Their [[palate]] differs from other ratites in that the [[Sphenoid bone|sphenoid]] and [[palatal]] bones are unconnected.<ref name="Davies"/>

==Taxonomy==
The common ostrich was originally described by [[Carl Linnaeus]] from Sweden in his 18th-century work, ''[[Systema Naturae]]'' under its current [[Binomial nomenclature|binomial name]].<ref name=Linnaeus/> Its [[genus]] is derived from the [[Late Latin]] ''struthio'' meaning "ostrich". The specific name is an allusion to "strouthokamelos" the [[Ancient Greek]] name for the ostrich, meaning camel-sparrow,<ref>{{cite web |url=https://www.etymonline.com/word/struthious |title=struthious (adj.) |author=Douglas Harper |date=11 December 2013 |website=Online Etymology Dictionary |access-date=14 December 2022}}</ref> the "camel" term referring to its dry habitat.<ref name=Gotch/> Στρουθοκάμηλος is still the modern Greek name for the ostrich.

The common ostrich belongs to the Infraclass ''[[Palaeognathae]],'' commonly known as 
[[ratites]]. Other members include [[rhea (bird)|rheas]], [[emu]]s, [[cassowary|cassowaries]], [[moa]], [[Kiwi (bird)|kiwi]], [[elephant birds]], and [[tinamous]].

===Subspecies===
Four [[subspecies]] are recognized:

{| class="wikitable"
|+ Subspecies of the common ostrich
! Subspecies !! Description !! Image
|-
|'''[[North African ostrich]]''' (''S. c. camelus''), also known as the '''red-necked ostrich''' or '''Barbary ostrich''' || Lives in North Africa. Historically it was the most widespread subspecies, ranging from [[Ethiopia]] and [[Sudan]] in the east throughout the [[Sahel]]<ref name="Clements"/> to [[Senegal]] and [[Mauritania]] in the west, and north to [[Egypt]] and southern [[Morocco]], respectively. It has now disappeared from large parts of this range,<ref name=Thiollay/> and it only remains in six of the 18 countries where it originally occurred, leading some to consider it [[Critically Endangered]].<ref name=SaharaConservation>Sahara Conservation Fund: {{cite web |url=https://saharaconservation.org/north-african-ostrich/ |title=North African Ostrich Recovery Project |date=16 September 2019 |access-date=25 April 2020}}</ref> It is the largest subspecies, at {{cvt|2.74|m}} in height and up to {{cvt|154|kg}} in weight.<ref name="Roots 2006"/> The neck is pinkish-red, the plumage of males is black and white, and the plumage of females is grey.<ref name="Roots 2006"/>

*Northern Africa: [[Algeria]], the [[Central African Republic]], [[Chad]], [[Egypt]], [[Ethiopia]], [[Libya]], [[Mali]], [[Mauritania]], [[Morocco]], [[Sudan]], [[South Sudan]], [[Togo]], and [[Tunisia]]
*Western Africa: [[Benin]], [[Burkina Faso]], [[Cameroon]], [[Ghana]], [[Niger]], [[Nigeria]], and [[Senegal]]
||[[File:Yaen001.jpg|150px]]
|-
|'''[[South African ostrich]]''' (''S. c. australis''), also known as the '''black-necked ostrich''', '''Cape ostrich''', or '''southern ostrich''' || Found south of the [[Zambezi]] and [[Cunene River|Cunene]] Rivers. It is farmed for its meat, [[Ostrich leather|leather]], and feathers in the [[Little Karoo]] area of [[Cape Province]].<ref name=Stocker/>

*Southern Africa: [[Angola]], [[Botswana]], [[Democratic Republic of the Congo]], [[Namibia]], South Africa, [[Zambia]], and [[Zimbabwe]]
||[[File:Ostrich (Struthio camelus) male (13994461256).jpg|150px]]
|-
|'''[[Masai ostrich]]''' (''S. c. massaicus''), also known as the '''pink-necked ostrich''' or '''East African ostrich'''|| It has some small feathers on its head, and its neck and thighs are pink. During the [[mating season]], the male's neck and thighs become brighter. Its range is essentially limited to southern [[Kenya]] and eastern [[Tanzania]]<ref name="Clements" /> and [[Ethiopia]] and parts of southern [[Somalia]].<ref name="Roots 2006"/>

*Eastern Africa: [[Burundi]], the [[Democratic Republic of the Congo]], [[Ethiopia]], [[Kenya]], [[Rwanda]], [[Somalia]], [[Tanzania]], and [[Uganda]]
||[[File:Ostrich Struthio camelus Tanzania 3742 cropped Nevit.jpg|150px]] 
|-
|'''[[Arabian ostrich]]''' {{nowrap|({{dagger}}''S. c. syriacus''),}} also known as the '''Syrian ostrich''' or '''Middle Eastern ostrich'''|| Was formerly very common in the [[Arabian Peninsula]], [[Syria]],<ref name="Clements"/> [[Iraq]], and [[Israel]]i [[Negev]];<ref name="haaretz_ref1">{{Cite news|url=https://www.haaretz.com/2007-12-25/ty-article/the-bitter-fate-of-ostriches-in-the-wild/0000017f-db5a-db5a-a57f-db7af66d0000|title=The Bitter Fate of Ostriches in the Wild|last=Rinat|first=Zafrir|date=December 25, 2007|work=[[Haaretz]]|access-date=November 8, 2023|language=en}}</ref> it became extinct around 1966.

*Western Asia: Iran, Iraq, Israel, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, Syria, the United Arab Emirates, and Yemen 
||[[File:Arabian Ostrich hunt.jpg|150px]]
|-
|}

{| class="wikitable"
|+ Somali ostrich
! Species !! Description !! Image
|-
|'''[[Somali ostrich]]''' (''S. molybdophanes''), also known as the '''blue-necked ostrich''' || Found in southern [[Ethiopia]], northeastern [[Kenya]], and [[Somalia]].<ref name="Clements" /> The neck and thighs are grey-blue, and during the mating season, the male's neck and thighs become brighter and bluer. The females are more brown than those of other subspecies.<ref name="Roots 2006"/> It generally lives in pairs or alone, rather than in flocks. Its range overlaps with ''S. c. massaicus'' in northeastern Kenya.<ref name="Roots 2006"/>

*Northeastern Africa: [[Djibouti]], [[Eritrea]], [[Ethiopia]], [[Kenya]], and [[Somalia]]
||[[File:Struthio molybdophanes.jpg|150px]]
|-
|}
 
Some analyses indicate that the Somali ostrich is now considered a full species; the [[Tree of Life Web Project|Tree of Life Project]], ''[[The Clements Checklist of Birds of the World]]'', [[BirdLife International]], and the [[Birds of the World: Recommended English Names|IOC World Bird List]] recognize it as a different species. A few authorities, including the ''[[Howard and Moore Complete Checklist of the Birds of the World]]'', do not recognize it as separate.<ref name=IUCN_molybdophanes /><ref>Taylor, Joe (4 September 2013). [http://www.birdlife.org/globally-threatened-bird-forums/2013/09/ostrich-struthio-camelus-is-being-split-list-s-molybdophanes-as-near-threatened-or-vulnerable/ "Archived 2014 discussion: Ostrich (''Struthio camelus'') is being split: list S. molybdophanes as Near Threatened or Vulnerable?"], birdlife.org.</ref> [[Mitochondrial DNA]] [[haplotype]] comparisons suggest that it diverged from the other ostriches around 4 [[mya (unit)|mya]] due to the formation of the [[East African Rift]]. Hybridization with the subspecies that evolved southwestwards of its range, ''S. c. massaicus'', has apparently been prevented from occurring on a significant scale by ecological separation; the Somali ostrich prefers bushland where it browses middle-height vegetation for food while the Masai ostrich is, like the other subspecies, a [[grazing]] bird of the open [[savanna]] and ''[[miombo]]'' habitat.<ref name=Freitag/>

The population from [[Río de Oro]] was once separated as ''Struthio camelus spatzi'' because its eggshell pores were shaped like a teardrop and not round. As there is considerable variation of this character and there were no other differences between these birds and adjacent populations of ''S. c. camelus'', the separation is no longer considered valid.<ref name=Bezuidenhout/><ref name =Bezuidenhout2/> However, a study analysing the postcranial skeleton of all living and recently extinct species and subspecies of ostriches appeared to validate ''S. c. spatzi'' based on its unique skeletal proportions.<ref>{{cite journal|author1=Elzanowski, Andrzej|author2=Louchart, Antoine|year=2022|title=Metric variation in the postcranial skeleton of ostriches, ''Struthio'' (Aves: Palaeognathae), with new data on extinct subspecies|journal=Zoological Journal of the Linnean Society|volume=195|issue=1|pages=88–105|url= https://doi.org/10.1093/zoolinnean/zlab049|doi=10.1093/zoolinnean/zlab049}}</ref> This population disappeared in the latter half of the 20th century. There were 19th-century reports of the existence of small ostriches in North Africa; these are referred to as Levaillant's ostrich (''Struthio bidactylus'') but remain a hypothetical form not supported by material evidence.<ref name=Fuller/>

==Distribution and habitat==
Common ostriches formerly occupied Africa north and south of the [[Sahara]], East Africa, Africa south of the rainforest belt, and much of [[Asia Minor]].<ref name="Davies"/> Today common ostriches prefer open land and are native to the [[savanna]]s and [[Sahel]] of Africa, both north and south of the equatorial forest zone.<ref name="Donegan 2002"/> In southwest Africa they inhabit the semi-desert or true desert. Farmed common ostriches in Australia have established [[wiktionary:feral|feral]] populations.<ref name="iucn status 19 November 2021" /><ref>[http://trevorsbirding.com/ostriches-in-australia-and-near-my-home/ Ostriches in Australia – and near my home]. trevorsbirding.com (13 September 2007)</ref> The [[Arabian ostrich]]es in the Near and Middle East were hunted to extinction by the middle of the 20th century. Attempts to reintroduce the common ostrich into Israel have failed.<ref name=haaretz_ref1/> Common ostriches have occasionally been seen inhabiting islands on the [[Dahlak Archipelago]], in the [[Red Sea]] near [[Eritrea]].

Research conducted by the [[Birbal Sahni Institute of Palaeobotany]] in India found molecular evidence that ostriches lived in India 25,000 years ago. DNA tests on fossilized eggshells recovered from eight archaeological sites in the states of Rajasthan, Gujarat and Madhya Pradesh found 92% genetic similarity between the eggshells and the North African ostrich, so these could have been fairly distant relatives.<ref>{{Cite news|url=http://www.thehindu.com/todays-paper/tp-national/ostriches-lived-in-india-once/article17438046.ece|title=Ostriches lived in India once|last=Prasad|first=R.|work=The Hindu|access-date=10 March 2017|language=en}}</ref><ref>{{Cite news|url=http://timesofindia.indiatimes.com/city/lucknow/ostriches-lived-in-india-25000-yrs-ago-bsip-study/articleshow/57565265.cms|title=Ostriches lived in India 25,000 yrs ago: BSIP study - Times of India|work=The Times of India|access-date=10 March 2017}}</ref>

Ostriches are farmed in Australia. Many have escaped, however, and feral ostriches now roam the [[Australian outback]].<ref>{{Cite web|date=September 2018|title=The outback ostriches — Australia's loneliest birds|website=[[Australian Broadcasting Corporation]]|url=https://www.abc.net.au/news/2018-09-02/elusive-ostriches-roam-outback-after-farming-attempts-go-bust/10190990}}</ref>

==Behaviour and ecology==
[[File:FlappingOstriches.jpg|thumb|Two birds "dancing"|alt=Pair "dancing"]]
[[File:Ostriches-Sleep-like-Platypuses-pone.0023203.s003.ogv|thumb|Sleeping, with [[Rapid eye movement sleep|REM sleep]] and [[slow-wave sleep]] phases<ref>{{Cite journal | last1 = Lesku | first1 = J. A. | last2 = Meyer | first2 = L. C. R. | last3 = Fuller | first3 = A. | last4 = Maloney | first4 = S. K. | last5 = Dell'Omo | first5 = G. | last6 = Vyssotski | first6 = A. L. | last7 = Rattenborg | first7 = N. C. | editor1-last = Balaban | editor1-first = Evan | title = Ostriches Sleep like Platypuses | doi = 10.1371/journal.pone.0023203 | journal = PLOS ONE | volume = 6 | issue = 8 | pages = e23203 | year = 2011 | pmid =  21887239| pmc =3160860 | bibcode = 2011PLoSO...623203L | doi-access = free }}</ref>]]

Common ostriches normally spend the winter months in pairs or alone. Only 16 percent of common ostrich sightings were of more than two birds.<ref name="Davies"/> During breeding season and sometimes during extreme rainless periods ostriches live in [[nomad]]ic groups of five to 100 birds (led by a top hen) that often travel together with other [[grazing]] animals, such as zebras or [[antelope]]s.<ref name="Donegan 2002"/> Ostriches are [[Diurnality|diurnal]], but may be active on moonlit nights. They are most active early and late in the day.<ref name="Davies"/> The male common ostrich territory is between {{cvt|2|and|20|km2}}.<ref name=Perrins2/>

[[File:Ostrich group nairobi.jpg|thumb|A large group of around 30 ostriches gathered in Nairobi National Park, Kenya.]]
With their acute eyesight and hearing, common ostriches can sense predators such as lions from far away. When being pursued by a predator, they have been known to reach speeds in excess of {{cvt|70|km/h}},<ref name="Davies"/> or possibly {{cvt|80|km/h}}<ref>Russell, Dale A. "Ostrich dinosaurs from the Late Cretaceous of western Canada."Canadian Journal of Earth Sciences 9.4 (1972): 375-402.</ref> and can maintain a steady speed of {{cvt|50|km/h}}, which makes the common ostrich the world's fastest two-legged animal.<ref name=DesertUSA/><ref name = "Stewart2006">{{cite web
 | last = Stewart | first = D. | title = A Bird Like No Other  | work = [[National Wildlife]]
 | publisher = [[National Wildlife Federation]] | date = 1 August 2006 | access-date = 25 April 2020
 | url = https://www.nwf.org/Magazines/National-Wildlife/2006/A-Bird-Like-No-Other
}}</ref> When lying down and hiding from predators, the birds lay their heads and necks flat on the ground, making them appear like a mound of earth from a distance, aided by the heat haze in their hot, dry habitat.<ref name=Werness/><ref name=Hiskey/>

{{anchor|kicks}}When threatened, common ostriches run away, but they can cause serious injury and death with kicks from their powerful legs.<ref name="Donegan 2002"/> Their legs can only kick forward.<ref name=Halcombe/> The kick from an ostrich can yield {{cvt|225|kgf}}.<ref>{{Cite thesis |last=Jelagat |first=Chemis |date=2009 |title=Studies on the possible causes of losses in Ostrich production in selected ostrich Farms in Kenya |url=http://erepository.uonbi.ac.ke/handle/11295/19110 |website=University of Nairobi|type=Thesis }}</ref>

===Feeding===
They mainly feed on seeds, shrubs, grass, fruit, and flowers;<ref name="Davies"/><ref name=Perrins2/> occasionally they also eat insects such as [[locust]]s, small reptiles such as lizards, and animal remains left by carnivorous predators.<ref name="Donegan 2002"/> Lacking teeth, they swallow pebbles that act as [[gastrolith]]s to grind food in the [[gizzard]]. When eating, they will fill their [[gullet]] with food, which is in turn passed down their esophagus in the form of a ball called a [[Bolus (digestion)|bolus]]. The bolus may be as much as {{cvt|210|mL}}. After passing through the neck (there is no [[Crop (anatomy)|crop]]) the food enters the [[gizzard]] and is worked on by the aforementioned pebbles. The gizzard can hold as much as {{cvt|1300|g}}, of which up to 45% may be sand and pebbles.<ref name=Perrins2/> Common ostriches can go without drinking for several days, using [[metabolic water]] and moisture in ingested plants,<ref name=Maclean/> but they enjoy liquid water and frequently take baths where it is available.<ref name="Donegan 2002"/> They can survive losing up to 25% of their body weight through [[dehydration]].<ref name=Perrins3/>

===Mating===
[[File:Common ostrich mating in ngorongoro.jpg|thumb|Mating in [[Ngorongoro Conservation Area]]]]
[[File:Ostrich with eggs.jpg|thumb|With eggs]]
Common ostriches become [[sexual maturity|sexually mature]] when they are 2 to 4 years old; females mature about six months earlier than males. As with other birds, an individual may [[Iteroparity|reproduce several times over its lifetime]]. The [[mating season]] begins in March or April and ends sometime before September. The mating process differs in different geographical regions. [[Territory (animal)|Territorial]] males typically [[mating call|boom]] (by inflating their neck) in defense of their territory and harem of two to seven hens;<ref name="Bertram 1992"/> the successful male may then mate with several females in the area, but will only form a pair bond with a 'major' female.<ref name="Bertram 1992"/>

The cock performs with his wings, alternating wing beats, until he attracts a mate. They will go to the mating area and he will maintain privacy by driving away all intruders. They graze until their behavior is synchronized, then the feeding becomes secondary and the process takes on a ritualistic appearance. The cock will then excitedly flap alternate wings again and start poking on the ground with his bill. He will then violently flap his wings to symbolically clear out a nest in the soil. Then, while the hen runs a circle around him with lowered wings, he will wind his head in a spiral motion. She will drop to the ground and he will mount for copulation.<ref name="Davies"/> Common ostriches raised entirely by humans may direct their courtship behavior not at other ostriches, but toward their human keepers.<ref name=BBC/>

<gallery mode="packed">
File:Ostriches Kgalagadi Transfrontier Park.jpeg|Only 15% of hatchling chicks reach 1 year of age.
File:Struthio camelus - Strausskueken.jpg|Chick|alt=Ostrich chick standing
File:2014-12-02 12h28 Ostrich Farm anagoria.JPG|Recently hatched from egg|alt=Chick, recently hatched from egg
File:Ostrich hen with chicks, northern Serengeti.jpg|Hen with chicks
File:Struthio camelus -Serengeti, Tanzania -female on nest-8.jpg|Female incubating eggs|alt=Female incubating eggs in a shallow nest on the ground
File:Struthio camelus - strus (2).JPG|Nest
</gallery>

[[File:Struthio camelus MWNH 0028.JPG|frameless|right|upright|alt=Egg]]
[[File:Struthio_camelus_egg.jpg|frameless|right|upright|alt=Fried egg]]
The female common ostrich lays her fertilized [[egg (biology)|eggs]] in a single communal nest, a simple pit, {{cvt|30|to|60|cm}} deep and {{cvt|3|m}} wide,<ref name=Harrison/> scraped in the ground by the male. The dominant female lays her eggs first; when it is time to cover them for incubation, she discards extra eggs from the weaker females, leaving about 20 in most cases.<ref name="Davies"/> A female common ostrich can distinguish her own eggs from the others in a communal nest.<ref name=Bertram1979/> Ostrich eggs are the largest of all eggs,<ref name=Hyde/> though they are actually the smallest eggs relative to the size of the adult bird – on average they are {{cvt|15|cm}} long, {{cvt|13|cm}} wide, and weigh {{cvt|1.4|kg}}, over 20 times the weight of a chicken's egg and only 1 to 4% the size of the female.<ref name=Perrins/> They are glossy cream-colored, with thick shells marked by small pits.<ref name="Nell 2003"/>

The eggs are incubated by the females by day and by the males by night. This uses the coloration of the two sexes to escape detection of the nest.  The drab female blends in with the sand, while the black male is nearly undetectable in the night.<ref name="Nell 2003"/> The [[Avian incubation|incubation]] period is 35 to 45 days, which is rather short compared to other [[ratite]]s. This is believed to be the case due to the high rate of predation.<ref name=Perrins/> Typically, the male defends the hatchlings and teaches them to feed, although males and females cooperate in rearing chicks. Fewer than 10% of nests survive the 9-week period of laying and incubation, and of the surviving chicks, only 15% of those survive to 1 year of age.<ref name=Perrins2/> However, among those common ostriches who survive to adulthood, the species is one of the longest-living bird species. Common ostriches in captivity have lived to 62 years and 7 months.<ref name = "Wood"/>

===Predators===
[[File:Ultime grida della savana (1975) - Cheetah hunting ostrich 2.png|thumb|Young female chased by a cheetah]]
As a flightless species in the rich biozone of the African savanna, the common ostrich faces a variety of formidable predators throughout its life cycle. Animals that prey on ostriches of all ages may include [[cheetah]]s, [[lion]]s, [[leopard]]s, [[African hunting dog]]s, and [[spotted hyena]]s.<ref name="Davies"/> Predators of nests and young common ostriches include [[Lupulella|jackal]]s, various [[birds of prey]], [[warthog]]s, [[mongoose]], and [[Egyptian vulture]]s.<ref name="Bertram 1992"/><ref name=Thouless/> Egyptian vultures have been known to hurl stones at ostrich eggs to crack them open so they can eat their contents.<ref>{{Cite web|url=https://www.researchgate.net/publication/230105897 |title=Egyptian Vultures ''Neophron percnopterus'' and Ostrich ''Struthio camelus'' eggs: the origins of stone-throwing behaviour|year=1987|website=ResearchGate}}</ref>

Due to predation pressure, common ostriches have many antipredator tactics. Though they can deliver formidable kicks, they use their great eyesight and speed to run from most of their predators.<ref name= Cooper/> Since ostriches that have detected predators are almost impossible to catch, most predators will try to ambush an unsuspecting bird using obstructing vegetation or other objects.<ref name="Bertram 1992"/> Some ostriches forage with other ostriches or mammals such as [[wildebeest]]s and zebras to detect predators more efficiently.<ref>Bertram, Brian CR. "Vigilance and group size in ostriches." Animal Behaviour 28.1 (1980): 278-286.</ref><ref name="Roots 2006"/> If the nest or young are threatened, either or both of the parents may create a distraction, feigning injury.<ref name=Perrins/> However, they may sometimes fiercely fight predators, especially when chicks are being defended, and are capable of killing humans, hyenas, and even lions in such confrontations.<ref name = Stewart2006/><ref name=NationalGeog/><ref>Austin, Oliver Luther. "Birds of the world; a survey of the twenty-seven orders and one hundred and fifty-five families." (1961).</ref><ref name=":5">{{cite journal |last1=Hurxthal |first1=Lewis M. |year=1986 |title=Our gang, ostrich style |journal=Natural History |volume=95 |pages=34–41, 94 |url=https://www.naturalhistorymag.com/htmlsite/master.html?https://www.naturalhistorymag.com/htmlsite/editors_pick/1986_12_pick.html }}</ref> In non-native areas, especially on ostrich farms in North America, adult ostriches have no known enemies due to their large size, intimidating presence and behaviour similar to that of overgrown guard dogs, with instances of them attacking and decapitating [[coyote]]s on one occasion.<ref>{{cite web|url=https://www.youtube.com/watch?v=PPQi8eIrYQs|title=Ostrich Decapitates Coyote!|author=Longhorn Lester's|website=YouTube|date=13 November 2023 }}</ref> 

Usually, ostrich hunting is done by male cheetah coalitions in the Kalahari region during the night, when ostrich's vigilance is less effective.<ref>Mills, M. G. L., and Margie Mills. Kalahari cheetahs: adaptations to an arid region. Oxford University Press, 2017.</ref> Cheetahs in other regions rarely hunt ostriches, but an exceptional coalition composed of three [[East African cheetah]]s has been reported in Kenya.<ref name = "Sunquist">Sunquist, Mel, and Fiona Sunquist. Wild cats of the world. University of Chicago Press, 2017.</ref><ref>{{Cite news|url=http://news.bbc.co.uk/earth/hi/earth_news/newsid_8302000/8302054.stm|title = Epic cheetah hunt filmed in HD|date = 12 October 2009}}</ref> Similarly, lions hunt ostriches mainly in the Kalahari region and not in other regions, or take ostriches as only a small percentage of their prey.<ref name = Sunquist/> Overall, due to their speed, vigilance, and possibly dangerous kick, ostriches are usually avoided by most predators, including lions, leopards, wild dogs, and cheetahs.<ref name=Hayward2005>{{Cite journal |last1=Hayward |first1=M. W. |last2=Kerley |first2=G. I. H. |year=2005 |title=Prey preferences of the lion (''Panthera leo'') |journal=Journal of Zoology |volume=267 |issue=3 |pages=309–322 |doi=10.1017/S0952836905007508 |url=http://www.zbs.bialowieza.pl/g2/pdf/1595.pdf |citeseerx=10.1.1.611.8271 }}</ref><ref name=Hayward2006>{{cite journal |last1=Hayward |first1=M.W. |last2=Henschel |first2=P. |last3=O'Brien |first3=J. |last4=Hofmeyr |first4=M. |last5=Balme |first5=G. |last6=Kerley |first6=G. I. H. |title=Prey preferences of the leopard (''Panthera pardus'') |journal=Journal of Zoology |date=2006 |volume=270 |issue=4 |pages=298–313 |doi=10.1111/j.1469-7998.2006.00139.x |url=http://www.ibs.bialowieza.pl/g2/pdf/1596.pdf |access-date=9 August 2021 |archive-date=29 February 2020 |archive-url=https://web.archive.org/web/20200229233750/https://ibs.bialowieza.pl/g2/pdf/1596.pdf |url-status=dead }}</ref><ref>Hayward, M.W., O’Brien, J., Hofmeyer, M. & Kerley, G.I.H.(2006b). Prey preferences of the cheetah (Acinonyx jubatus) (Felidae: Carnivora): morphological limitations or the need to capture rapidly consumable prey before Kleptoparasites arrive? J. Zool. (Lond.) doi: 10.1111/j.1469-7998.2006.00184.x.</ref><ref>Hayward, Matt W., et al. "Prey preferences of the African wild dog Lycaon pictus (Canidae: Carnivora): ecological requirements for conservation." Journal of Mammalogy 87.6 (2006): 1122-1131.</ref> Despite parental care, 90% is typical for chick mortality, most of it caused by predation.<ref name=":5"/>

==Physiology==
===Respiration===
====Anatomy====
[[File:Ostrich Respiratory Anatomy.svg|thumb|Diagrammatic location of the air sacs]]
 
Morphology of the common ostrich [[lung]] indicates that the structure conforms to that of the other [[bird anatomy|avian species]], but still retains parts of its primitive [[ratite]] structure.<ref name=Makanya /> The opening to the respiratory pathway begins with the [[larynx|laryngeal]] cavity lying posterior to the [[posterior nasal apertures|choanae]] within the [[Mouth|buccal cavity]].<ref name=Deeming /> The tip of the tongue then lies [[anatomical terms of location|anterior]] to the choanae, excluding the nasal respiratory pathway from the buccal cavity.<ref name=Deeming /> The trachea lies [[Anatomical terms of location|ventrally]] to the cervical vertebrae extending from the [[larynx]] to the [[Syrinx (bird anatomy)|syrinx]], where the trachea enters the [[thorax]], dividing into two primary [[bronchus|bronchi]], one to each lung, in which they continue directly through to become mesobronchi.<ref name=Deeming /> Ten different air sacs attach to the lungs to form areas for respiration.<ref name=Deeming /> The most [[Anatomical terms of location|posterior]] [[air sacs]] (abdominal and post-thoracic) differ in that the right abdominal air sac is relatively small, lying to the right of the [[mesentery]], and [[Anatomical terms of location|dorsally]] to the liver.<ref name=Deeming /> While the left abdominal air sac is large and lies to the left of the mesentery.<ref name=Deeming /> The connection from the main mesobronchi to the more [[Anatomical terms of location|anterior]] air sacs including the [[clavicle|interclavicular]], lateral clavicular, and pre-thoracic sacs known as the ventrobronchi region. While the [[Anatomical terms of location|caudal]] end of the mesobronchus branches into several dorsobronchi. Together, the ventrobronchi and dorsobronchi are connected by intra-pulmonary airways, the [[bird anatomy|parabronchi]], which form an arcade structure within the lung called the paleopulmo. It is the only structure found in primitive birds such as ratites.<ref name=Deeming />
[[File:Struthio_syrinx.jpg|thumb|The syrinx has simple muscles. The only sounds that can be produced are roars and hisses.]]
The largest air sacs found within the respiratory system are those of the post-thoracic region, while the others decrease in size respectively, the interclavicular (unpaired), abdominal, pre-thoracic, and lateral clavicular sacs.<ref name=Schmidt-Nielsen /> The adult common ostrich lung lacks connective tissue known as interparabronchial septa, which render strength to the non-compliant avian lung in other bird species. Due to this the lack of connective tissue surrounding the parabronchi and adjacent parabronchial lumen, they exchange blood capillaries or [[blood vessel|avascular]] epithelial plates.<ref name=Makanya /> Like mammals, ostrich lungs contain an abundance of type II cells at gas exchange sites; an adaptation for preventing lung collapse during slight volume changes.<ref name=Makanya />

====Function====
The common ostrich is an [[endotherm]] and maintains a body temperature of {{cvt|38.1|-|39.7|C}} in its extreme living temperature conditions, such as the heat of the savanna and desert regions of Africa.<ref name=King/> The ostrich utilizes its respiratory system via a costal pump for ventilation rather than a [[thoracic diaphragm|diaphragmatic pump]] as seen in most mammals.<ref name=Deeming/> Thus, they are able to use a series of air sacs connected to the [[bird anatomy|lungs]]. The use of air sacs forms the basis for the three main avian respiratory characteristics:
# Air is able to flow continuously in one direction through the lung, making it more efficient than the mammalian lung. 
# It provides birds with a large residual volume, allowing them to breathe much more slowly and deeply than a mammal of the same body mass. 
# It provides a large source of air that is used not only for gaseous exchange, but also for the transfer of heat by evaporation.<ref name=Deeming/>

[[File:Struthio camelus portrait Whipsnade Zoo.jpg|frameless|right|alt=Ostrich portrait showing its large eyes and long eyelashes, its flat, broad beak, and its nostrils]]

Inhalation begins at the mouth and the nostrils located at the front of the beak. The air then flows through the anatomical dead space of a highly vascular trachea ({{circa}} {{cvt|78|cm}}) and expansive bronchial system, where it is further conducted to the posterior air sacs.<ref name=zool241/> Air flow through the [[bird anatomy|parabronchi]] of the paleopulmo is in the same direction to the dorsobronchi during inspiration and expiration. Inspired air moves into the respiratory system as a result of the expansion of thoraco abdominal cavity; controlled by [[bird anatomy|inspiratory muscles]]. During expiration, oxygen poor air flows to the anterior air sacs<ref name=Schmidt-Nielsen/> and is expelled by the action of the [[bird anatomy|expiratory muscles]]. The common ostrich air sacs play a key role in respiration, since they are capacious, and increase surface area (as described by the [[Fick Principle]]).<ref name=zool241/> The oxygen rich air flows [[wikt:unidirectional|unidirectionally]] across the respiratory surface of the lungs; providing the blood that has a crosscurrent flow with a high concentration of oxygen.<ref name=zool241/>

To compensate for the large "dead" space, the common ostrich trachea lacks valves to allow faster inspiratory air flow.<ref name=MainaSingh/> In addition, the [[lung volumes|total lung capacity]] of the respiratory system, (including the lungs and ten air sacs) of a {{cvt|100|kg}} ostrich is about {{cvt|15|L|cuin}}, with a [[tidal volume]] ranging from {{cvt|1.2|-|1.5|L|cuin}}.<ref name=Schmidt-Nielsen/><ref name=MainaSingh>{{Cite journal 
| last1 = Maina | first1 = J.N. 
| last2 = Singh | first2 = P. 
| last3 = Moss  | first3 = E.A. 
| doi = 10.1016/j.resp.2009.09.011 
| title = Inspiratory aerodynamic valving occurs in the ostrich, ''Struthio camelus'', lung: A computational fluid dynamics study under resting unsteady state inhalation 
| journal = Respiratory Physiology & Neurobiology 
| volume = 169 
| issue = 3 
| pages = 262–270 
| year = 2009 
| pmid = 19786124 
| s2cid = 70939 
}}</ref> The tidal volume is seen to double resulting in a 16-fold increase in ventilation.<ref name=Deeming/> Overall, ostrich respiration can be thought of as a high velocity-low pressure system.<ref name=Schmidt-Nielsen/> At rest, there is a small pressure difference between the ostrich air sacs and the atmosphere, suggesting simultaneous filling and emptying of the air sacs.<ref name=MainaSingh/>

The increase in respiration rate from the low range to the high range is sudden and occurs in response to [[hyperthermia]]. Birds lack sweat glands, so when placed under stress due to heat, they heavily rely upon increased evaporation from the respiratory system for heat transfer. This rise in [[respiration rate]] however is not necessarily associated with a greater rate of oxygen consumption.<ref name=Deeming/> Therefore, unlike most other birds, the common ostrich is able to dissipate heat through panting without experiencing [[respiratory alkalosis]] by modifying ventilation of the respiratory medium. During [[hyperpnea]] ostriches pant at a respiratory rate of 40–60&nbsp;cycles per minute, versus their resting rate of 6–12&nbsp;cycles per minute.<ref name=Schmidt-Nielsen/> Hot, dry, and moisture lacking properties of the common ostrich respiratory medium affect oxygen's diffusion rate ([[Henry's Law]]).<ref name=zool241>{{cite book |last1=Hill |first1=W.R. |last2=Wyse |first2=A.G. |last3=Anderson |first3=M. |name-list-style=amp |year=2012 |title=Animal Physiology |edition=3rd |publisher=Sinauer Associates |place=Sunderland, MA}}{{page needed|date=November 2013}}</ref>

Common ostriches develop via [[Angiogenesis|Intussusceptive angiogenesis]], a mechanism of [[blood vessel]] formation, characterizing many organs.<ref name=Makanya/> It is not only involved in vasculature expansion, but also in angioadaptation<ref>{{cite journal |pmid=12270956 |year=2002 |last1=Zakrzewicz |first1=A. |last2=Secomb |first2=T.W. |last3=Pries |first3=A.R. |title=Angioadaptation: Keeping the vascular system in shape |volume=17 |issue=5 |pages=197–201 |journal=News in Physiological Sciences |doi=10.1152/nips.01395.2001 }}</ref> of vessels to meet physiological requirements.<ref name=Makanya /> The use of such mechanisms demonstrates an increase in the later stages of [[lung]] development, along with elaborate parabronchial [[vasculature]], and reorientation of the [[gas exchange]] blood capillaries to establish the crosscurrent system at the blood-gas barrier.<ref name=Makanya/> The [[blood-air barrier|blood–gas barrier]] (BGB) of their lung tissue is thick. The advantage of this thick barrier may be protection from damage by large volumes of blood flow in times of activity, such as running,<ref name=Maina/> since air is pumped by the air sacs rather than the lung itself. As a result, the [[capillaries]] in the parabronchi have thinner walls, permitting more efficient gaseous exchange.<ref name=Deeming/> In combination with separate pulmonary and systemic circulatory systems, it helps to reduce stress on the BGB.<ref name=Makanya/>

===Circulation===

====Heart anatomy====

The common ostrich heart is a closed system, contractile chamber. It is composed of [[myogenic]] muscular tissue associated with heart contraction features. There is a double circulatory plan in place possessing both a [[pulmonary circuit]] and systemic circuit.<ref name=zool241 />

The common ostrich's heart has similar features to other avian species, like having a [[Cone|conically]] shaped heart and being enclosed by a [[Fibrous pericardium|pericardium]] layer.<ref name=heartanatomy>{{cite journal|author=Tadjalli, M.|author2=Ghazi, S. R.|author3=Parto, P.|name-list-style=amp|url=http://ijvr.shirazu.ac.ir/article_1084_16026a1de1a104067949c765dc03ca9f.pdf|year=2009|title=Gross anatomy of the heart in Ostrich (''Struthio camelus'')|journal=Iran J. Vet. Res.|volume=10|issue=1|pages=21–7|access-date=17 March 2017|archive-date=18 March 2017|archive-url=https://web.archive.org/web/20170318004059/http://ijvr.shirazu.ac.ir/article_1084_16026a1de1a104067949c765dc03ca9f.pdf|url-status=dead}}</ref> Moreover, similarities also include a larger [[right atrium]] volume and a thicker [[left ventricle]] to fulfil the [[Circulatory system|systemic circuit]].<ref name=heartanatomy /> The ostrich heart has three features that are absent in related birds: 
# The right [[Heart valve|atrioventricular valve]] is fixed to the [[interventricular septum]], by a thick muscular stock, which prevents back-flow of blood into the atrium when [[Cardiac cycle|ventricular systole]] is occurring.<ref name=heartanatomy /> In the [[fowl]] this valve is only connected by a short septal attachment.<ref name=heartanatomy /> 
# [[Pulmonary vein]]s attach to the left atrium separately, and also the opening to the pulmonary veins are separated by a septum.<ref name=heartanatomy /> 
# [[Septomarginal trabecula|Moderator bands]], full of [[Purkinje fibers]], are found in different locations in the left and right ventricles.<ref name=heartanatomy /> These bands are associated with contractions of the heart and suggests this difference causes the left ventricle to contract harder to create more pressure for a completed circulation of blood around the body.<ref name=heartanatomy />

The [[atrioventricular node]] position differs from other fowl. It is located in the [[endocardium]] of the atrial surface of the right atrioventricular valve. It is not covered by connective tissue, which is characteristic of vertebrate heart anatomy. It also contains fewer [[myofibrils]] than usual myocardial cells. The AV node connects the atrial and ventricular chambers. It functions to carry the electrical impulse from the atria to the ventricle. Upon view, the myocardial cells are observed to have large densely packed chromosomes within the nucleus.<ref name =Parto/>

The [[Coronary circulation|coronary]] [[arteries]] start in the right and left aortic sinus and provide blood to the heart muscle in a similar fashion to most other vertebrates.<ref name =Henriquez/> Other domestic birds capable of flight have three or more [[Coronary circulation|coronary]] arteries that supply blood to the heart muscle. The blood supply by the coronary arteries are fashioned starting as a large branch over the surface of the heart. It then moves along the [[coronary groove]] and continues on into the tissue as [[Ventricle (heart)|interventricular]] branches toward the [[apex of the heart]]. The [[atrium (heart)|atria]], [[ventricle (heart)|ventricle]]s, and [[septum]] are supplied of blood by this modality. The deep branches of the coronary arteries found within the heart tissue are small and supply the interventricular and right [[atrioventricular node|atrioventricular]] valve with blood nutrients for which to carry out their processes. The interatrial artery of the ostrich is small in size and exclusively supplies blood to only part of the left auricle and interatrial [[septum]].<ref name =Bezuidenhout/><ref name =Bezuidenhout2/>

These [[Purkinje fibers]] (p-fibers) found in the hearts moderator bands are a specialized cardiac muscle fiber that causes the heart to contract.<ref name=purkinje>{{cite journal|author=Parto, P.|author2=Tadjalli, M.|author3=Ghazi, S. R.|author4=Salamat, M. A.|name-list-style=amp|year=2013|title=Distribution and Structure of Purkinje Fibers in the Heart of Ostrich (''Struthio camelus'') with the Special References on the Ultrastructure|journal= International Journal of Zoology|doi=10.1155/2013/293643|volume=2013|pages=1–6|doi-access=free}}</ref> The Purkinje cells are mostly found within both the endocardium and the sub-endocardium.<ref name=purkinje /> The [[sinoatrial node]] shows a small concentration of Purkinje fibers, however, continuing through the [[Electrical conduction system of the heart|conducting pathway]] of the heart the [[bundle of his]] shows the highest amount of these Purkinje fibers.<ref name=purkinje />

====Blood composition====

The [[red blood cell]] count per unit volume in the ostrich is about 40% of that of a human; however, the red blood cells of the ostrich are about three times larger than the red blood cells of a human.<ref name=metabolism1>{{Cite journal | last1 = Isaacks | first1 = R. | last2 = Harkness | first2 = D. | last3 = Sampsell | first3 = J. | last4 = Adler | first4 = S. | last5 = Roth | first5 = C. | last6 = Kim | first6 = P. | last7 = Goldman | first7 = R. | doi = 10.1111/j.1432-1033.1977.tb11700.x | title = Studies on Avian Erythrocyte Metabolism. Inositol Tetrakisphosphate: The Major Phosphate Compound in the Erythrocytes of the Ostrich (Struthio camelus camelus) | journal = European Journal of Biochemistry | volume = 77 | issue = 3 | pages = 567–574 | year = 1977 | pmid =  19258| doi-access = free }}</ref> The blood oxygen affinity, known as [[P50 (pressure)|P<sub>50</sub>]], is higher than that of both humans and similar avian species.<ref name=metabolism1 /> The reason for this decreased [[Oxygen–haemoglobin dissociation curve|oxygen affinity]] is due to the hemoglobin configuration found in common ostrich blood.<ref name=metabolism1 /> The common ostrich's [[tetramer]] is composed of [[hemoglobin]] type A and D, compared to typical mammalian tetramers composed of hemoglobin type A and B; hemoglobin D configuration causes a decreased oxygen affinity at the site of the respiratory surface.<ref name=metabolism1 />

During the [[embryo]]nic stage, [[Hemoglobin E]] is present.<ref name=metabolism2>{{Cite journal 
| doi = 10.1016/S0300-9629(76)80046-1 
| last1 = Isaacks | first1 = R. E. 
| last2 = Harkness | first2 = D. R. 
| last3 = Froeman | first3 = G. A. 
| last4 = Goldman | first4 = P. H. 
| last5 = Adler | first5 = J. L. 
| last6 = Sussman | first6 = S. A. 
| last7 = Roth | first7 = S. 
| title = Studies on avian erythrocyte metabolism—II. Relationship between the major phosphorylated metabolic intermediates and oxygen affinity of whole blood in chick embryos and chicks 
| journal = Comparative Biochemistry and Physiology A 
| volume = 53 
| issue = 2 
| pages = 151–156 
| year = 1976 
| pmid = 2411
}}</ref> This subtype increases oxygen affinity in order to transport oxygen across the allantoic membrane of the embryo.<ref name=metabolism2 /> This can be attributed to the high metabolic need of the developing embryo, thus high oxygen affinity serves to satisfy this demand. When the chick hatches hemoglobin E diminishes while hemoglobin A and D increase in concentration.<ref name=metabolism2 /> This shift in hemoglobin concentration results in both decreased oxygen affinity and increased P<sub>50</sub> value.<ref name=metabolism2 />

Furthermore, the P<sub>50</sub> value is influenced by differing organic modulators.<ref name=metabolism2 /> In the typical mammalian RBC 2,3 – DPG causes a lower affinity for oxygen. 2,3- DPG constitutes approximately 42–47%, of the cells phosphate of the embryonic ostrich.<ref name=metabolism2 /> However, the adult ostrich have no traceable 2,3- DPG.In place of 2,3-DPG the ostrich uses inositol [[polyphosphate]]s (IPP), which vary from 1–6 phosphates per molecule.<ref name=metabolism2 /> In relation to the IPP, the ostrich also uses [[Adenosine triphosphate|ATP]] to lower oxygen affinity.<ref name=metabolism2 /> ATP has a consistent concentration of phosphate in the cell<ref name=metabolism2 /> {{endash}} around 31% at [[incubation period]]s and dropping to 16–20% in 36-day-old chicks.<ref name=metabolism2 /> However, IPP has low concentrations, around 4%, of total phosphate concentration in embryonic stages, but the IPP concentration jumps to 60% of total phosphate of the cell.<ref name=metabolism2 /> The majority of phosphate concentration switches from 2,3- DPG to IPP, suggesting the result of the overall low oxygen affinity is due to these varying polyphosphates.<ref name=metabolism2 />

Concerning immunological adaptation, it was discovered that wild common ostriches have a pronounced non-specific immunity defense, with blood content reflecting high values of [[lysosome]] and [[phagocyte]] cells in medium. This is in contrast to domesticated ostriches, who in captivity develop high concentration of [[immunoglobulin]] [[antibodies]] in their circulation, indicating an acquired immunological response. It is suggested that this immunological adaptability may allow this species to have a high success rate of survival in variable environmental settings.<ref name= Cooper/>

===Osmoregulation===

====Physiological challenges====
The common ostrich is a [[Xerocole|xeric]] animal, due to the fact that it lives in habitats that are both dry and hot.<ref name=zool241 /> Water is scarce in dry and hot environments, and this poses a challenge to the ostrich's water consumption. Also the ostrich is a ground bird and cannot fly to find water sources, which poses a further challenge. Because of their size, common ostriches cannot easily escape the heat of their environment; however, they dehydrate less than their small bird counterparts because of their small [[surface area to volume ratio]].<ref name=Skadhaugeetal>{{cite journal|last=Skadhauge|first=E|author2=Warüi CN |author3=Kamau JM |author4=Maloiy GM |title=Function of the lower intestine and osmoregulation in the ostrich: preliminary anatomical and physiological observations|journal=Quarterly Journal of Experimental Physiology|year=1984|volume=69|issue=4|pages=809–18|pmid=6514998 |doi=10.1113/expphysiol.1984.sp002870|doi-access=free}}</ref> Hot, arid habitats pose osmotic stress, such as [[dehydration]], which triggers the common ostrich's [[Homeostasis|homeostatic]] response to osmoregulate.

====System overview====
The common ostrich is well-adapted to hot, arid environments through specialization of [[excretory]] organs. The common ostrich has an extremely long and developed [[colon (anatomy)|colon]] {{endash}} a length of approximately {{cvt|11|-|13|m}} {{endash}} between the [http://medical-dictionary.thefreedictionary.com/coprodeum coprodeum] and the paired [[Pyloric caeca|caeca]], which are around {{cvt|80|cm}} long.<ref name=Skadhaugeetal /> A well-developed caeca is also found and, in combination with the [[rectum]], forms the [[microbial fermentation]] chambers used for [[carbohydrate]] breakdown.<ref name=Skadhaugeetal /> The [[catabolism]] of carbohydrates produces around {{cvt|0.56|g|gr}} of water that can be used internally.<ref name=zool241 /> The majority of their [[urine]] is stored in the coprodeum, and the [[feces]] are separately stored in the terminal colon.<ref name=Skadhaugeetal /> The coprodeum is located ventral to the terminal rectum and [[urodeum]] (where the [[ureters]] open).<ref name=Deeming /> Found between the terminal rectum and coprodeum is a strong sphincter.<ref name=Deeming /> The coprodeum and cloaca are the main osmoregulatory mechanisms used for the regulation and reabsorption of ions and water, or net water conservation.<ref name=Deeming /> As expected in a species inhabiting arid regions, dehydration causes a reduction in fecal water, or dry feces.<ref name=Deeming /> This reduction is believed to be caused by high levels of plasma [[aldosterone]], which leads to rectal absorption of sodium and water.<ref name=Deeming /> Also expected is the production of [[hyperosmotic]] urine; cloacal urine has been found to be 800 [[Osmole (unit)|mOsm]].<ref name=Deeming /> The U:P (urine:plasma) ratio of the common ostrich is therefore greater than one. Diffusion of water to the coprodeum (where urine is stored) from plasma across the [[epithelium]] is voided.<ref name=Deeming /> This void is believed to be caused by the thick [[mucosal]] layering of the coprodeum.<ref name=Deeming />

Common ostriches have two [[kidney]]s, which are chocolate brown in color, are granular in texture, and lie in a depression in the [[bird anatomy|pelvic cavity]] of the dorsal wall.<ref name=Shanawany /> They are covered by [[peritoneum]] and a layer of fat.<ref name=Deeming /> Each kidney is about {{cvt|300|mm}} long, {{cvt|70|mm}} wide, and divided into a [[Anatomical terms of location|cranial]], middle, and [[caudal (anatomical term)|caudal]] sections by large veins.<ref name=Deeming /> The caudal section is the largest, extending into the middle of the pelvis.<ref name=Deeming /> The [[ureters]] leave the ventral caudomedial surface and continue caudally, near the midline into the opening of the urodeum of the cloaca.<ref name=Deeming /> Although there is no bladder, a dilated pouch of ureter stores the urine until it is secreted continuously down from the [[ureter]]s to the urodeum until discharged.<ref name=Shanawany>{{cite book|last=Shanawany|first=M.M.|title=Ostrich Production Systems|year=1999|publisher=Food and Agriculture Organization of the United Nations|isbn=978-92-5-104300-4|page=32|url=https://books.google.com/books?id=BfjUW8ZVinkC&pg=PA253}}</ref>

=====Kidney function=====

Common ostrich kidneys are fairly large and so are able to hold significant amounts of [[solutes]]. Hence, common ostriches drink relatively large volumes of water daily and [[excretion|excrete]] generous quantities of highly concentrated [[urine osmolality|urine]]. It is when drinking water is unavailable or withdrawn that the urine becomes highly concentrated with [[uric acid|uric acid and urates]].<ref name=Deeming /> It seems that common ostriches who normally drink relatively large amounts of water tend to rely on [[renal function|renal conservation]] of water within the kidney system when drinking water is scarce. Though there have been no official detailed [[renal function|renal studies]] conducted<ref>{{cite web |last=Bennett |first=Darin C. |author2=Yutaka Karasawa |title=Effect of Protein Intake on Kidney Function in Adult Female Ostriches (''Struthio Camelus'') |year=2003 |pages=vii |url=http://www.publish.csiro.au/?act=view_file&file_id=EAv48n10posters.pdf}}</ref> on the [[Hagen-Poiseuille equation|flow rate]] ([[Hagen-Poiseuille equation|Poiseuille's Law]]) and composition of the ureteral urine in the ostrich, knowledge of [[renal function]] has been based on samples of [[urine|cloacal urine]], and samples or quantitative collections of [[urine|voided urine]].<ref name=Deeming /> Studies have shown that the amount of water intake and [[dehydration]] impacts the [[plasma osmolality]] and [[urine osmolality]] within various sized ostriches. During a normal hydration state of the kidneys, young ostriches tend to have a measured plasma osmolality of 284 [[mOsm]] and urine osmolality of 62 mOsm. Adults have higher rates with a plasma osmolality of 330 mOsm and urine osmolality of 163 mOsm. The [[osmolality]] of both plasma and urine can alter in regards to whether there is an excess or depleted amount of water present within the kidneys. An interesting fact of common ostriches is that when water is freely available, the urine osmolality can reduce to 60–70 [[mOsm]], not losing any necessary solutes from the kidneys when excess water is excreted.<ref name=Deeming /> Dehydrated or salt-loaded ostriches can reach a maximal urine osmolality of approximately 800 mOsm. When the plasma osmolality has been measured simultaneously with the maximal osmotic urine, it is seen that the urine:plasma ratio is 2.6:1, the highest encountered among avian species.<ref name=Deeming /> Along with dehydration, there is also a reduction in [[Hagen-Poiseuille equation|flow rate]] from 20 L·d<sup>−1</sup> to only 0.3–0.5 L·d<sup>−1</sup>.

In mammals and common ostriches, the increase of the [[renal function|glomerular filtration rate (GFR)]] and [[urine flow rate| urine flow rate (UFR)]] is due to a high protein diets. As seen in various studies, scientists have measured [[clearance (medicine)|clearance of]] [[creatinine]], a fairly reliable marker of glomerular filtration rate (GFR).<ref name=Deeming /> It has been seen that during normal hydration within the kidneys, the glomerular filtration rate is approximately 92&nbsp;ml/min. However, when an ostrich experiences [[dehydration]] for at least 48 hours (2 days), this value diminishes to only 25% of the hydrated GFR rate. Thus in response to the dehydration, ostrich kidneys [[secretion|secrete]] small amounts of very viscous glomerular filtrates that have not been broken down and return them to the [[circulatory system]] through [[blood vessel]]s. The reduction of GFR during dehydration is extremely high and so the fractional excretion of water (urine flow rate as a percentage of GFR) drops down from 15% at normal hydration to 1% during dehydration.<ref name=Deeming />

=====Water intake and turnover=====

Common ostriches employ adaptive features to manage the dry heat and [[solar radiation]] in their habitat.  Ostriches will drink available water; however, they are limited in accessing water by being flightless. They are also able to harvest water through dietary means, consuming plants such as the ''[[Euphorbia heterochroma]]'' that hold up to 87% water.<ref name=Deeming />

Water mass accounts for 68% of body mass in adult common ostriches; this is down from 84% water mass in 35-day-old chicks. The differing degrees of water retention are thought to be a result of varying body fat mass.<ref name=Deeming /> In comparison to smaller birds ostriches have a lower evaporative water loss resulting from their small body surface area per unit weight.<ref name=zool241 />

When heat stress is at its maximum, common ostriches are able to recover evaporative loss by using a [[metabolic water]] mechanism to counter the loss by urine, feces, and respiratory evaporation.  An experiment to determine the primary source of water intake in the ostrich indicated that while the ostrich does employ a [[metabolic water]] production mechanism as a source of hydration, the most important source of water is food. When ostriches were restricted to the no food or water condition, the metabolic water production was only 0.5&nbsp;L·d<sup>−1</sup>, while total water lost to urine, feces, and evaporation was 2.3&nbsp;L·d<sup>−1</sup>. When the birds were given both water and food, total water gain was 8.5&nbsp;L·d<sup>−1</sup>. In the food only condition total water gain was 10.1&nbsp;L·d<sup>−1</sup>. These results show that the [[metabolic water]] mechanism is not able to sustain water loss independently and that food intake, specifically of plants with a high water content such as ''Euphorbia heterochroma'', is necessary to overcome water loss challenges in the common ostrich's arid habitat.<ref name=Deeming />

In times of water deprivation, urine [[electrolyte]] and [[osmotic concentration]] increases while urination rate decreases. Under these conditions [[urine]] [[solute]]:plasma ratio is approximately 2.5, or [[hyperosmotic]]; that is to say that the ratio of solutes to water in the plasma is shifted down whereby reducing osmotic pressure in the plasma. Water is then able to be held back from [[excretion]], keeping the ostrich hydrated, while the passed urine contains higher concentrations of solute. This mechanism exemplifies how renal function facilitates water retention during periods of dehydration stress.<ref name=zool241 /><ref name="Withers" />

=====Nasal glands=====
A number of avian species use [[Salt gland|nasal salt glands]], alongside their kidneys, to control [[Tonicity|hypertonicity]] in their [[blood plasma]].<ref name=saltglands>{{cite journal|title=Saline-Infusion-Induced Increase in Plasma osmolality Do Not Stimulate Nasal Gland Secretion in the Ostrich (''Struthio camelus'') |journal=Physiological Zoology|jstor=30163924|year=1995|volume=68|issue=1|pages=164–175|last1=Gray|first1=David A.|last2=Brown|first2=Christopher R.|doi=10.1086/physzool.68.1.30163924|s2cid=85890608}}</ref> However, the common ostrich shows no nasal glandular function in regard to this homeostatic process.<ref name=saltglands /> Even in a state of dehydration, which increases the [[Osmotic concentration|osmolality]] of the blood, nasal salt glands show no sizeable contribution of salt elimination.<ref name=saltglands /> Also, the overall mass of the glands was less than that of the duck's nasal gland.<ref name=saltglands /> The common ostrich, having a heavier body weight, should have larger, heavier nasal glands to more effectively excrete salt from a larger volume of blood, but this is not the case. These unequal proportions contribute to the assumption that the common ostrich's nasal glands do not play any role in salt excretion.

=====Biochemistry=====
The majority of the common ostrich's internal solutes are made up of [[sodium]] ions ({{chem2|Na(+)}}), [[potassium]] ions ({{chem2|K(+)}}), [[chloride]] ions ({{chem2|Cl(-)}}), total [[short-chain fatty acid]]s (SCFA), and [[acetate]].<ref name=Skadhaugeetal /> The caecum contains a high water concentration with reduced levels nearing the terminal colon and exhibits a rapid fall in {{chem2|Na(+)}} concentrations and small changes in {{chem2|K(+)}} and {{chem2|Cl(-)}}.<ref name=Skadhaugeetal /> 
The colon is divided into three sections and takes part in solute absorption. The upper colon largely absorbs {{chem2|Na(+)}} and SCFA and partially absorbs KCl.<ref name=Skadhaugeetal /> The middle colon absorbs {{chem2|Na(+)}} and SCFA, with little net transfer of K<sup>+</sup> and Cl<sup>−</sup>.<ref name=Skadhaugeetal /> The lower colon then slightly absorbs {{chem2|Na(+)}} and water and secretes {{chem2|K(+)}}. There is no net movements of {{chem2|Cl(-)}} and SCFA found in the lower colon.<ref name=Skadhaugeetal />

When the common ostrich is in a dehydrated state, plasma osmolality, {{chem2|Na(+)}}, {{chem2|K(+)}}, and {{chem2|Cl(-)}} ions all increase; however, {{chem2|K(+)}} ions return to controlled concentration.<ref name=hormones>{{cite journal |doi=10.1016/0300-9629(88)91088-2 |title=Plasma arginine vasotocin and angiotensin II in the water deprived common ostrich (''Struthio camelus'') |year=1988 |last1=Gray |first1=D.A. |last2=Naudé |first2=R.J. |last3=Erasmus |first3=T. |journal=Comparative Biochemistry and Physiology A |volume=89 |issue=2 |pages=251–256}}</ref> The common ostrich also experiences an increase in [[haematocrit]], resulting in a [[Hypovolemia|hypovolemic state]].<ref name=hormones /> Two antidiuretic hormones, [[Vasopressin|Arginine vasotocin (AVT)]] and [[angiotensin]] (AII), are increased in blood plasma as a response to [[hyperosmolality]] and [[hypovolemia]].<ref name=hormones /> AVT triggers [[Vasopressin|antidiuretic hormone]] (ADH) which targets the [[nephrons]] of the kidney.<ref name=zool241 /> ADH causes a reabsorption of water from the lumen of the [[nephron]] to the [[extracellular fluid]] osmotically.<ref name=zool241 /> These extracellular fluids then drain into blood vessels, causing a rehydrating effect.<ref name=zool241 /> This drainage prevents loss of water by both lowering volume and increasing concentration of the urine.<ref name=zool241 /> Angiotensin, on the other hand, causes [[vasoconstriction]] on the systemic arterioles and acts as a [[dipsogen]] for ostriches.<ref name=zool241 /> Both of these antidiuretic hormones work together to maintain water levels in the body that would normally be lost due to the osmotic stress of the arid environment.

Ostriches are [[uricotelic]], excreting nitrogen in the form of [[uric acid]] and related derivatives.<ref name=zool241 /> Uric acid's low solubility in water gives a semi-solid paste consistency to the ostrich's nitrogenous waste.<ref name=zool241 />

===Thermoregulation===

Common ostriches are [[Homeothermy|homeothermic]] [[endotherm]]s; they regulate a constant body temperature via regulating their metabolic heat rate.<ref name=zool241 /> They closely regulate their core body temperature, but their [[appendage]]s may be cooler in comparison as found with regulating species.<ref name=zool241 /> The temperature of their beak, neck surfaces, lower legs, feet, and toes are regulated through heat exchange with the environment.<ref name=polly /> Up to 40% of their produced [[Warm-blooded|metabolic heat]] is [[Dissipation|dissipated]] across these structures, which account for about 12% of their total surface area.<ref name=polly>{{cite journal|author1=Polly K.|author2=Phillips |author3=Sanborn Allen F. |name-list-style=amp |doi=10.1016/0306-4565(94)90042-6|title=An infrared, thermographic study of surface temperature in three ratites: Ostrich, emu and double-wattled cassowary|year=1994|journal=Journal of Thermal Biology|volume=19|issue=6|pages=423–430 |bibcode=1994JTBio..19..423P }}</ref> Total evaporative water loss (TEWL) is statistically lower in the common ostrich than in membering ratites.<ref name=Mitchell />

As ambient temperature increases, dry heat loss decreases, but evaporative heat loss increases because of increased [[Respiration (physiology)|respiration]].<ref name=polly /> As ostriches experience high ambient temperatures, circa {{cvt|50|C}}, they become slightly hyperthermic; however, they can maintain a stable body temperature, around {{cvt|40|C}}, for up to 8 hours in these conditions.<ref name=Schmidt-Nielsen/> When dehydrated, the common ostrich minimizes water loss, causing the body temperature to increase further.<ref name=Schmidt-Nielsen/> When the body heat is allowed to increase the [[temperature gradient]] between the common ostrich and ambient heat is [[Thermodynamic equilibrium|equilibrated]].<ref name=zool241 />

====Physical adaptations====

Common ostriches have developed a comprehensive set of behavioral adaptations for [[thermoregulation]], such as altering their feathers.<ref name=Deeming /> Common ostriches display a feather fluffing behavior that aids them in thermoregulation by regulating [[Convection (heat transfer)|convective heat loss]] at high ambient temperatures.<ref name=polly /> They may also physically seek out shade in times of high ambient temperatures. When feather fluffing, they contract their muscles to raise their feathers to increase the air space next to their skin.<ref name=zool241 /> This air space provides an insulating thickness of {{cvt|7|cm}}.<ref>Mitchell</ref> The ostrich will also expose the thermal windows of their unfeathered skin to enhance convective and radiative loss in times of heat stress.<ref name=Mitchell>{{cite journal|last=Mitchell|first=Malcolm|title=Ostrich Welfare and Transport|journal=Ostrich Welfare|series=Ratite Science Newsletter|pages=1–4|url=http://www.worldpoultry.net/PageFiles/28775/001_boerderij-download-WP6727D01.pdf|access-date=28 December 2013|archive-date=28 December 2013|archive-url=https://web.archive.org/web/20131228103741/http://www.worldpoultry.net/PageFiles/28775/001_boerderij-download-WP6727D01.pdf|url-status=dead}}</ref> At higher ambient temperatures lower appendage temperature increases to {{cvt|5|C-change}} difference from ambient temperature.<ref name=polly /> Neck surfaces are around {{cvt|6|-|7|C-change}} difference at most ambient temperatures, except when temperatures are around {{cvt|25|C}} it was only {{cvt|4|C-change}} above ambient.<ref name=polly />

At low ambient temperatures the common ostrich utilizes feather flattening, which conserves body heat through insulation. The low [[Thermal conduction|conductance coefficient]] of air allows less heat to be lost to the environment.<ref name=zool241 /> This flattening behavior compensate for common ostrich's rather poor cutaneous evaporative water loss (CEWL).<ref name=Louw>{{cite journal|last=Louw|first=Gideon|author2=Belonje, Coetzee|title=Renal Function, Respiration, Heart Rate and Thermoregulation in the Ostrich (''Struthio Camelus'')|journal=Scient. Pap. Namib Desert Res. STN|year=1969|volume=42|pages=43–54|url=http://www.the-eis.com/data/literature/Louw_1969_sci_pap_NDRS_ostrich.pdf|access-date=29 November 2013}}</ref> These feather-heavy areas such as the body, thighs, and wings do not usually vary much from ambient temperatures due to this behavioural controls.<ref name=polly /> This ostrich will also cover its legs to reduce heat loss to the environment, along with undergoing [[piloerection]] and [[shiver]]ing when faced with low ambient temperatures.

====Internal adaptations====
The use of [[Countercurrent exchange|countercurrent]] heat exchange with blood flow allows for regulated conservation/ elimination of heat of appendages.<ref name=zool241/> When ambient temperatures are low, [[Heterothermy|heterotherms]] will constrict their arterioles to reduce heat loss along skin surfaces.<ref name=zool241/> The reverse occurs at high ambient temperatures, arterioles [[Vasodilation|dilate]] to increase heat loss.<ref name=zool241/>
 
At [[Room temperature|ambient temperatures]] below their body temperatures ([[thermal neutral zone]] (TNZ)), common ostriches decrease body surface temperatures so that heat loss occurs only across about 10% of total surface area.<ref name=polly/> This 10% include critical areas that require blood flow to remain high to prevent freezing, such as their eyes.<ref name=polly/> Their eyes and ears tend to be the warmest regions.<ref name=polly/> It has been found that temperatures of lower appendages were no more than {{cvt|2.5|C-change}} above ambient temperature, which minimizes heat exchange between feet, toes, wings, and legs.<ref name=polly/>

Both the Gular and air sacs, being close to body temperature, are the main contributors to heat and water loss.<ref name=Schmidt-Nielsen/> Surface temperature can be affected by the rate of blood flow to a certain area and also by the surface area of the surrounding tissue.<ref name=zool241/> The ostrich reduces blood flow to the trachea to cool itself and [[Vasodilation|vasodilates]] to its blood vessels around the gular region to raise the temperature of the tissue.<ref name=Schmidt-Nielsen/> The air sacs are poorly vascularized but show an increased temperature, which aids in heat loss.<ref name=Schmidt-Nielsen/>

Common ostriches have evolved a 'selective brain cooling' mechanism as a means of thermoregulation. This modality allows the common ostrich to manage the temperature of the blood going to the brain in response to the extreme [[ambient temperature]] of the surroundings. The morphology for heat exchange occurs via [[cerebral arteries]] and the [[Ophthalmic artery|ophthalmic]] [[Blood vessel|rete]], a network of arteries originating from the [[ophthalmic artery]]. The [[Ophthalmic artery|ophthalmic]] [[Blood vessel|rete]] is [[analogous]] to the [[carotid rete]] found in mammals, as it also facilitates transfer of heat from arterial blood coming from the core to venous blood returning from the evaporative surfaces at the head.<ref name=Maloney/>

Researchers suggest that common ostriches also employ a 'selective brain warming' mechanism in response to cooler surrounding temperatures in the evenings. The brain was found to maintain a warmer temperature when compared to [[carotid]] [[arterial]] blood supply. Researchers hypothesize three mechanisms that could explain this finding:<ref name=Maloney/>
# They first suggest a possible increase in [[metabolic]] heat production within the brain tissue itself to compensate for the colder [[arterial]] blood arriving from the core.
# They also speculate that there is an overall decrease in cerebral blood flow to the brain.
# Finally, they suggest that warm venous blood [[perfusion]] at the [[Ophthalmic artery|ophthalmic]] [[Blood vessel|rete]] helps to warm the cerebral blood that supplies the [[hypothalamus]].
Further research will need to be done to find how this occurs.<ref name=Maloney/>

====Breathing adaptations====

The common ostrich has no [[sweat glands]], and under heat stress they rely on panting to reduce their body temperature.<ref name=Schmidt-Nielsen/> [[endotherm|Panting]] increases [[heat transfer|evaporative heat]] (and water) loss from its respiratory surfaces, therefore forcing air and heat removal without the loss of metabolic salts.<ref name=Mitchell /> Panting allows the common ostrich to have a very effective respiratory evaporative water loss (REWL). Heat dissipated by respiratory evaporation increases linearly with ambient temperature, matching the rate of heat production.<ref name=Deeming /> As a result of panting the common ostrich should eventually experience alkalosis.<ref name=zool241 /> However, The CO<sub>2</sub> concentration in the blood does not change when hot ambient temperatures are experienced.<ref name=Schmidt-Nielsen/> This effect is caused by a [[Shunt (medical)|lung surface shunt]].<ref name=Schmidt-Nielsen/> The lung is not completely shunted, allowing enough oxygen to fulfill the bird's [[Metabolism|metabolic]] needs.<ref name=Schmidt-Nielsen/> The common ostrich utilizes [[Gular fluttering#Endothermy|gular fluttering]], rapid rhythmic contraction and relaxation of throat muscles, in a similar way to panting.<ref name=zool241 /> Both these behaviors allow the ostrich to actively increase the rate of evaporative cooling.<ref name=zool241 />
 
In hot temperatures water is lost via respiration.<ref name=zool241 /> Moreover, varying surface temperatures within the respiratory tract contribute differently to overall heat and water loss through panting.<ref name=Schmidt-Nielsen/> The surface temperature of the [[Gular skin|gular area]] is {{cvt|38|C}}, that of the [[Vertebrate trachea|tracheal area]] is between {{cvt|34|and|36|C}}, and that of both anterior and posterior air sacs is {{cvt|38|C}}.<ref name=Schmidt-Nielsen/> The long trachea, being cooler than body temperature, is a site of water evaporation.<ref name=Schmidt-Nielsen/>
 
As ambient air becomes hotter, additional evaporation can take place lower in the trachea making its way to the posterior sacs, shunting the lung surface.<ref name=Schmidt-Nielsen/> The trachea acts as a buffer for evaporation because of the length and the controlled vascularization.<ref name=Schmidt-Nielsen /> The Gular is also heavily vascularized; its purpose is for cooling blood, but also evaporation, as previously stated. Air flowing through the trachea can be either [[Laminar flow|laminar]] or [[Turbulence|turbulent]] depending on the state of the bird.<ref name=zool241 /> When the common ostrich is breathing normally, under no heat stress, air flow is laminar.<ref name=Schmidt-Nielsen/> When the common ostrich is experiencing heat stress from the environment the air flow is considered turbulent.<ref name=Schmidt-Nielsen/> This suggests that laminar air flow causes little to no heat transfer, while under heat stress turbulent airflow can cause maximum heat transfer within the trachea.<ref name=Schmidt-Nielsen/>

====Metabolism====
Common ostriches are able to attain their necessary energetic requirements via the [[redox|oxidation]] of absorbed nutrients. Much of the metabolic rate in animals is dependent upon their [[allometry]], the relationship between body size to shape, anatomy, physiology, and behavior of an animal. Hence, it is plausible to state that metabolic rate in animals with larger masses is greater than animals with a smaller mass.

When a bird is inactive and unfed, and the [[Room temperature|ambient temperature]] (i.e. in the [[thermal neutral zone|thermo-neutral zone]]) is high, the energy expended is at its minimum. This level of expenditure is better known as the [[Basal metabolic rate|basal metabolic rate (BMR)]], and can be calculated by measuring the amount of oxygen consumed during various activities.<ref name=Deeming/> Therefore, in common ostriches we see use of more energy when compared to smaller birds in absolute terms, but less per unit mass.

A key point when looking at the common ostrich metabolism is to note that it is a [[passerine|non-passerine]] bird. Thus, BMR in ostriches is particularly low with a value of only 0.113 mL O<sub>2</sub> g<sup>−1</sup> h<sup>−1</sup>. This value can further be described using [[Kleiber's law]], which relates the BMR to the body mass of an animal.<ref name="Willmer_2009">{{cite book|last=Willmer|first=Pat|title=Environmental Physiology of Animals|year=2009|publisher=Wiley-Blackwell|isbn=978-1405107242|url=https://archive.org/details/environmentalphy00will}}</ref>

:Metabolic rate = 70''M''<sup>0.75</sup>

where ''M'' is body mass, and metabolic rate is measured in [[Calorie|kcal]] per day.

In common ostriches, a BMR (mL O<sub>2</sub> g<sup>−1</sup> h<sup>−1</sup>) = 389&nbsp;kg<sup>0.73</sup>, describing a line parallel to the intercept with only about 60% in relation to other non-passerine birds.<ref name= Deeming/>

Along with BMR, energy is also needed for a range of other activities. If the [[Room temperature|ambient temperature]] is lower than the [[thermal neutral zone|thermo-neutral zone]], heat is produced to maintain [[Thermoregulation|body temperature]].<ref name=Deeming/> So, the metabolic rate in a resting, unfed bird, that is producing heat is known as the [[Basal metabolic rate|standard metabolic rate (SMR)]] or [[Basal metabolic rate|resting metabolic rate (RMR)]]. The common ostrich SMR has been seen to be approximately 0.26 mL O<sub>2</sub> g<sup>−1</sup> h<sup>−1</sup>, almost 2.3 times the BMR.<ref name=Deeming/> On another note, animals that engage in extensive physical activity employ substantial amounts of energy for power. This is known as the maximum [[Allometry|metabolic scope]]. In an ostrich, it is seen to be at least 28 times greater than the BMR. Likewise, the daily energy [[Enzyme kinetics|turnover rate]] for an ostrich with access to free water is 12,700&nbsp;kJ&nbsp;d<sup>−1</sup>, equivalent to 0.26&nbsp;mL&nbsp;O<sub>2</sub>&nbsp;g<sup>−1</sup>&nbsp;h<sup>−1</sup>.<ref name=Deeming/>

==Status and conservation==
[[File:Nurmijärvi ostrich farm.jpg|thumb|The Ketola Ostrich Farm in [[Nurmijärvi]], [[Finland]]<ref>[https://agrocenter.fi/ Strutsitarha Ketolan Tila] (in Finnish)</ref><ref>{{cite web| url = https://www.theelephantmum.com/strawberry-season-has-started/| title = Strawberry season has started - The Elephant Mum| date = 19 July 2017}}</ref>]]
The wild common ostrich population has declined drastically in the last 200 years, with most surviving birds in reserves or on farms.<ref name="Davies"/> However, its range remains very large ({{cvt|9800000|km2|disp=or}}), leading the [[IUCN]] and [[BirdLife International]] to treat it as a species of [[least concern]].<ref name="iucn status 19 November 2021" /> Of its five subspecies, the [[Arabian ostrich]] (''S. c. syriacus'') became extinct around 1966. North African ostrich populations are protected under Appendix I of the [[Convention on International Trade in Endangered Species]] (CITES) meaning commercial international trade is prohibited and non-commercial trade is strictly regulated.<ref name="CITESAppendices"/>

[[File:Killing ostriches on the Zliten mosaic.JPG|thumb|Roman mosaic, 2nd century AD]]

==Humans==
Common ostriches have inspired cultures and civilizations for 5,000 years in [[Mesopotamia]] and African centres like [[Egypt]] and the [[Kingdom of Kush]]. A statue of [[Arsinoe II of Egypt]] riding a common ostrich was found in a tomb in Egypt.<ref name=Thompson/> [[Hunter-gatherer]]s in the [[Kalahari]] use ostrich eggshells as water containers, punching a hole in them. They also produce jewelry from it.<ref name="Davies"/><ref>Anderson, Richard L. (2004). ''Calliope's Sisters: A Comparative Study of Philosophies of Art.'' 2nd edition. Pearson.</ref><ref name=Laufer/> The presence of such eggshells with engraved hatched symbols dating from the [[Howiesons Poort]] period of the [[Middle Stone Age]] at [[Diepkloof Rock Shelter]] in South Africa suggests common ostriches were an important part of human life as early as 60,000 BP.<ref name="Texier"/>

[[File:Cyprus-lazarus-church-wall hg.jpg|thumb|Eggs on the oil lamps of the [[Church of Saint Lazarus, Larnaca]], Cyprus]]
In [[Eastern Christianity]] it is common to hang decorated common ostrich eggs on the chains holding the oil lamps.<ref name="CathDict"/> The initial reason was probably to prevent mice and rats from climbing down the chain to eat the oil.<ref name="CathDict"/> Another, symbolical explanation is based in the [[Ostrich#Mating|fictitious]] tradition that female common ostriches do not sit on their eggs, but stare at them incessantly until they hatch out, because if they stop staring even for a second the egg will addle.<ref name="CathDict"/> This is equated to the obligation of the Christian to direct his entire attention towards God during prayer, lest the prayer be fruitless.<ref name="CathDict">{{cite book |article= Ostrich Eggs |title= A Catholic Dictionary |edition = 3rd |editor= Attwater, Donald |year=1997 |location= Charlotte, North Carolina |publisher= TAN Books |isbn=978-0-89555-549-6 |url= https://books.google.com/books?id=8GrGCwAAQBAJ&pg=PT688}}</ref>

{{anchor|Myth}}

==="Head in the sand" misconception===
[[List of common misconceptions|Contrary to popular assumptions]], ostriches do not bury their heads in sand to avoid danger.<ref name=Gosselin/> This misconception likely began with [[Pliny the Elder]] (23–79&nbsp;CE), who wrote that ostriches "imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed."<ref name=Kruszelnicki/> This may have been a misunderstanding of their sticking their heads in the sand to swallow sand and pebbles to help digest their fibrous food,<ref name=Kreibich/> or, as [[National Geographic Society|National Geographic]] suggests, of the defensive behavior of lying low, so that they may appear from a distance to have their head buried.<ref name=NationalGeog/> Another possible origin for the assumption lies with the fact that ostriches keep their eggs in holes in the sand instead of nests and must rotate them using their beaks during incubation; digging the hole, placing the eggs, and rotating them might each be mistaken for an attempt to bury their heads in the sand.<ref name="ScienceWorldHeadSand">{{cite web|title=Do ostriches really bury their heads in the sand?|url=https://www.scienceworld.ca/blog/do-ostriches-really-bury-their-heads-sand|website=Science World British Columbia|access-date=2 January 2017|date=11 December 2015}}</ref>

===Economic use===
[[File:Ostrich feathers 1919.jpg|thumb|left|Fashion accessories, Amsterdam, 1919|alt=Fashion accessories made from feathers, Amsterdam, 1919]]
[[File:1000 Ostriches on the move.ogv|thumb|Being moved between camps in preparation for filming a movie in South Africa]]
In [[Roman Empire|Roman]] times, there was a demand for common ostriches to use in ''[[venatio]]'' games or cooking. They have been hunted and farmed for their feathers, which at various times have been popular for ornamentation in fashionable clothing (such as hats during the 19th century). Their skins are valued for their [[Ostrich leather|leather]]. In the 18th century they were almost hunted to extinction; farming for feathers began in the 19th century. At the start of the 20th century there were over 700,000 birds in captivity.<ref name=Perrins/> The market for feathers collapsed after [[World War I]], but commercial farming for feathers and later for skins and meat became widespread during the 1970s. 
[[File:Ostrich in captivity.jpg|thumb|An ostrich in captivity in a farm park in [[Gloucestershire]], England.]]
[[File:Ostrich Platter.jpg|thumb|A platter of ostrich meat in Oudtshoorn, South Africa]]
Common ostriches have been farmed in South Africa since the beginning of the 19th century. According to [[Frank G. Carpenter]], the English are credited with first [[Tame animal|taming]] common ostriches outside [[Cape Town]]. Farmers captured baby common ostriches and raised them successfully on their property, and they were able to obtain a crop of feathers every seven to eight months instead of killing wild common ostriches for their feathers.<ref name="WDL">{{cite web |url = http://www.wdl.org/en/item/566/ |title = Africa—Cape of Good Hope, Ostrich Farm |work = [[World Digital Library]] |date = 1910–1920 |access-date = 30 May 2013 }}</ref> Feathers are still commercially harvested.<ref>{{cite news |last= Bryce|first=Emma  |date= 20 February 2023|title=Festivals, fashion and feather bandits: why ostrich plumage is still worth its weight in gold – a photo essay |url=https://www.theguardian.com/environment/2023/feb/20/ostrich-feathers-farming-south-africa-fashion-luxury-a-photo-essay |work=the Guardian |location= |access-date=23 November 2023}}</ref> It is claimed that common ostriches produce the strongest commercial leather.<ref name=Best/> Common ostrich meat tastes similar to lean beef and is low in fat and [[cholesterol]], as well as high in [[calcium]], protein, and iron. It is considered to be both poultry and [[red meat]].<ref>{{cite web |url=https://ask.usda.gov/s/article/Are-ratites-red-or-white-meat |title=Are ratites "red" or "white" meat? |website=AskUSDA |publisher=US Department of Agriculture |date=17 Jul 2019 |access-date=15 November 2022 |archive-date=15 November 2022 |archive-url=https://web.archive.org/web/20221115100641/https://ask.usda.gov/s/article/Are-ratites-red-or-white-meat |url-status=dead }}</ref> Uncooked, it is dark red or cherry red, a little darker than beef.<ref name=COA/> [[Ostrich stew]] is a dish prepared using common ostrich meat.

Some common ostrich farms also cater to [[agri-tourism]], which may produce a substantial portion of the farm's income.<ref>{{cite news|title=Agritourism helps ostrich farm fly high|newspaper=Farmer's Weekly|date= 19 March 2007}}</ref> This may include tours of the farmlands, souvenirs, or even ostrich rides.<ref>{{cite web|url=http://curacaoostrichfarm.com/?lang=en|title=Curacao Ostrich Farm}}</ref><ref>{{cite web|title=South Africa Ostrich Rides|url=http://www.sa-venues.com/activities/ostrich-rides.htm}}</ref>

===Attacks===
Common ostriches typically avoid humans in the wild, since they correctly assess humans as potential predators. If approached, they often run away, but sometimes ostriches can be very aggressive when threatened, especially if cornered, and may also attack if they feel the need to defend their territories or offspring. Similar behaviors are noted in captive or domesticated common ostriches, which retain the same natural instincts and can occasionally respond aggressively to stress. When attacking a person, common ostriches deliver slashing kicks with their powerful feet, armed with long claws, with which they can [[Disembowelment|disembowel]] or kill a person with a single blow.<ref>{{cite book|author=Coyne, Jerry A. |title=Why Evolution Is True |url=https://books.google.com/books?id=XK31XqoKJKoC&pg=PT76 |year=2010 |publisher=Penguin |isbn=978-0-14-311664-6 |pages=76–}}</ref> In one study of common ostrich attacks, it was estimated that two to three attacks that result in serious injury or death occur each year in the area of [[Oudtshoorn]], South Africa, where a large number of common ostrich farms are set next to both feral and wild common ostrich populations, making them statistically, the world's most dangerous bird.<ref name="Wood"/><ref name = "OstrichTrauma"/>

===Racing===

{{See also|List of racing forms#Animal racing}}
[[File:OstrichCartJacksonville1.jpg|thumb|right|upright|[[Jacksonville, Florida]], circa 1911|alt=Ostrich-drawn cart carrying a man, circa 1911, [[Jacksonville, Florida]]]]

In some countries, people [[racing|race each other]] on the backs of common ostriches. The practice is common in Africa<ref name="jhbradley"/> and is relatively unusual elsewhere.<ref name=park/> The common ostriches are ridden in the same way as horses with special saddles, reins, and bits. However, they are harder to manage than horses.<ref name=mech/> The practice is becoming less common due to ethical concerns, and nowadays ostrich farms set a limit weight for people to ride ostriches, making the activity mostly suited for children and smaller adults.<ref>{{cite web |title=Ostrich Riding & Racing – The Bizzarre Sport You Never Heard of |url=https://sand-boarding.com/ostrich-riding/ |website=Sand-boarding.com |date=30 December 2021 |access-date=28 April 2022}}</ref>
[[File:Struisvogelrennen-514008.ogv|thumb|left|upright|1933, The Netherlands|alt=Racing, 1933, The Netherlands]]
The racing is also a part of modern [[South African culture]].<ref name=Pyke/> Within the United States, a [[tourist attraction]] in [[Jacksonville, Florida]], called 'The Ostrich Farm' opened up in 1892; it and its races became one of the most famous early [[tourist attraction|attractions]] in the [[history of Florida]].<ref name=Clark/> Likewise, the arts scene in [[Indio, California]], consists of both ostrich and [[camel racing]].<ref name="Barton 2013">{{cite web|first1=Dave|last1=Barton|url=http://www.ocweekly.com/arts/florian-ayala-fauna-art-magickian-6425518|title=Florian-Ayala Fauna: Art Magickian|work=[[OC Weekly]]|publisher=OC Weekly, LP.|date=7 February 2013|access-date=17 August 2016|archive-url=https://web.archive.org/web/20161006210659/http://www.ocweekly.com/arts/florian-ayala-fauna-art-magickian-6425518|archive-date=6 October 2016|url-status=dead}}</ref>
[[Chandler, Arizona]], hosts the annual "[[Ostrich Festival]]", which features common ostrich races.<ref name=Scott/><ref name=Hedding/> Racing has also occurred at many other locations such as [[Virginia City]] in [[Nevada]], [[Canterbury Park]] in [[Minnesota]],<ref name=midwest/> [[Prairie Meadows]] in [[Iowa]], [[Ellis Park Racecourse|Ellis Park]] in [[Kentucky]],<ref name=Ethridge/> and the [[Fair Grounds Race Course|Fairgrounds]] in [[New Orleans]], Louisiana.<ref>DeMocker, Michael (August 2014) [http://www.nola.com/horseracing/index.ssf/2014/08/exotic_animal_racing_at_the_fa.html "Exotic animal racing at the Fair Grounds Race Course: photo gallery"]. nola.com</ref><ref>{{cite web |title=Ostrich Races in the US |url=https://sand-boarding.com/ostrich-races/ |website=Sand-boarding.com |date=31 August 2021 |access-date=23 April 2022}}</ref>

== See also ==

* [[Tallest extant birds]]
{{Clear}}

==Notes==
{{NoteFoot}}

==References==
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<ref name=BBC>{{cite news| url=http://news.bbc.co.uk/1/hi/scotland/2834025.stm | title=Ostriches "Flirt With Farmers" | work=BBC News | date=9 March 2003}}</ref>

<ref name=Bertram1979>{{cite journal|last=Bertram|first=B.C.R.|title=Ostriches recognise their own eggs and discard others|journal=Nature|year=1979|volume=279|pages=233–234|issue=5710|pmid=440431|doi=10.1038/279233a0|bibcode=1979Natur.279..233B|s2cid=4236729}}</ref>

<ref name="Bertram 1992">Bertram, Brian C.R. (1992). ''[https://books.google.com/books?id=xaNiQgAACAAJ The Ostrich Communal Nesting System]''. Princeton University Press.{{page needed|date=November 2013}}</ref>

<ref name=Best>{{cite web | title=Genuine Ostrich Leather | last=Lappin | first=Alan | year=2017 | publisher=Roden Leather Company | url=https://www.rodenleather.com/single-post/2017/06/26/Genuine-Ostrich-Leather | access-date=25 April 2020 | archive-date=10 August 2020 | archive-url=https://web.archive.org/web/20200810160604/https://www.rodenleather.com/single-post/2017/06/26/Genuine-Ostrich-Leather | url-status=dead }}</ref>

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<ref name=COA>{{cite web| url=http://www.ostrich.ca/cooking/index.htm | title=Cooking Tips| author=Canadian Ostrich Association |date=April 2008| archive-url=https://web.archive.org/web/20110706192632/http://www.ostrich.ca/cooking/index.htm| archive-date=6 July 2011| url-status=dead}}</ref>

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<ref name=Hedding>{{cite web|publisher=[[About.com]]|url=http://phoenix.about.com/od/arizonapicturesandphotos/ig/Ostrich-Festival/Ostrich-Festival-17.htm|last=Hedding|first=Judy|year=2008|access-date=30 July 2009|title=Ostrich Festival|archive-url=https://web.archive.org/web/20090915193649/http://phoenix.about.com/od/arizonapicturesandphotos/ig/Ostrich-Festival/Ostrich-Festival-17.htm|archive-date=15 September 2009|url-status=dead}}</ref>

<ref name=Hiskey>{{cite web|url=http://www.todayifoundout.com/index.php/2010/08/ostriches-dont-hide-their-heads-in-the-sand/ |last=Hiskey|first=Daven|title=Ostriches Don't Hide Their Heads in the Sand |publisher=Todayifoundout.com |date=12 August 2010 |access-date=7 November 2012}}</ref>

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<ref name=King>{{cite book |last1=King |first1=J. R. |last2=Farner |first2=D.S. |chapter=Energy Metabolism, thermoregulation, and body temperature |title=Biology and Comparative Physiology of Birds |year=1961 |volume=2 |pages=215–88 |editor1-first=A. J. |editor1-last=Marshall |publisher=Academic Press |location=New York |doi=10.1016/B978-1-4832-3143-3.50014-9 |isbn=978-1-4832-3143-3}}</ref>

<ref name=Kreibich>{{cite book|last1=Kreibich|first1=Andreas|last2=Sommer|first2=Mathias|title=Ostrich Farm Management|date=1995|publisher=Landwirtschaftsverlag GmbH|isbn=978-3784327297}} cited in {{cite book|last1=Ekesbo|first1=Ingvar|title=Farm Animal Behaviour: Characteristics for Assessment of Health and Welfare|date=2011|publisher=CABI|isbn=9781845937706|page=181|url=https://books.google.com/books?id=vFX8fJp6pmoC&pg=PA181}}</ref>

<ref name=Kruszelnicki>{{cite web| url=http://www.abc.net.au/science/articles/2006/11/02/1777947.htm | title=Ostrich head in sand | date=2 November 2006 | last=Kruszelnicki | first=Karl | work=ABC Science: In Depth | publisher=[[Australian Broadcasting Corporation]]}}</ref>

<ref name=Laufer>{{Cite journal|last1=Laufer|first1=B. |year=1926 |title=Ostrich Eggshell Cups of Mesopotamia and the Ostrich in Ancient and Modern Times |journal=Anthropology Leaflet |volume=23 |url=https://archive.org/details/ostricheggshellc24lauf }}</ref>

<ref name=Linnaeus>{{cite book |last1=Linnaeus|first1=Carolus |author-link1=Carl Linnaeus |title=Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata |year=1758 |language=la |page=155 }} <!-- Holmiae. (Laurentii Salvii)., . "S. pedibus didactylis" Preceding was left off when converted to template form. Please add if you know Latin and/or where it belongs --></ref>

<ref name=Maina>{{cite journal|last=Maina|first=J.N.|author2=Nathaniel C.|title=A qualitative and quantitative study of the lung of an ostrich, ''Struthio camelus''|journal=The Journal of Experimental Biology|year=2001|volume=204|pages=2313–2330|pmid=11507114|issue=Pt 13|doi=10.1242/jeb.204.13.2313|url=http://jeb.biologists.org/cgi/content/short/204/13/2313|url-access=subscription}}</ref>

<ref name=Maclean>{{cite book |last1=Maclean|first1=Gordon Lindsay|title=The Ecophysiology of Desert Birds |url=https://books.google.com/books?id=YvmC2sU-LqgC |publisher=Springer-Verlag |location=Berlin |isbn=978-3-540-59269-3 |page=26 |year=1996 }}</ref><ref name=Maloney>{{cite journal|last1=Maloney|first1=Shane K|title=Termoregulation in ratities:a review|journal=Australian Journal of Experimental Agriculture|volume=48|pages=1293–1301|doi=10.1071/EA08142|year=2008|issue=10}}</ref>

<ref name=Marshall>{{cite book |last1=Marshall|first1=Alan John |title=Biology and Comparative Physiology of Birds |url=https://books.google.com/books?id=fsE9AAAAIAAJ|year=1960 |publisher=Academic Press |page=446|isbn=9780124736016 }}</ref>

<ref name=Martin2000>{{Cite journal|last1=Martin |first1=G. R. | last2=Katzir|first2=G. |year=2000 |title=Sun Shades and Eye Size in Birds |journal=Brain, Behavior and Evolution |volume=56 |issue=6 |pages=340–344 |doi= 10.1159/000047218 |pmid=11326139 |s2cid=43023723 }}</ref>

<ref name=Martin2001>{{Cite journal|last1=Martin| first1=G. R. | last2=Ashash|first2=U. |last3=Katzir|year=2001|title=Ostrich ocular optics |journal=Brain, Behavior and Evolution |volume=58|issue=2|pages=115–120 |doi= 10.1159/000047265 | pmid=11805377 |first3=Gadi| s2cid=46827656 }}</ref>

<ref name=mech>{{cite web|publisher=[[Mechanix Illustrated]]|title='They're Off!' Thrills of the Turf in Ostrich Racing|date=September 1929|author=Modern Mechanix|access-date=17 March 2017|url=http://blog.modernmechanix.com/mags/ModernMechanix/9-1929/ostrich_races.jpg|archive-date=28 January 2016|archive-url=https://web.archive.org/web/20160128215242/http://blog.modernmechanix.com/mags/ModernMechanix/9-1929/ostrich_races.jpg|url-status=dead}}</ref>

<ref name=NationalGeog>{{cite web| url=http://animals.nationalgeographic.com/animals/birds/ostrich/ | archive-url=https://web.archive.org/web/20100207174412/http://animals.nationalgeographic.com/animals/birds/ostrich/ | url-status=dead | archive-date=7 February 2010 | title=Ostrich Struthio camelus |author=National Geographic Society |year=2009}}</ref>

<ref name="Nell 2003">{{cite book |last1=Nell |first1=Leon |title=The Garden Route and Little Karoo |url=https://books.google.com/books?id=Sjatn8zolvsC&pg=PA164 |year=2003 |publisher=Struik Publishers |location=Cape Town |isbn=978-1-86872-856-5 |page=164 }}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

<ref name=park>{{cite news|title=Extreme Race Day at Canterbury Park|newspaper=[[City Pages]]|first=Ben |last=Palosaari |date=19 July 2008|url=http://blogs.citypages.com/sports/2008/07/extreme_race_da.php |archive-url=https://web.archive.org/web/20150318151733/http://blogs.citypages.com/sports/2008/07/extreme_race_da.php |archive-date=18 March 2015}}</ref>

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<ref name=Pyke>{{Cite book|title=Weird and Wonderful Science Facts|first=Magnus|last=Pyke|year=1985|page=[https://archive.org/details/weirdwonderfulsc0000pyke/page/82 82]|isbn=978-0-8069-6254-2|publisher=Sterling Pub Co. Inc.|url=https://archive.org/details/weirdwonderfulsc0000pyke/page/82}}</ref>

<ref name="Roots 2006">{{cite book |last1=Roots|first1=Clive |url=https://books.google.com/books?id=Sb1IJYzXZhUC|title=Flightless Birds|publisher=Greenwood Press |location=Westport, CT |isbn=978-0-313-33545-7 |page=26 |year=2006}}</ref>

<ref name=Schmidt-Nielsen>{{cite journal|last=Schmidt-Nielsen|first=K.|author2=Kanwish, J. Lawsiewski R. C.|title=Temperature Regulation and Respiration in the Ostrich|journal=The Condor|year=1969|volume=71|pages=341–352|doi=10.2307/1365733|issue=4|url=https://sora.unm.edu/sites/default/files/journals/condor/v071n04/p0341-p0352.pdf|jstor=1365733}}</ref>

<ref name=Scott>{{cite web| url=http://www.azcentral.com/community/chandler/articles/2011/03/08/20110308chandler-ostrich-festival0308.html | title=Shake a tail feather, get out to Ostrich Festival |  last=Scott | first=Luci | date=8 March 2011 | work=AZCentral.com | publisher=The Arizona Republic}}</ref>

<ref name=coprodeum>{{cite journal |last1=Skadhauge|first1=E. | last2=Erlwanger|first2= K. H. |last3=Ruziwa|first3=S. D. | last4=Dantzer|first4=V. |last5=Elbrønd |first5=V. S. | last6=Chamunorwa |first6=J. P. |year=2003 |title=Does the ostrich (''Struthio camelus'') have the electrophysiological properties and microstructure of other birds? |journal=Comparative Biochemistry and Physiology A |volume=134 |issue=4 |pages=749–755 |pmid= 12814783|doi= 10.1016/S1095-6433(03)00006-0}}</ref>

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| last2 = Horbańczuk | first2 = J. O. 
| last3 = Villegas-Vizcaíno | first3 = R. 
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| last5 = Faki Mohammed | first5 = A. E. 
| last6 = Mahrose | first6 = K. M. A. 
| doi = 10.1007/s11250-009-9428-2 
| title = Wild ostrich (''Struthio camelus'') ecology and physiology 
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| volume = 42 
| issue = 3 
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| year = 2009 
| pmid = 19693684 
| s2cid = 22907744 
}}</ref>
}}

==Further reading==
{{Portal|Animals|Birds|Africa}}
* {{cite book |last1=Cooper|first1=J. C. |title=Symbolic and Mythological Animals |year=1992 |publisher=Harpercollins |location=New York, NY |isbn=978-1-85538-118-6 |pages=170–171}}
* {{cite encyclopedia |last=Folch |first= A. |editor1-last=del Hoya|editor1-first=Josep|editor2-last=Sargatal|editor2-first=Jordi|encyclopedia=Handbook of the Birds of the World |title=Family Struthionidae (Ostrich) |year=1992 |publisher=Lynx Edicions|location=Barcelona |volume=1, Ostrich to Ducks |isbn=978-84-87334-09-2 |pages=76–83 }}
* {{cite encyclopedia |editor1-first=Michael Vincent |editor1-last=O'Shea |editor2-first=Ellsworth D. |editor2-last=Foster |editor3-first=George Herbert |editor3-last=Locke |title=Ostrich |url=https://books.google.com/books?id=bHNs2i9IYDMC&pg=PA4423|year=1918 |publisher=The World Book, Inc. | location=Chicago, IL|volume=6 |pages=4422–4424 }}

==External links==
{{Wikiquote|Ostriches}}
{{Wiktionary|Ostrich}}
{{Commons and category|Struthio camelus|Struthio camelus}}
*{{Wikisource-inline|Littell's Living Age/Volume 134/Issue 1732/Capturing Ostriches|a description of traditional methods used by Arabs to capture wild ostriches.}}
* (Common) Ostrich – [http://sabap2.adu.org.za/docs/sabap1/001.pdf Species text in The Atlas of Southern African Birds].
* [http://www.ostrich.org.uk/ British Domesticated Ostrich Association]
* [https://web.archive.org/web/20070206010309/http://www.blue-mountain.net/research.htm Index for various ostrich studies and papers]
* {{usurped|1=[https://web.archive.org/web/20040414065338/http://www.world-ostrich.org/ World Ostrich Association]}}

{{Taxonbar|from=Q17592}}
{{Authority control}}

[[Category:Struthio|common ostrich]]
[[Category:Domesticated birds]]
[[Category:Flightless birds]]
[[Category:Livestock]]
[[Category:Ratites]]
[[Category:Birds of Africa]]
[[Category:Birds of Sub-Saharan Africa]]
[[Category:Extant Miocene first appearances]]
[[Category:Birds described in 1758|common ostrich]]
[[Category:Articles containing video clips]]
[[Category:Taxa named by Carl Linnaeus|common ostrich]]
[[Category:Ostriches]]
[[Category:Invasive animal species in Australia]]