View source for Reindeer

{{Short description|Species of deer}}
{{Other uses}}
{{Redirect|Caribou}}
{{pp-extended|small=yes}}
{{Use dmy dates|date=January 2019}}
{{Speciesbox
| name = Reindeer<br />(Caribou)
| fossil_range = {{fossil range|.62|0|refs=<ref name="Kurt">{{Cite book |first=Björn|last=Kurtén|year=1968|title=Pleistocene Mammals of Europe|pages=170–177 |url=https://books.google.com/books?id=OsPBXSNL8ZkC&pg=PA170|access-date=6 August 2013 |isbn=978-1-4128-4514-4 |publisher=[[Transaction Publishers]]}}</ref>|[[Chibanian]] to present}}
| image = Reinbukken på frisk grønt beite. - panoramio.jpg
| image_caption = A reindeer in Norway
| status = VU
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Gunn, A. |date=2016 |title=''Rangifer tarandus'' |volume=2016 |page=e.T29742A22167140 |doi=10.2305/IUCN.UK.2016-1.RLTS.T29742A22167140.en |access-date=19 November 2021}}</ref>
| status2 = G5
| status2_system = TNC
| status2_ref = <ref>{{cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.103369/Rangifer_tarandus |website=explorer.natureserve.org |access-date=30 March 2022}}</ref>
| parent_authority = [[Charles Hamilton Smith|C. H. Smith]], 1827
| authority = ([[Carl Linnaeus|Linnaeus]], 1758)
| display_parents = 2
| taxon = Rangifer tarandus
| subdivision_ranks = Species
| subdivision = [[#Species and subspecies|See text]], traditionally 1, but possibly up to 6
| range_map = Rangifer tarandus map.png
| range_map_caption = Reindeer range: North American (green), Eurasian (red), and [[Alaska Reindeer Service|Alaskan introduced]] (orange)
}}

The '''reindeer''' or '''caribou'''{{efn|In [[North American English]], known as '''caribou''' if wild and '''reindeer''' if domesticated<ref>{{cite web | url=https://www.fda.gov/animal-veterinary/animal-health-literacy/fun-facts-about-reindeer-and-caribou | title=Fun Facts about Reindeer and Caribou | author=[[United States Food and Drug Administration]] (FDA) | website=[[Food and Drug Administration]] | date=13 December 2022 }}</ref>}} ('''''Rangifer tarandus''''')<ref name=Flagstad/> is a species of [[deer]] with [[circumpolar distribution]], native to [[Arctic]], [[subarctic]], [[tundra]], [[taiga|boreal]], and mountainous regions of Northern Europe, Siberia, and North America.<ref name="iucn status 19 November 2021" /> It is the only representative of the genus '''''Rangifer'''''. More recent studies suggest the splitting of reindeer and caribou into six distinct species over their range.

Reindeer occur in both [[Animal migration|migratory]] and [[wiktionary:sedentary#Adjective|sedentary]] populations, and their herd sizes vary greatly in different regions. The tundra subspecies are adapted for extreme cold, and some are adapted for long-distance migration.

Reindeer vary greatly in size and color from the smallest, the [[Svalbard reindeer]] (''R.'' (''t.'') ''platyrhynchus''), to the largest, Osborn's caribou (''R. t. osborni''). Although reindeer are quite numerous, some species and subspecies are in decline and considered [[Vulnerable species|vulnerable]]. They are unique among deer (Cervidae) in that females may have [[antler]]s, although the prevalence of antlered females varies by subspecies.

Reindeer are the only successfully semi-domesticated deer on a large scale in the world. Both wild and domestic reindeer have been an important source of food, clothing, and shelter for [[Circumpolar peoples|Arctic people]] from prehistorical times.  They are still herded and hunted today.<ref name="Burch" /> In some traditional [[Christmas]] legends, [[Santa Claus's reindeer]] pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve.

== Description ==
Names follow international convention<ref name="MSW3">{{MSW3 Grubb|id=14200328}}</ref><ref name="HBW">Mattioli, S. (2011). "Caribou (''Rangifer tarandus'')", pp. 431–432 in: ''Handbook of the Mammals of the World Vol. 2: Hoofed Mammals''. Lynx Edicions, Barcelona. {{ISBN|978-84-96553-77-4}}</ref> before the recent revision<ref name="Harding-2022">{{Cite journal |last=Harding |first=Lee E. |date=2022-08-26 |title=Available names for ''Rangifer'' (Mammalia, Artiodactyla, Cervidae) species and subspecies |journal=ZooKeys |issue=1119 |pages=117–151 |doi=10.3897/zookeys.1119.80233 |pmid=36762356 |pmc=9848878 |bibcode=2022ZooK.1119..117H |issn=1313-2970 |doi-access=free}}</ref> (see [[Reindeer#Taxonomy]] below). Reindeer / caribou (''Rangifer'') vary in size from the smallest, the [[Svalbard reindeer]] (''R.'' (''t.'') ''platyrhynchus''), to the largest, Osborn's caribou (''R. t. osborni''). They also vary in coat color and antler architecture.

The North American range of caribou extends from Alaska through the [[Yukon]], the [[Northwest Territories]] and [[Nunavut]] throughout the [[tundra]], [[taiga]] (boreal forest) and south through the Canadian [[Rocky Mountains]].<ref name="Eder2011">{{cite book |last1=Eder |first1=Tamara |last2=Kennedy |first2=Gregory |title=Mammals of Canada|year=2011 |page=[https://archive.org/details/mammalsofcanada0000eder/page/81 81] |publisher=Lone Pine |location=Edmonton, Alberta |url=https://archive.org/details/mammalsofcanada0000eder |isbn=978-1-55105-857-3}}</ref> Of the eight subspecies classified by Harding (2022) into the Arctic caribou (''R. arcticus''), the migratory mainland [[barren-ground caribou]] of [[Arctic Alaska]] and [[Northern Canada]] (''R. t. arcticus''), summer in tundra and winter in taiga, a transitional forest zone between boreal forest and tundra; the nomadic [[Peary caribou]] (''R. t. pearyi'') lives in the [[polar desert]] of the high [[Arctic Archipelago]] and Grant's caribou (''R. t. granti'' also called the [[Porcupine caribou]]) lives in the western end of the [[Alaska Peninsula]] and the adjacent islands; the other four subspecies, Osborn's caribou (''R. t. osborni''), Stone's caribou (''R. t. stonei''), the Rocky Mountain caribou (''R. t. fortidens'') and the Selkirk Mountains caribou (''R. t. montanus'') are all [[wiktionary:montane|montane]]. The extinct insular [[Queen Charlotte Islands caribou]] (''R. t. dawsoni''), lived on [[Graham Island]] in [[Haida Gwaii]] (formerly known as the Queen Charlotte Islands).

The [[boreal woodland caribou]] (''R. t. caribou''), lives in the boreal forest of northeastern Canada: the Labrador or Ungava caribou of [[northern Quebec]] and northern [[Labrador]] (''R. t. caboti''), and the Newfoundland caribou of [[Newfoundland and Labrador|Newfoundland]] (''R. t. terranovae'') have been found to be genetically in the woodland caribou lineage.<ref name="Cronin-2003" /><ref name="Yannic-2013" />

In Eurasia, both wild and domestic reindeer are distributed across the tundra and into the taiga. Eurasian [[mountain reindeer]] (''R. t. tarandus'') are close to North American caribou genetically and visually, but with sufficient differences to warrant division into two species. The unique, insular Svalbard reindeer inhabits the [[Svalbard|Svalbard Archipelago]]. The [[Finnish forest reindeer]] (''R. t. fennicus'') is spottily distributed in the coniferous forest zones from Finland to east of [[Lake Baikal]]: the Siberian forest reindeer (''R. t. valentinae'', formerly called the Busk Mountains reindeer (''R. t. buskensis'') by American taxonomists) occupies the [[Altai Mountains|Altai]] and [[Ural Mountains]].

Male ("bull") and female ("cow") reindeer can grow antlers annually, although the proportion of females that grow antlers varies greatly between populations.<ref name="MSW3" /> Antlers are typically larger on males. Antler architecture varies by species and subspecies and, together with pelage differences, can often be used to distinguish between species and subspecies (see illustrations in Geist, 1991<ref>{{Cite conference |last=Geist |first=Valerius |chapter=On an objective definition of subspecies, taxa as legal entities, and its application to ''Rangifer tarandus'' Lin. 1758 |editor1=C. E. Butler |editor2=S. P. Mahoney |title=Proceedings 4th North American Caribou Workshop, 1989 |year=1991 |location=St. John’s, Newfoundland |pages=1–76}}</ref> and Geist, 1998).<ref name="Geist1998">{{cite book |last=Geist |first=Valerius |year=1998|title=Deer of the world: their evolution, behavior, and ecology |location=Mechanicsburg, PA |publisher=Stackpole Books|url=https://books.google.com/books?id=bcWZX-IMEVkC|isbn=9780811704960}}</ref>

== Status ==
About 25,000 mountain reindeer (''R. t. tarandus'') still live in the mountains of Norway, notably in [[Hardangervidda]].<ref>{{Cite web |title=The wild reindeer areas in Norway |url=https://www.villrein.no/the-wild-reindeer-areas-in-norway |access-date=2022-11-14 |website=Villrein.no - alt om villrein |language=no-NO}}</ref> In Sweden there are approximately 250,000 reindeer in herds managed by [[Sámi peoples|Sámi]] villages.<ref>{{Cite web |title=Sami reindeer herding in Sweden |url=https://www.sametinget.se/rennaring_sverige |access-date=2023-11-08 |language=sv-SE}}</ref> [[Reindeer in Russia|Russia manages]] 19 herds of Siberian tundra reindeer (''R. t. sibiricus'') that total about 940,000.<ref name="Mizin-2018b">Mizin, I.A. (2018) The current state of the wild reindeer in Russia - general overview of the situation. Barents office of WWF Russia Russian Arctic National Park for World Wildlife Fund, Arkhangelsk, Russia, 8 pp.</ref> The [[Reindeer in Russia#Taimyr reindeer herd|Taimyr herd]] of Siberian tundra reindeer is the largest wild reindeer herd in the world,<ref name="NOAA2013">{{cite book |chapter=Migratory Tundra ''Rangifer'' |first1=D.E. |last1=Russell |first2=A. |last2=Gunn |pages=96–101 |publisher=NOAA Arctic Research Program |url=https://arctic.noaa.gov/Portals/7/ArcticReportCard/Documents/ArcticReportCard_full_report2013.pdf?ver=2019-06-14-143309-477 |editor-last1=Jeffries |editor-first1=M. O. |editor-last2=Richter-Menge |editor-first2=J. A. |editor-last3=Overland |editor-first3=J. E. |date=20 November 2013 |title=Arctic Report Card 2013 |access-date=16 November 2022 |archive-date=26 October 2022 |archive-url=https://web.archive.org/web/20221026160441/https://arctic.noaa.gov/Portals/7/ArcticReportCard/Documents/ArcticReportCard_full_report2013.pdf?ver=2019-06-14-143309-477 |url-status=dead }}</ref><ref name="Kolpashikov">{{Cite journal |doi=10.5751/ES-07129-200109| title=The role of harvest, predators, and socio-political environment in the dynamics of the Taimyr wild reindeer herd with some lessons for North America| journal=Ecology and Society| volume=20| year=2015| last1=Kolpasсhikov| first1=L.| last2=Makhailov| first2=V.| last3=Russell| first3=D. E.| doi-access=free| url=http://dlc.dlib.indiana.edu/dlc/bitstream/handle/10535/9749/ES-2014-7129.pdf?sequence=1&isAllowed=y|issn = 1708-3087 }}</ref> varying between 400,000 and 1,000,000; it is a metapopulation consisting of several subpopulations — some of which are phenotypically different<ref>{{cite journal |author=Shapkin, A. |date=2017 |title=About phenotypic variability of taimyr tundra wild reindeer (''Rangifer tarandus'') |language=ru, en |journal=Genetika i razvedenie životnyh |trans-journal=[[Genetics and Breeding of Animals]] |volume=1 |pages=22–30}}</ref> — with different migration routes and calving areas.<ref>{{cite journal |author1=Kholodova, M.V. |author2=Kolpashchikov, L.A. |author3=Kuznetsova, M.V. |author4=Baranova, A.I. |date=2011 |title=Genetic diversity of wild reindeer (''Rangifer tarandus'') of Taimyr: analysis of polymorphism of the control region of mitochondrial DNA |journal=[[Biology Bulletin]] |volume=38 |issue=1 |pages=42–49|doi=10.1134/S1062359011010067 |bibcode=2011BioBu..38...42K |s2cid=9180267 }}</ref><ref>{{cite journal |author=Krivoshapkin, A.A. |date=2016 |title=Миграция диких северных оленей (''Rangifer tarandus'' L.) таймырской популяции на территорию северо-западной Якутии |trans-title=Migration of wild reindeer (''Rangifer tarandus'' L.) of the Taimyr population to the territory of northwestern Yakutia |journal=ВЕСТНИК СВФУ |trans-journal=[[SVFU Bulletin]] Биологические науки [Biological Sciences] |volume=6 |pages=15–20}}</ref> The Kamchatkan reindeer (''R. t. phylarchus''), a forest subspecies, formerly included reindeer west of the [[Sea of Okhotsk]] which, however, are indistinguishable genetically from the Jano-Indigirka, [[East Siberian taiga]] and [[Chukchi Peninsula|Chukotka]] populations of ''R. t. sibiricus''.<ref name="Rozhkov-2020">{{Cite journal |last1=Rozhkov |first1=Yu.I. |last2=Davydov |first2=A.V. |last3=Morgunov |first3=N.A. |last4=Osipov |first4=K.I. |last5=Novikov |first5=B.V. |last6=Mayorov |first6=A.I. |last7=Tinaev |first7=N.I. |last8=Chekalova |first8=T.M. |last9=Yakimov |first9=O.A. |date=2020 |title=Генетическая Дифференциация Северного Оленя ''Rangifer tarandus'' L. По Пространству Евразии В Связи С Особенностями Его Деления На Подвиды |trans-title=Genetic Differentiation of the Reindeer ''Rangifer tarandus'' L. Across Eurasia in Connection with the Peculiarities of Its Division into Subspecies |journal=Кролиководство И Звероводство |trans-journal=Rabbit Breeding and Fur Farming |department=Геномика [Genomics] |issue=2 |pages=23–36 |language=ru |doi=10.24411/0023-4885-2020-10203 |doi-broken-date=1 November 2024 }}</ref> Siberian tundra reindeer herds have been in decline but are stable or increasing since 2000.<ref name="Mizin-2018b" />

Insular (island) reindeer, classified as the Novaya Zemlya reindeer (''R. t. pearsoni'') occupy several island groups: the [[Novaya Zemlya]] Archipelago (about 5,000 animals at last count, but most of these are either domestic reindeer or domestic-wild hybrids), the [[New Siberia]] Archipelago (about 10,000 to 15,000), and [[Wrangel Island]] (200 to 300 feral domestic reindeer).<ref name="Mizin-2018a" />

What was once the second largest herd is the migratory Labrador caribou (''R. t. caboti'')<ref name="Harding-2022" /> [[Migratory woodland caribou#George River caribou herd (GRCH)|George River herd]] in Canada, with former variations between 28,000 and 385,000. As of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the [[Canadian Broadcasting Corporation]].<ref>{{Cite news|url=http://www.cbc.ca/news/canada/newfoundland-labrador/george-river-caribou-ban-5-years-1.4506775|title=Tradition 'snatched away': Labrador Inuit struggle with caribou hunting ban {{!}} CBC News|work=CBC|access-date=18 April 2018|language=en-U.S.}}</ref> ''[[The New York Times]]'' reported in April 2018 of the disappearance of the only herd of southern mountain woodland caribou in the [[contiguous United States]], with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals.<ref>{{Cite news |url=https://www.nytimes.com/2018/04/14/science/gray-ghost-caribou-extinct.html|title=Gray Ghosts, the Last Caribou in the Lower 48 States, Are 'Functionally Extinct'|last=Robbins|first=Jim|date=14 April 2018|work=The New York Times|access-date=18 April 2018|language=en-US|issn=0362-4331}}</ref> After the last individual, a female, was translocated to a wildlife rehabilitation center in Canada, caribou were considered extirpated from the [[contiguous United States]].<ref>{{cite web|url=https://wdfw.wa.gov/species-habitats/species/rangifer-tarandus#desc-range|title = Woodland caribou}}</ref> The [[Committee on the Status of Endangered Wildlife in Canada]] (COSEWIC) classified both the Southern Mountain population DU9 (''R. t. montanus'') and the Central Mountain population DU8 (''R. t. fortidens'') as Endangered and the Northern Mountain population DU7 (''R. t. osborni'') as Threatened.<ref>{{cite report |author=COSEWIC |date=2014 |title=COSEWIC assessment and status report on the caribou ''Rangifer tarandus'', Northern Mountain population, Central Mountain population and Southern Mountain population in Canada |place=Ottawa, Ontario |publisher=Committee on the Status of Endangered Wildlife in Canada (COSEWIC) |url=https://wildlife-species.canada.ca/species-risk-registry/virtual_sara/files/cosewic/sr_Caribou_Northern_Central_Southern_2014_e.pdf}}</ref>

Some species and subspecies are rare and three subspecies have already become extinct: the [[Queen Charlotte Islands caribou]] (''R. t. dawsoni'') from western Canada, the Sakhalin reindeer (''R. t. setoni'') from [[Sakhalin]] and the [[Arctic reindeer|East Greenland caribou]] from eastern Greenland,<ref name="HighArctic">{{cite journal |author1=Peter Gravlund |author2=Morten Meldgaard |author3=Svante Pääbo |author4=Peter Arctander |name-list-style=amp |title= Polyphyletic Origin of the Small-Bodied, High-Arctic Subspecies of Tundra Reindeer (''Rangifer tarandus'')|volume= 10|doi=10.1006/mpev.1998.0525|year=1998 |journal=Molecular Phylogenetics and Evolution|issue=2|pages=151–159|pmid=9878226|bibcode=1998MolPE..10..151G }}</ref><ref name="dawsoni" /><ref name="eogroenlandicus">{{cite journal |author1=Degerbøl Magnus|title=The extinct reindeer of East-Greenland: ''Rangifer tarandus eogroenlandicus'', subsp. nov.: compared with reindeer from other Arctic regions|volume=10|year=1957|journal=Acta Arctica|pages=1–57}}</ref> although some authorities believe that the latter, ''R. t. eogroenlandicus'' Degerbøl, 1957, is a junior synonym of the Peary caribou.<ref>{{Cite journal |last=Meldgaard |first=M. |date=1986 |title=The Greenland caribou - zoogeography, taxonomy and population dynamics |journal=Kommissionen for Videnskabelige Undersagelser i Grønland, Meddelelser om Grønland, Bioscience |volume=20 |pages=1–88}}</ref><ref>{{Cite journal |last=Bennike |first=Ole |date=1988-01-01 |title=Review: The Greenland Caribou - Zoogeography, Taxonomy and Population Dynamics, by Morten Meldgaard |journal=Arctic |volume=41 |issue=2 |pages=146–147 |doi=10.14430/arctic1984 |issn=1923-1245|doi-access=free }}</ref><ref name="Harding-2022" /> Historically, the range of the sedentary boreal woodland caribou covered more than half of Canada<ref name="CPWS">{{cite web |url=http://www.davidsuzuki.org/publications/BorealCaribouReport-CPAWS_DSF.pdf |title=Population Critical: How are Caribou Faring?|date=December 2013|website=Canadian Parks and Wilderness Society and The David Suzuki Foundation|access-date=17 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20131219102733/http://www.davidsuzuki.org/publications/BorealCaribouReport-CPAWS_DSF.pdf|archive-date=19 December 2013}}</ref> and into the northern states of the [[contiguous United States]] from [[Maine]] to [[Washington (state)|Washington]]. Boreal woodland caribou have disappeared from most of their original southern range and were designated as Threatened in 2002 by the [[Committee on the Status of Endangered Wildlife in Canada]] (COSEWIC).<ref name="COSEWIC2011DUReport">{{citation |title=Designatable Units for Caribou (''Rangifer tarandus'') in Canada |url=http://www.cosewic.gc.ca/eng/sct12/COSEWIC_Caribou_DU_Report_23Dec2011.pdf |work=COSEWIC |year=2011 |institution=Committee on the Status of Endangered Wildlife in Canada |location=Ottawa, Ontario |page=88 |access-date=18 December 2013|url-status=dead |archive-url=https://web.archive.org/web/20170103012527/http://www.cosewic.gc.ca/eng/sct12/COSEWIC_Caribou_DU_Report_23Dec2011.pdf |archive-date=2017-01-03}}</ref> [[Environment and Climate Change Canada]] reported in 2011 that there were approximately 34,000 [[boreal woodland caribou]] in 51 ranges remaining in Canada (Environment Canada, 2011b),<ref name="EC2012">{{citation|url=http://www.ec.gc.ca/ae-ve/6AE7146E-0991-4C2F-BE2F-E89DF4F8ED1E/13-018_EC_ID_1568_PDF_accessible_ANG.pdf|work=Environment Canada|title=Evaluation of Programs and Activities in Support of the Species at Risk Act|date=24 September 2012|access-date=27 December 2013|pages= 2, 9|url-status=live|archive-url=https://web.archive.org/web/20131227234223/http://www.ec.gc.ca/ae-ve/6AE7146E-0991-4C2F-BE2F-E89DF4F8ED1E/13-018_EC_ID_1568_PDF_accessible_ANG.pdf|archive-date=27 December 2013}}</ref> although those numbers included montane populations classified by Harding (2022) into subspecies of the Arctic caribou.<ref name="Harding-2022" /> Siberian tundra reindeer herds are also in decline, and ''Rangifer'' as a whole is considered to be Vulnerable by the [[International Union for Conservation of Nature]] (IUCN).

== Naming ==
[[Charles Hamilton Smith]] is credited with the name ''Rangifer'' for the reindeer genus,<ref name="ITZN-1958">{{Cite book |title=Opinion 91 Thirty-five generic names of mammals placed in the Official List of Generic Names In: Hemming, F. (Ed.) Smithsonian Miscellaneous Collections, Opinions and declarations, Opinions rendered by the International Commission of Zoological Nomenclature, Opinions 91 TO 97 |publisher=International Trust for Zoological Nomenclature |year=1958 |location=London, U.K. |pages=337–338}}</ref> which [[Albertus Magnus]] used in his {{lang|la|De animalibus}}, fol. Liber 22, Cap. 268: "Dicitur Rangyfer quasi ramifer". This word may go back to the [[Sámi languages|Sámi]] word {{lang|smi|raingo}}.<ref name="Sarauw" /> [[Carl Linnaeus]] chose the word ''tarandus'' as the specific epithet, making reference to [[Ulisse Aldrovandi]]'s {{lang|la|Quadrupedum omnium bisulcorum historia}} fol. 859–863, Cap. 30: De Tarando (1621). However, Aldrovandi and [[Conrad Gessner]]<ref>Gesner, K. (1617) {{lang|la|Historia animalium. Liber 1, De quadrupedibus viviparis}}. Tiguri 1551. p. 156: De Tarando. 9. 950: De Rangifero.</ref> thought that ''rangifer'' and ''tarandus'' were two separate animals.<ref>Aldrovandi, U. (1621) {{lang|la|Quadrupedum omnium bisulcorum historia}}. Bononiæ. Cap. 30: De Tarando– Cap. 31: De Rangifero.</ref> In any case, the ''tarandos'' name goes back to [[Aristotle]] and [[Theophrastus]].

The use of the terms ''reindeer'' and ''caribou'' for essentially the same animal can cause confusion, but the [[International Union for Conservation of Nature|ICUN]] clearly delineates the issue: "Reindeer is the European name for the species of ''Rangifer,'' while in North America, ''Rangifer'' species are known as Caribou."<ref name="iucn status 19 November 2021" /><ref name="ADF&G _profile">{{cite web | title=Caribou Species Profile | website=Alaska Department of Fish and Game (ADF&G) | url=https://www.adfg.alaska.gov/index.cfm?adfg=caribou.main | access-date=January 13, 2024}}</ref> The word ''[[wikt:reindeer|reindeer]]'' is an anglicized version of the [[Old Norse]] words {{lang|non|hreinn}} ("reindeer") and {{lang|non|dýr}} ("animal") and has nothing to do with reins.<ref name="Ref_">{{cite book|chapter-url=http://www.bartleby.com/61/75/D0087500.html|archive-url=https://web.archive.org/web/20040325232020/http://www.bartleby.com/61/75/D0087500.html|archive-date=25 March 2004|chapter=deer|publisher=Houghton Mifflin Company|title=The American Heritage Dictionary of the English Language, 4th ed. |year= 2000}}</ref> The word ''caribou'' comes through French, from the [[Mi'kmaq language|Mi'kmaq]] {{lang|mic|qalipu}}, meaning "snow shoveler", and refers to its habit of pawing through the snow for food.<ref>Flexner, Stuart Berg and Leonore Crary Hauck; eds. (1987). ''The Random House Dictionary of the English Language'', 2nd ed. (unabridged). New York: Random House, pp. 315–16</ref>

Because of its importance to many cultures, ''Rangifer'' and some of its species and subspecies have names in many languages. [[Inuvialuit]] of the western [[Northern Canada|Canadian Arctic]] and [[Inuit]] of the eastern Canadian Arctic, who speak different dialects of the [[Inuit languages]], both call the barren-ground caribou {{lang|iu-Latn|tuktu}}.<ref>Spalding, Alex, ''Inuktitut – A Multi-Dialectal Outline Dictionary (with an Aivilingmiutaq base)''. Nunavut Arctic College, Iqaluit, Nunavut, Canada, 1998.</ref><ref>{{lang|de|Eskimoisches Wörterbuch, gesammelt von den Missionaren in Labrador, revidirt und herausgegeben von Friedrich Erdmann}}. Budissin [mod. Bautzen] 1864.</ref><ref>[http://library.alaska.gov/hist/hist_docs/docs/anlm/200078.pdf Iñupiat Eskimo dictionary] {{webarchive|url=https://web.archive.org/web/20170202113016/http://library.alaska.gov/hist/hist_docs/docs/anlm/200078.pdf |date=2 February 2017 }}, ''[[Alaska State Library]]'', Donald H. Webster & Wilfried Zibell, 1970. Retrieved 23 March 2017.</ref> The Wekʼèezhìi ([[Tłı̨chǫ]]) people, a [[Dene]] (Athapascan) group, call the Arctic caribou {{lang|dgr|Ɂekwǫ̀}} and the boreal woodland caribou {{lang|dgr|tǫdzı}}.<ref>{{Cite web |date=2021 |title=Highlight on a Species at Risk - Tǫdzı (Boreal Caribou) |url=https://wrrb.ca/news/highlight-species-risk-todzi-boreal-caribou |access-date=15 November 2022 |website=Wek’èezhìi Renewable Resources Board}}</ref> The [[Gwichʼin]] (also a Dene group) have over 24 distinct caribou-related words.<ref name="FirstVoices">{{citation|title=Vuntut Gwich'in|url=http://www.firstvoices.com/en/Vuntut-Gwichin/words|work=First Voices|date=2001–2013|access-date=17 January 2014}}</ref>

Reindeer are also called {{lang|kl|tuttu}} by the [[Greenlandic Inuit]]<ref>Jerry McCarthy. [https://web.archive.org/web/20030524130231/http://www.geocities.com/jerry_mccarthy_uk/grnvocab.pdf Greenlandic word list.] Reindeer are called {{lang|kl|tuttu}} (pl {{lang|kl|tuttut}}) by the Greenlandic Inuit.</ref> and {{lang|is|hreindýr}}, sometimes {{lang|is|rein}}, by the [[Icelanders]].

== Evolution ==
The "glacial-interglacial cycles of the [[Late Pleistocene|upper Pleistocene]] had a major influence on the evolution" of ''Rangifer'' species and other Arctic and sub-Arctic species. Isolation of tundra-adapted species ''Rangifer'' in [[Last Glacial Maximum refugia]] during the last glacial – the [[Wisconsin glaciation]] in North America and the [[Weichselian glaciation]] in Eurasia – shaped "intraspecific [[genetic variability]]" particularly between the North American and Eurasian parts of the [[Arctic]].<ref name="Flagstad">{{cite journal |last1=Flagstad |first1=Oystein |last2=Roed |first2=Knut H. |year=2003 |title=Refugial origins of reindeer (''Rangifer tarandus'' L) inferred from mitochondrial DNA sequences |url=http://genome-lab.ucdavis.edu/LabMeeting/Lab_Meeting_Papers/temporary/Flagstad2003Evol.pdf |url-status=dead |journal=Evolution |volume=57 |pages=658–670 |doi=10.1554/0014-3820(2003)057[0658:roorrt]2.0.co;2 |pmid=12703955 |archive-url=https://web.archive.org/web/20060904024954/http://genome-lab.ucdavis.edu/LabMeeting/Lab_Meeting_Papers/temporary/Flagstad2003Evol.pdf |archive-date=4 September 2006 |access-date=4 January 2013 |number=3}}</ref>

Reindeer / caribou (''Rangifer'') are in the subfamily [[Capreolinae|Odocoileinae]], along with [[roe deer]] (''[[Capreolus]]''), [[Moose|Eurasian elk / moose]] (''Alces''), and [[water deer]] (''Hydropotes''). These antlered cervids split from the horned ruminants ''[[Bos]]'' (cattle and yaks), ''[[Ovis]]'' (sheep) and ''[[Capra (genus)|Capra]]'' (goats) about 36 million years ago.<ref name="Weldenegodguad-2020">{{Cite journal |last1=Weldenegodguad |first1=Melak |last2=Pokharel |first2=Kisun |last3=Ming |first3=Yao |last4=Honkatukia |first4=Mervi |last5=Peippo |first5=Jaana |last6=Reilas |first6=Tiina |last7=Røed |first7=Knut H. |last8=Kantanen |first8=Juha |date=December 2020 |title=Genome sequence and comparative analysis of reindeer (''Rangifer tarandus'') in northern Eurasia |journal=[[Scientific Reports]] |language=en |volume=10 |issue=1 |pages=8980 |doi=10.1038/s41598-020-65487-y |pmid=32488117 |pmc=7265531 |bibcode=2020NatSR..10.8980W |issn=2045-2322}}</ref> The Eurasian [[clade]] of Odocoileinae (Capreolini, Hydropotini and Alcini) split from the New World tribes of Capreolinae ([[Odocoileini]] and Rangiferini) in the [[Late Miocene]], 8.7–9.6 million years ago.<ref>{{Cite book |last=Croitor |first=Roman |title=Plio-Pleistocene deer of Western Palearctic: taxonomy, systematics, phylogeny |publisher=Institute of Zoology of the Academy of Sciences of Moldova |year=2018 |location=Chișinău, Moldova |pages=1–142}}</ref> ''Rangifer'' "evolved as a mountain deer, ...exploiting the subalpine and alpine meadows...".<ref name="Geist1998" /> ''Rangifer'' originated in the [[Piacenzian|Late Pliocene]] and diversified in the [[Early Pleistocene]], a 2+ million-year period of multiple glacier advances and retreats. Several named ''Rangifer'' fossils in [[Eurasia]] and North America predate the evolution of modern tundra reindeer.

Archaeologists distinguish "modern" tundra reindeer and barren-ground caribou from primitive forms – living and extinct – that did not have adaptations to extreme cold and to long-distance migration. They include a broad, high muzzle to increase the volume of the nasal cavity to warm and moisten the air before it enters the throat and lungs, bez tines set close to the brow tines, distinctive coat patterns, short legs and other adaptations for running long distances, and multiple behaviors suited to tundra, but not to forest (such as synchronized calving and aggregation during rutting and post-calving).<ref>{{Cite book |last=Croitor |first=Roman |title=Plio-Pleistocene deer of Western Palearctic: taxonomy, systematics, phylogeny |publisher=Institute of Zoology of the Academy of Sciences of Moldova |year=2018 |location=Chișinău}}</ref> As well, many genes, including those for [[vitamin D]] metabolism, [[Lipid metabolism|fat metabolism]], retinal development, [[circadian rhythm]], and tolerance to cold temperatures, are found in tundra caribou that are lacking or rudimentary in forest types.<ref>{{Cite journal |last1=Cavedon |first1=Maria |last2=Gubili |first2=Chrysoula |last3=Heppenheimer |first3=Elizabeth |last4=vonHoldt |first4=Bridgett |last5=Mariani |first5=Stefano |last6=Hebblewhite |first6=Mark |last7=Hegel |first7=Troy |last8=Hervieux |first8=Dave |last9=Serrouya |first9=Robert |last10=Steenweg |first10=Robin |last11=Weckworth |first11=Byron V. |last12=Musiani |first12=Marco |date=April 2019 |title=Genomics, environment and balancing selection in behaviourally bimodal populations: The caribou case |url=https://onlinelibrary.wiley.com/doi/10.1111/mec.15039 |journal=Molecular Ecology |language=en |volume=28 |issue=8 |pages=1946–1963 |doi=10.1111/mec.15039 |pmid=30714247 |bibcode=2019MolEc..28.1946C |s2cid=73423576 |issn=0962-1083|hdl=20.500.11820/82fe4f52-d3f2-4970-ab52-8dbb97b997c1 |hdl-access=free }}</ref><ref>{{Cite bioRxiv |last1=Prunier |first1=Julien |last2=Carrier |first2=Alexandra |last3=Gilbert |first3=Isabelle |last4=Poisson |first4=William |last5=Albert |first5=Vicky |last6=Taillon |first6=Joëlle |last7=Bourret |first7=Vincent |last8=Côté |first8=Steeve D. |last9=Droit |first9=Arnaud |last10=Robert |first10=Claude |date=2021-07-23 |title=Copy number variations with adaptive potential in caribou (''Rangifer tarandus''): genome architecture and new annotated genome assembly |biorxiv=10.1101/2021.07.22.453386}} {{s2cid|236436985}}</ref> For this reason, forest-adapted reindeer and caribou could not survive in [[tundra]] or [[polar desert]]s. The oldest undoubted ''Rangifer'' fossil is from [[Omsk]], Russia, dated to 2.1-1.8 Ma.<ref>Bondarev, A.A.; Tesakov, A.S.; Simakova, A.N.; Dorogov, A.L. (2017) Reindeer (''Rangifer'') from Early Pleistocene of the south of Western Siberia (in Russian). In: Bogdanov, A.A.; others (eds.) Integrative palaeontology: development prospects for geological objectives, material of the LXIII session of the Palaeontological Society, April, 3-7, 2017. Sankt-Peterburg, 173-175.</ref> The oldest North American ''Rangifer'' fossil is from the [[Yukon]], 1.6 million years before present (BP).<ref>{{Cite journal |last=Harington |first=C.R. |date=August 2011 |title=Pleistocene vertebrates of the Yukon Territory |journal=Quaternary Science Reviews |volume=30 |issue=17–18 |pages=2341–2354 |doi=10.1016/j.quascirev.2011.05.020 |bibcode=2011QSRv...30.2341H |issn=0277-3791}}</ref> A fossil skull fragment from Süßenborn, Germany, ''R. arcticus stadelmanni'',<ref>{{Cite journal |last=Kahlke |first=H-D |title=Die Cerviden-Reste aus den Kiesen von Süßenborn bei Weimar. Palaeontologische Abhandlungen Abteilung A |journal=Palaozoologie |volume=1969 |pages=367–788}}</ref> (which is probably misnamed) with "rather thin and cylinder-shaped" antlers, dates to the [[Chibanian|Middle Pleistocene]] (Günz) Period, 680,000-620,000 BP.<ref name="Croitor-2010">{{Cite journal |last=Croitor |first=Roman |date=2010 |title=Preliminary data on reindeer fossils from the Palaeolithic site Rascov-8 (eastern Moldova) with remarks on systematics and evolution of Upper Pleistocene reindeer |journal=Ştiinţele Naturii |volume=1 |pages=323–330}}</ref> ''Rangifer'' fossils become increasingly frequent in circumpolar deposits beginning with the [[Riss glaciation]]s, the second youngest of the [[Pleistocene]] Epoch, roughly 300,000–130,000 BP. By the [[Würm glaciation|4-Würm period]] (110,000–70,000 to 12,000–10,000 BP), its European range was extensive, supplying a major food source for prehistoric Europeans.<ref>{{Cite book |last=Kurtén |first=B. |title=Pleistocene mammals in Europe |publisher=Weidenfeld and Nicolson |year=1968 |issn=0345-0074 |location=London, U.K.}}</ref> North American fossils outside of [[Beringia]] that predate the [[Last Glacial Maximum]] (LGM) are of [[Rancholabrean]] age (240,000–11,000 years BP) and occur along the fringes of the Rocky Mountain and [[Laurentide ice sheet]]s as far south as northern [[Alabama]]; and in [[Sangamonian]] deposits (~100,000 years BP) from western Canada.<ref name="Geist-2007">{{Cite journal |last=Geist |first=Valerius |date=2007-04-01 |title=Defining subspecies, invalid taxonomic tools, and the fate of the woodland caribou |journal=[[Rangifer (journal)|Rangifer]] |volume=27 |issue=4 |pages=25 |doi=10.7557/2.27.4.315 |issn=1890-6729|doi-access=free }}</ref>

A ''R. t. pearyi''-sized caribou occupied Greenland before and after the LGM and persisted in a relict enclave in northeastern Greenland until it went extinct about 1900 (see discussion of ''R. t. eogroenlandicus'' below). Archaeological excavations showed that larger barren-ground-sized caribou appeared in western Greenland about 4,000 years ago.<ref name="HighArctic2">{{cite journal |author1=Peter Gravlund |author2=Morten Meldgaard |author3=Svante Pääbo |author4=Peter Arctander |name-list-style=amp |year=1998 |title=Polyphyletic Origin of the Small-Bodied, High-Arctic Subspecies of Tundra Reindeer (''Rangifer tarandus'') |journal=Molecular Phylogenetics and Evolution |volume=10 |issue=2 |pages=151–159 |doi=10.1006/mpev.1998.0525 |pmid=9878226|bibcode=1998MolPE..10..151G }}</ref>

The late [[Valerius Geist]] (1998)<ref name="Geist1998" /> dates the Eurasian reindeer radiation dates to the large Riss glaciation (347,000 to 128,000 years ago), based on the Norwegian-Svalbard split 225,000 years ago.<ref>Røed, K.H. (1985) Comparison of the genetic variation in Svalbard and Norwegian reindeer. Canadian Journal of Zoology 63: 2038-2042. {{doi|10.1139/z85-300}}</ref> Finnish forest reindeer (''R. t. fennicus'') likely evolved from ''Cervus [Rangifer] geuttardi'' Desmarest, 1822, a reindeer that adapted to forest habitats in Eastern Europe as forests expanded during an interglacial period before the LGM (the Würmian or [[Weichsel glaciation]]);.<ref name="Croitor-2010" /> The fossil species ''geuttardi'' was later replaced by ''R. constantini'', which was adapted for grasslands,<ref>{{Cite journal |last1=Baranova |first1=A. I. |last2=Panchenko |first2=D. V. |last3=Kholodova |first3=M. V. |last4=Tirronen |first4=K. F. |last5=Danilov |first5=P. I. |date=November 2016 |title=Genetic diversity of wild reindeer ''Rangifer tarandus'' L. from the eastern part of the Kola Peninsula: Polymorphism of the mtDNA control region |journal=Biology Bulletin |volume=43 |issue=6 |pages=567–572 |doi=10.1134/s1062359016060029 |bibcode=2016BioBu..43..567B |s2cid=15672189 |issn=1062-3590}}</ref> in a second immigration 19,000–20,000 years ago when the LGM turned its forest habitats into tundra, while ''fennicus'' survived in isolation in southwestern Europe.<ref name="Croitor-2010" /> ''R. constantini'' was then replaced by modern tundra / barren-ground caribou adapted to extreme cold, probably in Beringia, before dispersing west (''R. t. tarandus'' in the [[Scandinavia]]n mountains and ''R. t. sibiricus'' across Siberia) and east (''R. t. arcticus'' in the North American Barrenlands) when rising seas isolated them. Likewise in North America, [[Genetic testing|DNA analysis]] shows that woodland caribou (''R. caribou'') diverged from primitive ancestors of tundra / barren-ground caribou not during the LGM, 26,000–19,000 years ago, as previously assumed, but in the Middle Pleistocene around 357,000 years ago.<ref name="Horn-2018">{{Cite journal |last1=Horn |first1=Rebekah L. |last2=Marques |first2=Adam J. D. |last3=Manseau |first3=Micheline |last4=Golding |first4=Brian |last5=Klütsch |first5=Cornelya F. C. |last6=Abraham |first6=Ken |last7=Wilson |first7=Paul J. |date=June 2018 |title=Parallel evolution of site-specific changes in divergent caribou lineages |journal=Ecology and Evolution |language=en |volume=8 |issue=12 |pages=6053–6064 |doi=10.1002/ece3.4154 |pmid=29988428 |pmc=6024114|bibcode=2018EcoEv...8.6053H }}</ref><ref name="Yannic-2018">{{Cite journal |last1=Yannic |first1=Glenn |last2=Ortego |first2=Joaquín |last3=Pellissier |first3=Loïc |last4=Lecomte |first4=Nicolas |last5=Bernatchez |first5=Louis |last6=Côté |first6=Steeve D. |date=2018 |title=Linking genetic and ecological differentiation in an ungulate with a circumpolar distribution |journal=Ecography |volume=41 |issue=6 |pages=922–937 |doi=10.1111/ecog.02995 |bibcode=2018Ecogr..41..922Y |issn=0906-7590 |s2cid=4518424|doi-access=free }}</ref> At that time, modern tundra caribou had not even evolved. Woodland caribou are likely more related to extinct North American forest caribou than to barren-ground caribou. For example, the extinct caribou ''Torontoceros [Rangifer] hypogaeus'', had features (robust and short pedicles, smooth antler surface, and high position of second tine) that relate it to forest caribou.<ref>{{Cite journal |last=Croitor |first=Roman |date=2022 |title=Paleobiogeography of Crown Deer |journal=Earth |volume=3 |issue=4 |pages=1138–1160|doi=10.3390/earth3040066 |bibcode=2022Earth...3.1138C |doi-access=free }}</ref>

Humans started hunting reindeer in both the [[Mesolithic]] and [[Neolithic]] Periods, and humans are today the main predator in many areas. [[Norway]] and [[Greenland]] have unbroken traditions of hunting wild reindeer from the [[Last Glacial Period]] until the present day. In the non-forested mountains of central Norway, such as [[Jotunheimen]], it is still possible to find remains of stone-built [[trapping pit]]s, guiding fences and bow rests, built especially for hunting reindeer. These can, with some certainty, be dated to the [[Migration Period]], although it is not unlikely that they have been in use since the [[Stone Age]].

[[Cave painting]]s by ancient Europeans include both tundra and forest types of reindeer.<ref name="Geist1998" />

A 2022 study of ancient [[environmental DNA]] from the [[Early Pleistocene]] (2 million years ago) [[Kap Kobenhavn Formation]] of northern Greenland identified preserved DNA fragments of ''Rangifer'', identified as basal but potentially ancestral to modern reindeer. This suggests that reindeer have inhabited Greenland since at least the Early Pleistocene. Around this time, northern Greenland was {{cvt|11|–|19|C-change}} warmer than the [[Holocene]], with a [[Taiga|boreal forest]] hosting a species assemblage with no modern analogue. These are among the oldest DNA fragments ever sequenced.<ref>{{Cite journal |last1=Kjær |first1=Kurt H. |last2=Winther Pedersen |first2=Mikkel |last3=De Sanctis |first3=Bianca |last4=De Cahsan |first4=Binia |last5=Korneliussen |first5=Thorfinn S. |last6=Michelsen |first6=Christian S. |last7=Sand |first7=Karina K. |last8=Jelavić |first8=Stanislav |last9=Ruter |first9=Anthony H. |last10=Schmidt |first10=Astrid M. A. |last11=Kjeldsen |first11=Kristian K. |last12=Tesakov |first12=Alexey S. |last13=Snowball |first13=Ian |last14=Gosse |first14=John C. |last15=Alsos |first15=Inger G. |date=December 2022 |title=A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA |journal=Nature |language=en |volume=612 |issue=7939 |pages=283–291 |doi=10.1038/s41586-022-05453-y |issn=1476-4687 |pmc=9729109 |pmid=36477129|bibcode=2022Natur.612..283K }}</ref><ref>{{Cite web |last=Pappas |first=Stephanie |title=World's Oldest DNA Discovered, Revealing Ancient Arctic Forest Full of Mastodons |url=https://www.scientificamerican.com/article/worlds-oldest-dna-discovered-revealing-ancient-arctic-forest-full-of-mastodons/ |access-date=2022-12-08 |website=Scientific American |language=en}}</ref>

== Taxonomy ==

=== Naming and research on museum collections ===
[[Carl Linnaeus]] in 1758 named the Eurasian tundra species ''Cervus tarandus'', the genus ''Rangifer'' being credited to Smith, 1827.<ref name="ITZN-1958" />

''Rangifer'' has had a convoluted history because of the similarity in antler architecture (brow tines asymmetrical and often palmate, bez tines, a back tine sometimes branched, and branched at the distal end, often palmate).{{Citation needed|date=September 2024}} Because of individual variability, early taxonomists were unable to discern consistent patterns among populations, nor could they, examining collections in Europe, appreciate the difference in habitats and the differing function they imposed on antler architecture.{{Citation needed|date=September 2024}} Comparative morphometrics, the measurement of skulls, is often seen as more objective than description of differences of color or antler patterns, but actually confounds genetic variance with epistatic and statistical variance as well as compounded environment-based variance.<ref name="Geist-2007" />

For example, woodland caribou males, rutting in boreal forest where only a few females can be found, collect harems and defend them against other males, for which they have short, straight, strong, much-branched antlers, beams flattened in cross-section, designed for combat — and not too large, so as not to impede them in forested winter ranges.{{Citation needed|date=September 2024}}

By contrast, modern tundra caribou (see [[Reindeer#Evolution|Evolution]] above) have synchronized calving as a predator-avoidance strategy, which requires large rutting aggregations.{{Citation needed|date=September 2024}} Males cannot defend a harem because, while he was busy fighting, they would disappear into the mass of the herd. Males therefore tend individual females; their fights are infrequent and brief.{{Citation needed|date=September 2024}} Their antlers are thin, beams round in cross-section, sweep back and then forward with a cluster of branches at the top; these are designed more for visual stimulation of the females.{{Citation needed|date=September 2024}} Their bez tines are set low, just above the brow tine, which is vertically flattened to protect the eyes while the buck "threshes" low brush, a courtship display.<ref>{{Cite journal |last=Pruitt Jr. |first=William |date=1966 |title=The Function of the Brow-Tine in Caribou Antlers |journal=Arctic |volume=19 |issue=2 |pages=110–113|doi=10.14430/arctic3419 |doi-access=free }}</ref> The low bez tines help the wide flat brow tines dig craters in the hard-packed tundra snow for forage, for which reason brow tines are often called "shovels" in North America and "ice tines" in Europe. The differences in antler architecture reflect fundamental differences in ecology and behavior, and in turn deep divisions in ancestry that were not apparent to the early taxonomists.

Similarly, working on museum collections where skins were often faded and in poor states of preservation, early taxonomists could not readily perceive differences in coat patterns that are consistent within a subspecies, but variable among them. Geist calls these "nuptial" characteristics: sexually selected characters that are highly conserved and diagnostic among subspecies.<ref name="Geist1998" /><ref name="Geist-2007" />

=== Biological exploration expeditions ===
Towards the end of the 19th century, national museums began sending out biological exploration expeditions and collections accumulated. Taxonomists, usually working for the museums, began naming subspecies more rigorously, based on statistical differences in detailed cranial, dental and skeletal measurements than antlers and pelage, supplemented by better knowledge of differences in ecology and behavior. From 1898 to 1937, [[mammalogist]]s named 12 new species (other than barren-ground and woodland, which had been named earlier) of caribou in Canada and Alaska, and three new species and nine new subspecies in Eurasia, each properly described according to the evolving rules of zoological nomenclature, with type localities designated and type specimens deposited in museums (see table in [[Reindeer#Species and subspecies|Species and subspecies]] below).<ref name="Harding-2022" /><ref name="Harding-2022-2">{{Cite web |last=Harding |first=Lee E. |date=2022a |title=Synonymy |url=https://zookeys.pensoft.net/article/80233/download/suppl/31/}} Supplementary file 1 for {{harvp|Harding|2022}}.</ref>

=== Reclassification ===
In the mid-20th century, as definitions of "species" evolved,{{How|date=September 2024}} mammalogists in Europe<ref>{{Cite book |last=Ellerman |first=J. E. |title=Checklist of Palaearctic and Indian mammals, 1758 to 1946 |publisher=British Natural History Museum |year=1951 |location=London, U.K. |pages=1–810}}</ref> and North America<ref name="Banfield-1961">{{Cite book |last=Banfield |first=Alexander William Francis |title=A Revision of the Reindeer and Caribou, Genus Rangifer |publisher=National Museum of Canada Bulletin 177 Biological Series No. 66 |year=1961 |location=Ottawa, Ontario |pages=1–187}}</ref> made all ''Rangifer'' species conspecific with ''R. tarandus'', and synonymized most of the subspecies. [[Alexander William Francis Banfield]]'s often-cited ''A Revision of the Reindeer and Caribou, Genus Rangifer'' (1961),<ref name="Banfield_1961">{{Cite journal|last=Banfield |first=Alexander William Francis|year=1961|title=A Revision of the Reindeer and Caribou, Genus Rangifer |journal=Bulletin of the National Museum of Canada |volume=177 |number=66 |series=Biological Services}}</ref> eliminated ''R. t. caboti'' (the [[Labrador]] caribou), ''R. t. osborni'' (Osborn's caribou — from [[British Columbia]]) and ''R. t. terranovae'' (the [[Newfoundland (island)|Newfoundland]] caribou) as invalid and included only [[barren-ground caribou]], renamed as ''R. t. groenlandicus'' (formerly ''R. arcticus'') and woodland caribou as ''R. t. caribou''. However, Banfield made multiple errors, eliciting a scathing review by [[Ian McTaggart-Cowan]] in 1962.<ref>{{Cite journal |last=McTaggert-Cowan |first=Ian |date=1962 |title=Reviews: A revision of the reindeer and caribou, genus Rangifer by A. W. F. Banfield 1961 |journal=Canadian Field-Naturalist |volume=76 |pages=168–169 |doi=10.5962/p.342032 |oclc=1029734421|doi-access=free }}</ref> Most authorities continued to consider all or most subspecies valid; some were quite distinct. In his chapter in the authoritative 2005 reference work ''Mammal Species of the World'',<ref name="MSW3" /> referenced by the [[American Society of Mammalogists]], English zoologist [[Peter Grubb (zoologist)|Peter Grubb]] agreed with [[Valerius Geist]], a specialist on large mammals,<ref name="Geist1998" /><ref name="Geist-2007" /> that these subspecies were valid (i.e., before the recent revision): In North America, ''R. t. caboti'', ''R. t. caribou'', ''R. t. dawsoni'', ''R. t. groenlandicus'', ''R. t. osborni'', ''R. t. pearyi'', and ''R. t. terranovae''; and in Eurasia, ''R. t. tarandus'', ''R. t. buskensis'' (called ''R. t. valentinae'' in Europe; see below), ''R. t. phylarchus'', ''R. t. pearsoni'', ''R. t. sibiricus'' and ''R. t. platyrhynchus''. These subspecies were retained in the 2011 replacement work ''[[Handbook of the Mammals of the World]] Vol. 2: Hoofed Mammals''.<ref name="HBW" /> Most Russian authors also recognized ''R. t. angustirostris'', a forest reindeer from east of [[Lake Baikal]].<ref>Flerov, C.C. (1952) Mammals: Musk deer and deer. In: Fauna of the USSR. Academy of Sciences, Moscow and Leningrad, USSR, 222-247.</ref><ref name="Mizin-2018b" /><ref name="Rozhkov-2020" />

However, since 1991, many genetic studies have revealed deep divergence between modern tundra reindeer and woodland caribou.<ref name="Røed, K.H. 1991">Røed, K.H.; Feruson, M.D.; Crête, M.; Bergerud, A.T. (1991) Genetic variation in transferrin as a predictor for differentiation and evolution of caribou from [[eastern Canada]]. Rangifer 11: 65-74.</ref><ref name="Flagstad" /><ref name="Courtois-2003">{{Cite journal |last=Courtois |first=Rehaume |date=2003 |title=Significance of caribou (''Rangifer tarandus'') ecotypes from a molecular genetics viewpoint |journal=[[Conservation Genetics]] |volume=4 |issue=3 |pages=393–404|doi=10.1023/A:1024033500799 |bibcode=2003ConG....4..393C |s2cid=34394002 }}</ref><ref>{{Cite book |last=Couturier |first=Serge |title=Populations, metapopulations, ecotypes and subspecies of caribou in Quebec & Labrador: an exploratory discussion. In: McFarlane, K.; Gunn, A.; Strobeck, C. (eds.) Proceedings from the Caribou Genetics and Relationships Workshop (K. and C. Strobeck, eds.) |publisher=Department of Natural Resources and Environment, Government of the Northwest Territories |year=2003 |location=[[Edmonton, Alberta]] |pages=59–70}}</ref><ref name="Cronin-2003">{{Cite journal |last=Cronin |first=Matthew A. |date=2003 |title=Genetic variation in caribou and reindeer (''Rangifer tarandus'') |journal=[[Animal Genetics]] |volume=34 |issue=1 |pages=33–41|doi=10.1046/j.1365-2052.2003.00927.x |pmid=12580784 }}</ref> Geist (2007) and others continued arguing that the woodland caribou was incorrectly classified, noting that "true woodland caribou, the uniformly dark, small-maned type with the frontally emphasized, flat-beamed antlers", is "scattered thinly along the southern rim of North American caribou distribution". He affirms that the "true woodland caribou is very rare, in very great difficulties and requires the most urgent of attention."<ref name="Geist">{{Cite journal |last1=Geist |first1=Valerius |year=2007 |title=Defining subspecies, invalid taxonomic tools, and the fate of the woodland caribou |journal=[[Rangifer (journal)|Rangifer]] |volume=27 |issue=4 |page=25 |doi=10.7557/2.27.4.315 |doi-access=free}}</ref>

==== Ecotypes ====
In 2011, noting that the former classifications of ''Rangifer tarandus'', either with prevailing [[taxonomy]] on subspecies, designations based on [[ecotype]]s, or natural population groupings, failed to capture "the variability of caribou across their range in Canada" needed for effective subspecies conservation and management, COSEWIC developed Designatable Unit (DU) attribution,<ref name="COSEWIC2011DUReport" /> an adaptation of "evolutionary significant units".<ref>{{Cite book |last=Waples |first=Robin S. |title=Evolutionary significant units and the conservation of biological diversity under the Endangered Species Act. In: Nielson, J.L. (ed.) Evolution and the aquatic ecosystem: Defining unique units in population conservation |publisher=American Fisheries Society Symposium 17 |year=1995 |location=Bethesda, Maryland |pages=8–27}}</ref> The 12 designatable units for caribou in Canada (that is, excluding Alaska and Greenland) based on ecology, behavior and, importantly, genetics (but excluding [[Morphology (biology)|morphology]] and archaeology) essentially followed the previously named subspecies distributions, without naming them as such, plus some ecotypes. Ecotypes are not [[Phylogenetics|phylogenetically]] based and cannot substitute for taxonomy.<ref>Cronin, M.A. (2006) A proposal to eliminate redundant terminology for intra-species groups. Wildlife Society Bulletin 34: 237-241.</ref>

==== Genetic, molecular, and archaeological evidence ====
Meanwhile, [[Genome|genetic data]] continued to accumulate, revealing sufficiently deep divisions to easily separate ''Rangifer'' back into six previously named species and to resurrect several previously named subspecies. Molecular data showed that the Greenland caribou (''R. t. groenlandicus'') and the [[Svalbard reindeer]] (''R. t. platyrhynchus''), although not closely related to each other, were the most genetically divergent among ''Rangifer'' clades;<ref name="Yannic-2013" /> that modern (see [[Reindeer#Evolution|Evolution]] above) Eurasian tundra reindeer (''R. t. tarandus'' and ''R. t. sibiricus'') and North American barren-ground caribou (''R. t. arcticus''), although sharing ancestry, were separable at the subspecies level; that Finnish forest reindeer (''R. t. fennicus'') clustered well apart from both wild and domestic tundra reindeer<ref name="Rozhkov-2020" /> and that boreal woodland caribou (''R. t. caribou'') were separable from all others.<ref name="mtDNA2">{{Cite journal |last1=Cronin |first1=M. A. |last2=MacNeil |first2=M. D. |last3=Patton |first3=J. C. |year=2005 |title=Variation in Mitochondrial Dna and Microsatellite Dna in Caribou (''Rangifer tarandus'') in North America |journal=Journal of Mammalogy |volume=86 |issue=3 |pages=495–505 |doi=10.1644/1545-1542(2005)86[495:VIMDAM]2.0.CO;2 |doi-access=free}}</ref><ref>Cronin, M.A.; MacNeil, M.D.; Patton, J.C. (2006) Mitochondrial DNA and microsatellite DNA variation in domestic reindeer (''Rangifer tarandus tarandus'') and relationships with wild caribou (''Rangifer tarandus granti'', ''Rangifer tarandus groenlandicus'', and ''Rangifer tarandus caribou''). Journal of Heredity 97: 525-530. {{doi|10.1093/jhered/esl012}}</ref> Meanwhile, archaeological evidence was accumulating that Eurasian forest reindeer descended from an extinct forest-adapted reindeer and not from tundra reindeer (see [[Reindeer#Evolution|Evolution]] above); since they do not share a direct [[Common descent|common ancestor]], they cannot be Biological specificity#conspecific|conspecific. Similarly, woodland caribou diverged from the ancestors of Arctic caribou before modern barren-ground caribou had evolved, and were more likely related to extinct North American forest reindeer (see [[Reindeer#Evolution|Evolution]] above). Lacking a direct shared ancestor, barren-ground and woodland caribou cannot be conspecific.

[[Sequencing|Molecular data]] also revealed that the four western Canadian  montane ecotypes are not woodland caribou: they share a common ancestor with modern barren-ground caribou / tundra reindeer, but distantly, having diverged > 60,000 years ago<ref>McDevitt, A.D.; Mariani, S.; Hebblewhite, M.; Decesare, N.J.; Morgantini, L.; Seip, D.R.; Weckworth, B.V.; Musiani. M. (2009) Survival in the Rockies of an endangered hybrid swarm from diverged caribou (''Rangifer tarandus'') lineages. Molecular Ecology 18: 665-679.</ref><ref name="Horn-2018" /><ref name="Yannic-2013">Yannic, G.; Pellissier, L.; Ortego, J.; Lecomte, N.; Couturier, S.; Cuyler, C.; Dussault, C.; Hundertmark, K.J.; Irvine, R.J.; Jenkins, D.A.; Kolpashikov, L.; Mager, K.; Musiani, M.; Parker, K.L.; Røed, K.H.; Sipko, T.; Þórisson, S.G.; V.Weckworth, B.; Guisan, A.; Bernatchez, L.; Côté, S.D. (2013) Genetic diversity in caribou linked to past and future climate change. Nature Climate Change 4: 132-137. {{doi|10.1038/NCLIMATE2074}}</ref> — before the modern ecotypes had evolved their cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors (see Evolution above). Before Banfield (1961), taxonomists using cranial, dental and skeletal measurements had unequivocally allied these western montane ecotypes with barren-ground caribou, naming them (as in Osgood 1909<ref name="Osgood-1909">Osgood, W.H. (1909) Biological investigations in Alaska and Yukon Territory. US Department of Agriculture Biological survey of North American fauna 1: 1-285.</ref> Murie, 1935<ref name="Murie-1935" /> and Anderson 1946,<ref name="Anderson-1946" /> among others) ''R. t. stonei'', ''R. t. montanus'', ''R. t. fortidens'' and ''R. t. osborni'', respectively,<ref name="Murie-1935">{{Cite book |last=Murie |first=Olaus J. |title=Alaska-Yukon caribou |publisher=United States Department of Agriculture Bureau of Biological Survey Vol. 54 |year=1935 |location=Washington D.C. |pages=1–93}}</ref><ref name="Anderson-1946">{{Cite book |last=Anderson |first=Rudolph M. |title=Catalogue of Canadian Recent Mammals |publisher=National Museum of Canada Bulletin No. 102, Biological Series 31 |year=1946 |location=Ottawa, Ontario |pages=1–238}}</ref> and this phylogeny was confirmed by genetic analysis.

==== Novel genetics-based clades ====
DNA also revealed three unnamed clades that, based on genetic distance, genetic divergence and shared vs. private [[haplotype]]s and [[allele]]s, together with ecological and behavioral differences, may justify separation at the subspecies level: the Atlantic-[[Gaspé Peninsula|Gaspésie]] caribou (COSEWIC DU11),<ref name="Courtois-2003" /><ref name="Yannic-2018" /> an eastern montane ecotype of the boreal woodland caribou, and the [[Baffin Island]] caribou.<ref name="Jenkins-2018">{{Cite journal |last=Jenkins |first=Deborah A. |date=2018 |title=Population structure of caribou in an ice-bound archipelago |journal=Diversity and Distributions |volume=24 |issue=8 |pages=1092–1108|doi=10.1111/ddi.12748 |bibcode=2018DivDi..24.1092J |s2cid=90854394 |doi-access=free }}</ref> Neither one of these clades has yet been formally described or named.

Jenkins et al. (2012) said that "[Baffin Island] caribou are unique compared to other Barrenground herds, as they do not overwinter in forested habitat, nor do all caribou undertake long seasonal migrations to calving areas." It also shares a mtDNA haplotype with Labrador caribou, in the North American lineage (i.e., woodland caribou).<ref name="mtDNA2"/> Røed et al. (1991)<ref name="Røed, K.H. 1991"/> had noted:<blockquote>Among Baffin Island caribou the TFL2 allele was the most common allele (p=0.521), while this allele was absent, or present in very low frequencies, in other caribou populations (Table 1), including the Canadian barren-ground caribou from the Beverly herd. A large genetic difference between Baffin Island caribou and the Beverly herd was also indicated by eight alleles found in the Beverly herd which were absent from the Baffin Island samples.</blockquote>Jenkins et al. (2018)<ref name="Jenkins-2018" /> also reported genetic distinctiveness of Baffin Island caribou from all other barren-ground caribou; its genetic signature was not found on the mainland or on other islands; nor were [[Reindeer distribution#Ahiak, Beverly and Qamanirjuaq caribou herds|Beverly herd]] (the nearest mainly barren-ground caribou) alleles present in Baffin Island caribou, evidence of reproductive isolation.

These advances in ''Rangifer'' genetics were brought together with previous morphological-based descriptions, ecology, behavior and archaeology to propose a new revision of the genus.<ref name="Harding-2022" />

== Species and subspecies ==

{| class="wikitable" style="text-align:center"
|+ Extant species and subspecies of ''Rangifer''
! width=9.5% | Species<br>(1-species taxonomy)
! width=10% | Species<br>(6-species taxonomy){{efn|The 6-species taxonomy is based on a revision by Harding (2022).<ref name="Harding-2022" /><ref name="Harding-2022-2" /><ref name="Harding-2022-3">{{cite web |last=Harding |first=Lee E. |date=2022b |title=Genetic distance |url=https://zookeys.pensoft.net/article/80233/download/suppl/32/}} Supplementary file 2 for {{harvp|Harding|2022}}.</ref>}}
! width=12.5% | Subspecies
! width=12.5% | Common name
! width=13% | Sedentary / migratory
! width=14.5% | Range
! width=13.5% | Weight of male
! width=14.5% | Type locality / specimen
|-
| rowspan="19" |''R. tarandus''<br>(Linnaeus, 1758)<br>''reindeer'' or ''caribou''
| rowspan="8" |''R. arcticus''<br>Richardson, 1829<br>''Barren-ground caribou''
|[[File:Barren ground caribou grazing with autumn foliage in background.jpg|180px]]<br />'' R. t. arcticus'' or<br>''R. a. articus''<br>(Richardson, 1829) ||[[barren-ground caribou]]|| migratory ||the [[Arctic Archipelago|High Arctic islands]] of [[Nunavut]] and the [[Northwest Territories]], Canada and western [[Greenland]] (except for the southwestern region)||{{cvt|150|kg}}
|"Fort Enterprise, Winter Lake, [[Mackenzie District]], N.W.T., Canada" given by Allen 1908; Neotype no. 22066 (for the species)
|-
|[[File:Caribou.jpg|180px]]<br />''R. t. arcticus'' or<br>''R. a. arcticus''<br>(Richardson, 1829)
|[[Porcupine caribou]] (an ecotype of the barren-ground caribou)
|migratory
|summers in the northern Yukon mountains and the coastal plains; winters in the [[Taiga|boreal forest]]s of [[Alaska]] and the [[Yukon]] 
|the same as for the subspecies
|
|-
|''R. t. fortidens'' or<br>''R. a. fortidens''<br>(Hollister, 1912)
|[[Rocky Mountain caribou]]
|short migrations: summers in alpine forest and winters in lowland forest
|the Canadian [[Rocky Mountains]]
|"Largest of the caribou, exceeding in measurements the largest specimens of ''Rangifer osborni'' and ''Rangifer montanus''."
|"head of Moose Pass branch of the [[Smoky River]], [[Alberta]] (north-east of [[Mount Robson]])"; USNM No. 174505
|-
|''R. t. granti'' or<br>''R. a. granti''<br>([[Joel Asaph Allen|Allen]], 1902)
|[[Porcupine caribou#Taxonomy|Grant's caribou]]
|sedentary (makes short movements to seasonal habitats)<ref name="Allen1902">{{Cite journal |last=Allen |first=J. A. |date=1902 |title=A new caribou from the Alaska Peninsula |url=https://digitallibrary.amnh.org/bitstream/handle/2246/1666//v2/dspace/ingest/pdfSource/bul/B016a10.pdf?sequence=1&isAllowed=y |journal=Bulletin of the American Museum of Natural History |volume=XVI |pages=119–127 |id=Article X |hdl=2246/1666}}</ref>{{rp|127}}
|the western end of the [[Alaska Peninsula]] and the adjacent islands<ref name="Allen1902" />{{rp|127}}
|
|"Western end of [[Alaska Peninsula]], opposite [[Popof Island|Popoff Island]], Alaska"; AMNH no. 17593<ref name="Allen1902" />{{rp|122}}
|-
|[[File:1999Mt-Caribou002 crop-AI.jpg|alt=Selkirk Mountain caribou|180px]]<br>''R. t. montanus'' or<br>''R. a. montanus''<br>(Seton-Thompson, 1899)
|[[Selkirk Mountains caribou]]
|twice-yearly altitudinal movements
|the [[Columbia Mountains]] (specifically the [[Selkirk Mountains|Selkirk]], [[Purcell Mountains|Purcell]] and [[Monashee Mountains]]) in [[British Columbia]], Canada and [[Washington (state)|Washington]], [[Idaho]] and [[Montana]], United States
|no data
|"[[Illecillewaet River|Illecillewaet]] watershed, near [[Revelstoke, British Columbia|Revelstoke]], [[Selkirk Mountains|Selkirk Range]], [[British Columbia|B. C.]]"; NMC no. 232
|-
|[[File:Pink-Mt009crop-AI.jpg|alt=Osborn's caribou|180px]]<br>''R. t. osborni'' or<br>''R. a. osborni''{{efn|name="2star"|** <text missing>}}<br>(Allen, 1902)<ref name="MSW3" />{{efn|name="n1"}}<ref name="Geist" />||[[Osborn's caribou]]|| short migrations: summers in alpine forest and winters in lowland [[muskeg]]|| [[British Columbia]], Canada||males up to {{cvt|340|kg}}
|"[[Cassiar Mountains]], [[British Columbia]]; AMNH no. 15714
|-
|[[File:Peary caribou - Bathurst Island.jpg|180px]]<br />''R. t. pearyi'' or<br>''R. a. pearyi''<br>(Allen, 1902)<ref name="Banfield_1961" />||[[Peary caribou]]|| an island population that makes local movements both within and among islands ||the [[Arctic Archipelago|High Arctic islands]] (except for [[Baffin Island]]) of [[Nunavut]] and the [[Northwest Territories]], Canada<ref name="HBW" />||smallest North American subspecies: males average {{cvt|70|kg}}
|"Ellesmere Land <nowiki>[</nowiki>[[Ellesmere Island]]<nowiki>]</nowiki>, N. Lat. 79⁰"; AMNH no. 19231
|-
|''R. t. stonei'' or<br>''R. a. stonei''<br>(Allen, 1901)
|[[Stone's caribou]]
|altitudinal movements
|the mountains of southern [[Alaska]] and the southeastern [[Yukon]]
|no data
|"[[Kenai Peninsula]], [[Alaska]]"; AMNH no. 16701
|-
| rowspan="3" |''R. caribou''<br>(Gmelin, 1788)<br>''woodland caribou''
|[[File:Woodland Caribou Southern Selkirk Mountains of Idaho 2007.jpg|180px]]<br />''R. t. caribou'' or<br>''R. c. caribou''<br>(Gmelin, 1788) ||[[boreal woodland caribou]]<br /><br />|| sedentary (makes short movements to seasonal habitats) ||the boreal forests of northeastern Canada<ref name="HBW" />||males average {{cvt|180|kg}}, up to {{cvt|272|kg}}
|Type locality amended to "[[eastern Canada]]" (Miller Jr. 1912); NMC Neotype no. 4800
|-
|[[File:Caribou Rangifer tarandus caribou (47796957741).jpg|180px]]<br />''R. t. caboti'' or<br>''R. c. caboti''{{efn|name="2star"}}<br>([[Glover Morrill Allen|G. M. Allen]], 1914)<ref name="MSW3" />{{efn|name="n1"|Banfield rejected this classification in 1961. However, Geist and others considered it valid. Bangs (1896) is invalid as a taxonomic authority, as his two-page pamphlet was not published.<ref name="Harding-2022"/>}}<ref name="Geist" />||[[Labrador caribou]] or Ungava caribou|| migratory (except for the [[Torngat Mountains|Torngat Mountain]] population DU10)|| [[northern Quebec]] and northern [[Labrador]], Canada
|no data
|"Thirty miles north of [[Nachvak Fiord|Nachvak]] <nowiki>[</nowiki>[[Torngat Mountains]]<nowiki>]</nowiki>, northeast coast of Labrador", MCZ No. 15,372
|-
|[[File:Woodland Caribou, Newfoundland.jpg|180px]]<br />''R. t. terranovae'' or<br>''R. c. terranovae''<br>(Allen, 1896)<ref name="MSW3" />{{efn|name="n1"}}<ref name="Geist" />||[[Newfoundland caribou]]|| ||[[Newfoundland and Labrador|Newfoundland]], Canada ||139.6&nbsp;kg (3 adult males)<ref name="Fong1982">{{cite journal |last1=Fong |first1=D. W. |title=Immobilization of caribou with etorphine plus acepromazine |journal=The Journal of Wildlife Management |date=1982 |volume=46 |issue=2 |pages=560–562 |doi=10.2307/3808683 |jstor=3808683 |url=https://www.jstor.org/stable/3808683 |access-date=5 February 2023}}</ref>
|"[[Grand Lake (Newfoundland and Labrador)|Grand Lake]], [[Newfoundland (island)|Newfoundland]]"; AMNH 11775
|-
| rowspan="2" |''R. fennicus''<br>Lönnberg, 1909<br>''forest reindeer''
|[[File:Finnish forest reindeer (Rangifer tarandus fennicus).jpg|180px]]<br />''R. t. fennicus'' or<br>''R. f. fennicus''<br>(Lönnberg, 1909) ||[[Finnish forest reindeer]] || migratory ||northwestern [[Russia]] and [[Finland]]<ref name="HBW"/><ref name="Sami">{{cite web |title=Reindeer |work=The Sámi and their reindeer |publisher=University of Texas|location=Austin, Texas |url= http://www.utexas.edu/courses/sami/diehtu/siida/reindeer/Reindeer/reindeer_main.html|access-date=2014-01-15|archive-url=https://web.archive.org/web/20130723123401/http://www.utexas.edu/courses/sami/diehtu/siida/reindeer/Reindeer/reindeer_main.html|archive-date=2013-07-23|url-status=live}}</ref>||{{cvt|150|-|250|kg}}
|"Torne District [in [[Enontekiö]]<nowiki>]</nowiki>, Finnish [[Lapland (Finland)|Lappland]]"; NR No. 4661, Stockholm
|-
|''R. t. valentinae'' or<br>''R. f. valentinae''{{efn|name="2star"}}<br>(Flerov, 1933)<ref name="MSW3" />|| [[Siberian forest reindeer]]|| altitudinal migration || the [[Ural Mountains]], Russia and the [[Altai Mountains]], [[Mongolia]]<ref name="HBW" />||no data
|"Head of [[Chulyshman]] River, North-Eastern [[Altai Republic|Altai]], [[Siberia]]"; skin ZMASL no. 22599, skull no. 10214
|-
|''R.&nbsp;groenlandicus''<br/>(Borowsky, 1780)
|[[File:Kangerlussuaq à Sissimiut 9 Renne Groenland 2009 Expédition ACarré.JPG|180px]]<br />''R. groenlandicus'' or<br>''R. t. groenlandicus''<br>(Borowsky, 1780){{efn|Although most taxonomic authorities over the years recognized "Greenland Caribou" as a distinct subspecies, several gave the name as a subspecies of ''Cervus [Rangifer] tarandus'' for North American barren-ground caribou, ''groenlandicus'' having priority over other names. The name dates from George Edwards (1743),<ref>{{cite book |author=Edwards, George |year=1743 |title=A natural history of uncommon birds, and of some other rare and undescribed animals, quadrupedes, reptiles, fishes, insects, etc. Exhibited in two hundred and ten copper-plates, from designs copied immediately from nature, and curiously coloured after life, with a full and accurate description of each figure. Part I |place=London |doi=10.5962/bhl.title.115782}}</ref> who claimed to have seen a male specimen ("head of perfect horns...") from Greenland and said that a Captain Craycott had brought a live pair from Greenland to England in 1738.}} ||Western Greenlandic Caribou or reindeer<!--DO NOT wikilink. There is a redirect that points to this article for these titles.-->
|sedentary
|four small areas in southwestern [[Greenland]]<ref name=Poole>Poole, K.G.; Cuyler, C.; Nymand, J. (2013) Evaluation of caribou ''Rangifer tarandus groenlandicus'' survey methodology in West Greenland. Wildlife Biology 19: 225-239.</ref>
|no data
|"[[Greenland]]"{{clarify|date=November 2022}}
|-
|''R. platyrhynchus''<br/>(Vrolik, 1829)<br/>''Svalbard reindeer''
|[[File:Svalbardrein pho.jpg|180px]]<br />''R. platyrhynchus'' or<br>''R. t. platyrhynchus''<br>(Vrolik, 1829) ||[[Svalbard reindeer]] || an island population that makes local movements both within and among islands ||the [[Svalbard]] Archipelago of [[Norway]]<ref name="HBW" />||smallest of the reindeer; has extremely short legs
|"[[Svalbard|Spitzbergen]]"; Neotype no. M2625, Oslo
|-
| rowspan="4" |''R. tarandus''<br>(Linnaeus, 1758)<br>''tundra reindeer'' or ''mountain reindeer''
|''R. t. pearsoni''<br>(Lydekker, 1903)<ref name="MSW3" />||[[Novaya Zemlya reindeer]]|| an island population that makes local movements both within and among islands ||the [[Novaya Zemlya]] and [[New Siberia]] Archipelagoes of Russia and [[Wrangel Island]], Russia<ref name="HBW" />||no data
|"Island of [[Novaya Zemlya]]"; type specimen "In the possession of H. J. Pearson, Esq., [[Bramcote]], [[Nottinghamshire]], England" (Flerov, 1933).
|-
|''R. t. phylarchus''<br>(Hollister, 1912)<ref name="MSW3" />|| [[Kamchatkan reindeer]]|| ||restricted to the [[Kamchatka Peninsula]], Russia, after those reindeer west of the [[Sea of Okhotsk]] were found to actually be ''R. t. sibiricus''<ref name="HBW" /><ref name="Rozhkov-2020" />||no data
|"Southeastern [[Kamchatka Peninsula|Kamchatka]] [Kamchatka]"; USNM No. 21343
|-
|''R. t. sibiricus''<br>(Murray, 1866)<ref name="MSW3"/>|| [[Siberian tundra reindeer]]|| long-distance migrations||[[Siberia]], Russia,<ref name="HBW"/> [[Franz Josef Land]] during the [[Holocene]] from >6400–1300 [[Radiocarbon dating|cal. BP]] (from where it has been [[Local extinction|extirpated]])<ref>{{Cite journal |title=The Holocene occurrence of reindeer on Franz Josef Land, Russia |last1=Forman |first1=S. L. |last2=Lubinski |first2=D. |last3=Weihe |first3=R. R. |date=2000 |journal=The Holocene |volume=10 |issue=6 |pages=763–768 |doi=10.1191/09596830095015 |bibcode=2000Holoc..10..763F |s2cid=140183093}}</ref>||no data
|"[[Siberia]]. ...eastward of the [[Lena (river)|River Lena]]"; Type specimen of ''sibiricus'' unknown; however, Jacobi (1931) deposited a type specimen of "''asiaticus''" in the Museum of Leningrad (ZMASL), Buturlin coll. no. 240-1908
|-
|[[File:Reinbukken på frisk grønt beite. - panoramio.jpg|180px]]<br />''R. t. tarandus''<br>(Linnaeus, 1758)||[[mountain reindeer]] or Norwegian reindeer|| migratory ||the Arctic tundra of the [[Fennoscandia|Fennoscandian Peninsula]] in [[Norway]]<ref name="HBW" /><ref name="Sami" /> and the [[Eastern Region (Iceland)|Austfirðir]] in [[Iceland]] (where it has been [[Introduced species|introduced]])<ref>{{cite web |url=https://www.tinna-adventure.is/reindeer-iceland/ |title=Reindeer In Iceland|date=2017-02-13|website=Tinna Adventure|access-date=2019-09-09}}</ref>||no data
|[[Scandinavia]]
|}
Abbreviations: 
{{Div col}}
*''AMNH'' - [[American Museum of Natural History]]
*''BCPM'' - British Columbia Provincial Museum (= ''RBCM'' the [[Royal British Columbia Museum]])
*''NHMUK'' - [[British Museum]] (Natural History) (originally the ''BMNH'')
*''DMNH'' - [[Denver Museum of Nature and Science|Denver Museum of Natural History]]
*''MCZ'' - [[Museum of Comparative Zoology]]
*''MSI'' - Museum of the [[Smithsonian Institution]]
*''NMC'' - National Museum of Canada (originally the ''CGS'' Canadian Geological Survey Museum, now the ''CMN'' [[Canadian Museum of Nature]])
*''NR'' - [[Swedish Museum of Natural History|Naturhistoriska Riksmuseet]]
*''RSMNH'' - [[Royal Swedish Museum of Natural History]]
*''USNM'', - [[Smithsonian Institution|United States National Museum]]
*''ZMASL'' - [[Zoological Museum (Saint Petersburg)|Zoological Museum of the Zoological Institute of the Russian Academy of Sciences]] (formerly the Zoological Museum of the Academy of Sciences), Leningrad
{{Div col end}}
{| class="wikitable" style="text-align:center"
|+ Extinct subspecies of ''Rangifer'' 
! Subspecies !! Common name !!Division!! style="min-width:110px; width:30%" |Range!! Weight of male!! Extinct since
|-
|''R. t. eogroenlandicus''<br>(Degerbøl, 1957)<ref name="eogroenlandicus"/> ||†East Greenland caribou<br>or [[Arctic reindeer]] ||[[tundra]] ||eastern [[Greenland]]||no data||1900
|-
|''R. t. dawsoni'' or<br>''R. a. dawsoni''<br>(Thompson-Seton, 1900)<ref name=Banfield_1961 /> ||†[[Queen Charlotte Islands caribou]]<br>or Dawson's caribou ||woodland ||[[Graham Island]] of [[Haida Gwaii]] off the coast of [[British Columbia]], Canada (formerly known as the Queen Charlotte Islands)||no data||1908
|-
|''R. t. setoni'' or<br>''R. f. setoni''<br>Flerov, 1933
|†Sakhalin reindeer
|[[tundra]]
|[[Sakhalin]] in the [[Sea of Okhotsk]], Russia
|no data
|2007?
|}

The table above includes, as per the recent revision, ''R. t. caboti'' (the Labrador caribou (the Eastern Migratory population DU4)), and ''R. t. terranovae'' (the Newfoundland caribou (the Newfoundland population DU5)), which molecular analyses have shown to be of North American (i.e., woodland caribou) lineage;<ref name="mtDNA2"/> and four mountain ecotypes now known to be of distant [[Beringia]]-[[Eurasia]] lineage (see [[Reindeer#Taxonomy|Taxonomy]] above).<ref name="mtDNA2"/><ref name="Flagstad" /><ref name="Horn-2018" />

The scientific name ''Tarandus rangifer buskensis'' Millais, 1915 (the Busk Mountains reindeer) was selected as the senior synonym to ''R. t. valentinae'' Flerov, 1933, in ''[[Mammal Species of the World]]''<ref name="MSW3" /> but Russian authors<ref name="Mizin-2018b" /> do not recognize Millais and Millais' articles in a hunting travelogue, ''The Gun at Home and Abroad'',<ref name="Millais-1915">Millais, J.G. (1915) The Asiatic reindeer and elk. In: Carruthers, D.; Millais, J.G.; Wallace, H.F.; Kennion, L.C.R.L.; Barklay, F.G. (eds.) ''The Gun at Home and Abroad''. London & Counties Press Association Ltd., London, U.K., 216-223.</ref> seem short of a taxonomic authority.<ref name="Harding-2022" />

The scientific name ''groenlandicus'' is fraught with problems. Edwards (1743)<ref>Edwards, George (1743) ''A natural history of uncommon birds and of some other rare and undescribed animals quadrupedes, reptiles, fishes, insects &c exhibited in two Hundred and ten copper-plates, from designs copied immediately from nature, and curiously coloured after Life with a full and accurate description of each to which is added, a brief and general Idea of drawing and painting in water-colours; with Instructions for etching on copper with aqua fortis; likewise some thoughts on the passage of birds; and additions to many of the subjects described in this work. Vol. Part I'', London, 248 pp. {{doi|10.5962/bhl.title.115782}}</ref> illustrated and claimed to have seen a male specimen ("head of perfect horns...") from Greenland and said that a Captain Craycott had brought a live pair from Greenland to England in 1738. He named it ''Capra groenlandicus'', Greenland reindeer. Linnaeus,<ref>Linné [Linnæus], C. (1767) ''Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis Editio 12. Vol. Tomus I Editio duodecima'', Vindobonae, Upsalla, Sweden, 1,327 pp.</ref> in the 12th edition of ''Systema naturae'', gave ''grœnlandicus'' as a synonym for ''Cervus tarandus''. Borowski<ref>Borowski, G.H. (1780) ''Gemeinnüzzige Naturgeschichte des Thierreichs: darinn die merkwürdigsten und nüzlichsten Thiere in systematischer Ordnung beschrieben, und die Geschlechter in Abbildungen nach der Natur vorgestellet werden. Vol. 1 Part 4'', Gottlieb August Lange, Berlin and Stralsund, 360 pp.</ref> disagreed (and again changed the spelling), saying ''Cervus grönlandicus'' was morphologically distinct from Eurasian tundra reindeer. Baird<ref>Baird, S.F. (1859) ''Mammals of North America: the description of species based chiefly on the collections in the museum of the Smithsonian Institution''. J. B. Lippincott, Washington D.C., 764 pp.</ref> placed it under the genus ''Rangifer'' as ''R. grœnlandicus''. It went back and forth as a full species or subspecies of the barren-ground caribou (''R. arcticus'') or a subspecies of the tundra reindeer (''R. tarandus''), but always as the Greenland reindeer / caribou. Taxonomists consistently documented morphological differences between Greenland and other caribou / reindeer in cranial measurements, dentition, antler architecture, etc.<ref>Allen, G.M. (1942) Extinct and vanishing mammals of the Western Hemisphere with the marine species of all the oceans. American Committee for International Wildlife Protection Special Publication No. 11: 297-322.</ref><ref>Lydekker, R. (1898) ''Deer of all lands. a history of the family Cervidæ living and extinct''. Rowland Ward, Limited, London, U.K., 329 pp.</ref> Then Banfield (1961)<ref name="Banfield-1961" /> in his famously flawed revision, gave the name ''groenlandicus'' to all the barren-ground caribou in North America, Greenland included, because ''groenlandicus'' pre-dates Richardson's<ref>Richardson, J. (1829) ''Fauna boreali-americana; or, the zoology of the northern parts of British America; containing descriptions of the objects of natural history collected on the late northern land expeditions, under command of Captain Sir John Franklin, R.N. Vol. 1 Quadrupeds'', John Murray, London, U.K., 300 pp.</ref> ''R. arctus''. However, because genetic data shows the Greenland caribou to be the most distantly related of any caribou to all the others (genetic distance, FST = 44%,<ref name="Yannic-2013" /> whereas most cervid (deer family) species have a genetic distance of 2% to 5%<ref name="Harding-2022-3" />)--as well as behavioral and morphological differences—a recent revision returned it to species status as ''R. groenlandicus''.<ref name="Harding-2022" /> Although it has been assumed that the larger caribou that appeared in Greenland 4,000 years ago originated from [[Baffin Island]] (itself unique; see [[Reindeer#Taxonomy|Taxonomy]] above), a reconstruction of LGM glacial retreat and caribou advance (Yannic et al. 2013)<ref name="Yannic-2013" /> shows colonization by NAL lineage caribou more likely. Their PCA and tree diagrams show Greenland caribou clustering outside of the Beringian-Eurasian lineage.

The scientific name ''R. t. granti'' has a very interesting history. Allen (1902)<ref name="Allen1902" /> named it as a distinct species, ''R. granti'', from the "western end of [[Alaska Peninsula]], opposite [[Popof Island|Popoff Island]]" and noting that:<blockquote>''Rangifer granti'' is a representative of the Barren Ground group of Caribou, which includes ''R. arcticus'' of the Arctic Coast and ''R. granlandicus'' of Greenland. It is not closely related to ''R. stonei'' of the Kenai Peninsula, from which it differs not only in its very much smaller size, but in important cranial characters and in coloration. ...The external and cranial differences between ''R. granti'' and the various forms of the Woodland Caribou are so great in almost every respect that no detailed comparison is necessary. ...According to Mr. Stone, ''Rangifer granti'' inhabits the " barren land of Alaska Peninsula, ranging well up into the mountains in summer, but descending to the lower levels in winter, generally feeding on the low flat lands near the coast and in the foothills...As regards cranial characters no comparison is necessary with ''R. montanus'' or with any of the woodland forms."</blockquote>Osgood<ref name="Osgood-1909" /> and Murie (1935),<ref name="Murie-1935" /> agreeing with ''granti''{{'}}s close relationship with the barren-ground caribou, brought it under ''R. arcticus'' as a subspecies, ''R. t. granti''. Anderson (1946)<ref name="Anderson-1946" /> and Banfield (1961),<ref name="Banfield-1961" /> based on statistical analysis of cranial, dental and other characters, agreed. But Banfield (1961) also synonymized Alaska's large ''R. stonei'' with other mountain caribou of British Columbia and the Yukon as invalid subspecies of woodland caribou, then ''R. t. caribou''. This left the small, migratory barren-ground caribou of Alaska and the Yukon, including the [[Porcupine caribou]] herd, without a name, which Banfield rectified in his 1974 ''Mammals of Canada'' <ref>Banfield, Alexander William Francis. ''Mammals of Canada'' (1974). University of Toronto Press, Toronto, Ontario, 438 pp.</ref> by extending to them the name "''granti''". The late [[Valerius Geist]] (1998), in the only error in his whole illustrious career, re-analyzed Banfield's data with additional specimens found in an unpublished report he cites as "Skal, 1982", but was "not able to find diagnostic features that could segregate this form from the western barren ground type." But Skal 1982 had included specimens from the ''eastern'' end of the [[Alaska Peninsula]] and the [[Kenai Peninsula]], the range of the larger Stone's caribou. Later, geneticists comparing barren-ground caribou of Alaska with those of mainland Canada found little difference and they all became the former ''R. t. groenlandicus'' (now ''R. t. arcticus''). ''R. t. granti'' was lost in the oblivion of invalid taxonomy until Alaskan researchers sampled some small, pale caribou from the western end of the Alaska Peninsula, their range enclosing the type locality designated by Allen (1902) and found them to be genetically distinct from all other caribou in Alaska.<ref>Colson, K.E.; Mager, K.H.; Hundertmark, K.J. (2014) Reindeer introgression and the population genetics of caribou in southwestern Alaska. Journal of Heredity 105: 585-596.</ref><ref name="Mager-2014">{{Cite journal |last1=Mager |first1=Karen H. |last2=Colson |first2=Kevin E. |last3=Groves |first3=Pam |last4=Hundertmark |first4=Kris J. |date=December 2014 |title=Population structure over a broad spatial scale driven by nonanthropogenic factors in a wide-ranging migratory mammal, Alaskan caribou |journal=Molecular Ecology |volume=23 |issue=24 |pages=6045–6057 |doi=10.1111/mec.12999 |issn=0962-1083 |pmid=25403098 |bibcode=2014MolEc..23.6045M |s2cid=22614440}}</ref> Thus, ''granti'' was rediscovered, its range restricted to that originally described.

Stone's caribou (''R. t. stonei''),<ref name="Allen-1901" /> a large montane type, was described from the Kenai Peninsula (where, apparently, it was never common except in years of great abundance),<ref name="Murie-1935" /> the eastern end of the Alaska Peninsula, and mountains throughout southern and eastern Alaska.<ref name="Allen-1901">Allen, J.A. (1901) Description of a new caribou from Kenai Peninsula, Alaska. Bulletin of the American Museum of Natural History XIV: 143-148.</ref> It was placed under ''R. arcticus'' as a subspecies,<ref name="Murie-1935" /> ''R. t. stonei'', and later synonymised as noted above. The same genetic analyses mentioned above for ''R. t. granti''<ref name="Mager-2014" /> resulted in resurrecting ''R. t. stonei'' as well.<ref name="Harding-2022" />

The Sakhalin reindeer (''R. t. setoni''), endemic to [[Sakhalin]], was described as ''Rangifer tarandus setoni'' Flerov, 1933, but Banfield (1961) brought it under ''R. t. fennicus'' as a junior synonym. The wild reindeer on the island are apparently extinct, having been replaced by domestic reindeer.

Some of the ''Rangifer'' species and subspecies may be further divided by [[ecotype]] depending on several behavioral factors – predominant habitat use (northern, tundra, mountain, forest, boreal forest, forest-dwelling, woodland, woodland (boreal), woodland (migratory) or woodland (mountain), spacing (dispersed or aggregated) and migration patterns (sedentary or migratory).<ref name="j2">{{Cite journal| title=Evolving perspectives on caribou population dynamics, have we got it right yet?| doi=10.7557/2.16.4.1225| journal=[[Rangifer (journal)|Rangifer]]| volume=16| issue=Special Issue 9| year=1996| last1=Bergerud| first1=A. T.| page=95| url=https://septentrio.uit.no/index.php/rangifer/article/download/1225/1164| doi-access=free}}</ref><ref name="j1">{{cite journal |last1=Festa-Bianchet |first1=M. |last2=Ray |first2=J.C. |last3=Boutin |first3=S. |last4=Côté |first4=S.D. |last5=Gunn |first5=A. |year=2011 |title=Conservation of Caribou (''Rangifer tarandus'') in Canada: An Uncertain Future |journal=Canadian Journal of Zoology |volume=89 |issue=5 |pages=419–434 |doi=10.1139/z11-025 |display-authors=etal|doi-access=free }}</ref><ref name="b1">{{cite thesis |title=Population Structure and Hybridization of Alaskan Caribou and Reindeer: Integrating Genetics and Local Knowledge |first=Karen H. |last=Mager |degree=PhD |publisher=University of Alaska Fairbanks |location=Fairbanks, Alaska |url=http://www.uaf.edu/files/rap/Mager_16apr2012_Dissertation-1.pdf |access-date=27 December 2013 |year=2012 |archive-url=https://web.archive.org/web/20131228010933/http://www.uaf.edu/files/rap/Mager_16apr2012_Dissertation-1.pdf |archive-date=28 December 2013 |url-status=dead}}</ref> North American examples of this are the [[Torngat Mountains|Torngat Mountain]] population DU10, an ecotype of ''R. t. caboti''; a recently discovered and unnamed clade between the [[Mackenzie River]] and [[Great Bear Lake]] of Beringian-Eurasian lineage, an ecotype of ''R. t. osborni'';<ref>{{cite journal |author1=Polfus, J.L. |author2=Manseau, M. |author3=Klütsch, C.F.C. |author4=Simmons, D. |author5=Wilson, P.J. |date=2017 |title=Ancient diversification in glacial refugia leads to intraspecific diversity in a Holarctic mammal |journal=Journal of Biogeography |volume=44 |issue=2 |pages=386–396|doi=10.1111/jbi.12918 |bibcode=2017JBiog..44..386P |s2cid=90484948 |doi-access=free |hdl=1993/31986 |hdl-access=free }}</ref> the Atlantic-[[Gaspé Peninsula|Gaspésie]] population DU11, an eastern montane ecotype of the boreal woodland caribou (''R. t. caribou'');<ref>{{cite journal |author1=Pelletier, F.A. |author2=Turgeon, G. |author3=Bourret, A. |author4=Garant, D. |author5=St-Laurent, M-H. |date=2019 |title=Genetic structure and effective size of an endangered population of woodland caribou |journal=Conservation Genetics |volume=20 |issue=2 |pages=203–213|doi=10.1007/s10592-018-1124-1 |bibcode=2019ConG...20..203P |s2cid=254418477 }}</ref><ref name="Yannic-2018" /><ref>{{cite journal |author1=Frenette, J. |author2=Pelletier, F. |author3=St-Laurent, M-H |date=2020 |title=Linking habitat, predators and alternative prey to explain recruitment variations of an endangered caribou population |journal=Global Ecology and Conservation |volume=22 |at=e00920 |doi=10.1016/j.gecco.2020.e00920|s2cid=213145519 |doi-access=free |bibcode=2020GEcoC..2200920F }}</ref> the [[Baffin Island]] caribou, an ecotype of the barren-ground caribou (''R. t. arcticus'');<ref name="Jenkins-2018" /> and the [[Dolphin-Union caribou|Dolphin-Union]] "herd", another ecotype of ''R. t. arcticus''.<ref>{{cite conference |author1=Zittlau, K.A. |author2=Nagy, J. |author3=Gunn, A. |author4=Strobeck, C. |date=2009 |title=Genetic diversity among barren-ground caribou and the Porcupine caribou herds |editor1=McFarlane, K. |editor2=Gunn, A. |editor3=Strobeck, C. |book-title=Proceedings from the Caribou Genetics and Relationships Workshop, March 8–9, 2003 |pages=135–145 |publisher=Department of Natural Resources and Environment, Government of the Northwest Territories |id=Manuscript Report No. 183 |place=Edmonton, Alberta}}</ref> The last three of these likely qualify as subspecies,<ref name="Harding-2022" /> but they have not yet been formally described or named.

== Physical characteristics ==
Naming in this and following sections follows the taxonomy in the authoritative 2011 reference work ''[[Handbook of the Mammals of the World]] Vol. 2: Hoofed Mammals''.<ref name="HBW" />

=== Antlers ===
[[File:ReindeerLoosingVelvet.jpg|thumb|upright|Losing the velvet layer under which a new antler is growing, an annual process]]
In most [[Deer|cervid]] species, only males grow [[antler]]s; the reindeer is the only cervid species in which females also grow them normally.<ref name=antlers>{{cite web |title=Fun Facts about Reindeer and Caribou |website=U.S. Food and Drug Administration |date=2021-05-21 |url=https://www.fda.gov/animal-veterinary/animal-health-literacy/fun-facts-about-reindeer-and-caribou |access-date=2022-07-21}}</ref> [[Androgen]]s play an essential role in the antler formation of cervids. The antlerogenic genes in reindeer have more sensitivity to androgens in comparison with other cervids.<ref>{{cite journal |last1=Lin |first1=Zeshan |title=Biological adaptations in the Arctic cervid, the reindeer (''Rangifer tarandus'') |journal=Science |date=2019 |volume=364 |issue=6446 |pages=eaav6312 |doi=10.1126/science.aav6312 |pmid=31221829 |bibcode=2019Sci...364.6312L |title-link=doi |doi-access=free}}</ref><ref>{{cite journal |last1=Nasoori |first1=Alireza |date=2020 |title=Formation, structure, and function of extra-skeletal bones in mammals |url=https://archive.org/details/formation-structure-and-function-of-extra-skeletal-bones-in-mammals |journal=Biological Reviews |volume=95 |issue=4 |pages=986–1019 |doi=10.1111/brv.12597 |pmid=32338826 |s2cid=216556342}}</ref>

There is considerable variation among species and subspecies in the size of the antlers (e.g., they are rather small and spindly in the northernmost species and subspecies),<ref name=NorthAmerica/> but on average the bull's antlers are the second largest of any extant deer, after those of the male [[moose]]. In the largest subspecies, the antlers of large bulls can range up to {{cvt|100|cm}} in width and {{cvt|135|cm}} in beam length. They have the largest antlers relative to body size among living deer species.<ref name=antlers/> Antler size measured in number of points reflects the nutritional status of the reindeer and climate variation of its environment.<ref name="Smith1998">{{cite journal |last=Smith |first=B.E. |year=1998 |title=Antler size and winter mortality of elk: effects of environment, birth year, and parasites |journal=[[Journal of Mammalogy]] |volume=79 |issue=3 |pages=1038–1044 |jstor=1383113 |doi=10.2307/1383113 |doi-access=free}}</ref><ref name="Mahony2011">{{cite journal |journal=[[Rangifer (journal)|Rangifer]] |volume=31 |pages=21–34 |number=1 |year=2011 |title=Morphological change in Newfoundland caribou: Effects of abundance and climate |first1=Shane P. |last1=Mahoney |first2=Jackie N. |last2=Weir |first3=J. Glenn |last3=Luther |first4=James A. |last4=Schaefer |first5=Shawn F. |last5=Morrison |url=https://septentrio.uit.no/index.php/rangifer/article/view/1917/1783 |archive-url=https://web.archive.org/web/20141103235739/http://septentrio.uit.no/index.php/rangifer/article/viewFile/1917/1783 |archive-date=3 November 2014 |doi=10.7557/2.31.1.1917 |doi-access=free |url-status=live}}</ref> The number of points on male reindeer increases from birth to 5 years of age and remains relatively constant from then on.<ref name="Mahony2011"/>{{rp|24}} "In male caribou, antler mass (but not the number of tines) varies in concert with body mass."<ref name="MarkussonFolstad1997">{{cite journal|last1=Markusson|first1=Eystein|last2=Folstad|first2=Ivar|title=Reindeer antlers: visual indicators of individual quality?|journal=Oecologia|date=1 May 1997|volume=110|issue=4|pages=501–507 |doi=10.1007/s004420050186|pmid=28307241|issn=0029-8549 |bibcode=1997Oecol.110..501M|s2cid=40646035}}</ref><ref name="ThomasBarry2005">{{cite journal|last1=Thomas|first1=Don|last2=Barry |first2=Sam |title=Antler Mass of Barren-Ground Caribou Relative to Body Condition and Pregnancy Rate|journal=Arctic |date=2005 |volume=58|issue=3 |pages=241–246|jstor=40512709|citeseerx=10.1.1.541.4295}}</ref> While antlers of male woodland caribou are typically smaller than those of male barren-ground caribou, they can be over {{cvt|1|m}} across. They are flattened in cross-section, compact and relatively dense.<ref name="EC2012" /> Geist describes them as frontally emphasized, flat-beamed antlers.<ref name="Geist" /> Woodland caribou antlers are thicker and broader than those of the barren-ground caribou and their legs and heads are longer.<ref name="EC2012" /> Quebec-Labrador male caribou antlers can be significantly larger and wider than other woodland caribou. Central barren-ground male caribou antlers are perhaps the most diverse in configuration and can grow to be very high and wide. Osborn's caribou antlers are typically the most massive, with the largest circumference measurements.<ref name="Allen-1902">Allen, J.A. (1902) Description of a new caribou from northern British Columbia and remarks on ''Rangifer montanus''. Bulletin of the American Museum of Natural History XVI: 149-158.</ref>

The antlers' main beams begin at the brow "extending posterior over the shoulders and bowing so that the tips point forward. The prominent, palmate brow tines extend forward, over the face."<ref name="Virtual">{{citation |url= http://www.lcvirtualwildlife.ca/index.php/caribou |title= Caribou |work= Virtual Wildlife |location= Lethbridge, Alberta |url-status= live |archive-url= https://web.archive.org/web/20141103055205/http://www.lcvirtualwildlife.ca/index.php/caribou |archive-date= 3 November 2014}}</ref> The antlers typically have two separate groups of points, lower and upper.

Antlers begin to grow on male reindeer in March or April and on female reindeer in May or June. This process is called antlerogenesis. Antlers grow very quickly every year on the bulls. As the antlers grow, they are covered in thick [[Velvet antler|velvet]], filled with blood vessels and spongy in texture. The antler velvet of the [[barren-ground caribou]] and the [[boreal woodland caribou]] is dark chocolate brown.<ref name="NWT2012">{{citation |title=Species at Risk in the Northwest Territories 2012 |url=http://www.enr.gov.nt.ca/sites/default/files/reports/species_at_risk_in_the_nwt_2012_eng.pdf |access-date=31 October 2014 |author=GNWT |date=9 November 2023 |publisher=Government of Northwest Territories, Department of Environment and Natural Resources |isbn=978-0-7708-0196-0 |url-status=dead |archive-url=https://web.archive.org/web/20150924001254/http://www.enr.gov.nt.ca/sites/default/files/reports/species_at_risk_in_the_nwt_2012_eng.pdf |archive-date=24 September 2015}}</ref> The velvet that covers growing antlers is a highly vascularised skin. This velvet is dark brown on woodland or barren-ground caribou and slate-grey on Peary caribou and the [[Dolphin-Union caribou]] herd.<ref name="Virtual" /><ref name="GunnSeal1998">{{citation|last1=Gunn |first1=Anne |last2=Nishi |first2=J. |year=1998 |chapter= Review of information for Dolphin and Union caribou herd |title= Population and Habitat Viability Assessment Workshop for the Peary caribou (Rangifer tarandus pearyi) |series= Briefing book |editor-last1=Gunn |editor-first1=A. |editor-last2=Seal |editor-first2=U.S. |editor-last3=Miller |editor-first3=P.S. |location=Apple Valley, Minnesota |publisher=Conservation Breeding Specialist Group (SSC/UCN) |pages=1–22}}</ref><ref name="CanadaArctic2002">{{citation|year=2002a |url=http://www.arctic.uoguelph.ca/cpl/Traditional/traditional_frame.htm|title=Tuktu — Caribou |location=Guelph, Ontario|work=Canada's Arctic|access-date=17 January 2014|url-status=live|archive-url=https://web.archive.org/web/20141115024305/http://www.arctic.uoguelph.ca/cpl/Traditional/traditional_frame.htm|archive-date=15 November 2014}}</ref> Velvet lumps in March can develop into a rack measuring more than a {{cvt|1|m}} in length by August.<ref>{{cite book |title=State of Canada's forests |chapter=Woodland caribou |date=2000}}</ref>{{rp|88}}

[[File:Rangifer tarandus 04 MWNH 148.jpg|thumb|left|A ''R. tarandus'' skull]]
When the antler growth is fully grown and hardened, the velvet is shed or rubbed off. To [[Inuit]], for whom the caribou is a "culturally important [[keystone species]]", the months are named after landmarks in the caribou life cycle. For example, ''amiraijaut'' in the [[Igloolik]] region is "when velvet falls off caribou antlers."<ref name="CPL_2002_Tuktu_Caribou"/>

Male reindeer use their antlers to compete with other males during the mating season. Butler (1986) showed that the social requirements of caribou females during the rut determines the mating strategies of males and, consequently, the form of male antlers.<ref>{{cite thesis |last=Butler |first=H.E. |date=1986 |title=Mating strategies of woodland caribou: ''Rangifer tarandus caribou'' |type=Doctoral thesis |place=Calgary, Alberta |publisher=University of Calgary}}</ref> In describing woodland caribou, which have a harem-defense mating system, SARA wrote, "During the rut, males engage in frequent and furious sparring battles with their antlers. Large males with large antlers do most of the mating."<ref name="SARA2014">{{citation|url=http://www.registrelep-sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=636#biology |title=Woodland caribou boreal population – biology |date=October 2014 |access-date=3 November 2014 |publisher=SARA}}</ref> Reindeer continue to migrate until the bulls have spent their back fat.<ref name="CPL_2002_Tuktu_Caribou"/><ref>{{cite book |title=This Is My Country, What's Yours?: A Literary Atlas of Canada |date=29 May 2007 |page=496 |first=Noah |last=Richler |author-link=Noah Richler|publisher=Random House |isbn=9781551994178}}</ref><ref name="IOHP">{{cite interview|series=Igloolik Oral History Project (IOHP) |title=Interview 065 |date=1991 |location=[[Igloolik]], [[Nunavut]]}}</ref> By contrast, barren-ground caribou males tend individual females and their fights are brief and much less intense; consequently, their antlers are long, and thin, round in cross-section and less branched and are designed more for show (or sexual attraction) than fighting.

In late autumn or early winter after the rut, male reindeer lose their antlers, growing a new pair the next summer with a larger rack than the previous year. Female reindeer keep their antlers until they calve. In the [[Scandinavia]]n and [[Arctic Circle]] populations, old bulls' antlers fall off in late December, young bulls' antlers fall off in the early spring, and cows' antlers fall off in the summer.{{citation needed|date=December 2022}}

When male reindeer shed their antlers in early to mid-winter, the antlered cows acquire the highest ranks in the feeding hierarchy, gaining access to the best forage areas. These cows are healthier than those without antlers.<ref name="Thing297">{{cite journal |last1=Thing |first1=Henning |last2=Olesen |first2=Carsten Riis |last3=Aastrup |first3=Peter |title=Antler possession by west Greenland female caribou in relation to population characteristics |journal=[[Rangifer (journal)|Rangifer]] |year=1986 |volume=6 |issue=2 |page=297 |doi=10.7557/2.6.2.662 |doi-access=free }}</ref> Calves whose mothers do not have antlers are more prone to disease and have a significantly higher mortality.<ref name="Thing297" /> Cows in good nutritional condition, for example, during a mild winter with good winter range quality, may grow new antlers earlier as antler growth requires high intake.<ref name="Thing297"/>

[[File:Mammals of northern Alaska on the Arctic slope (1956) Rangifer arcticus groenlandicus skull.png|thumb|upright|right|A ''R. t. platyrhynchus'' skull]]
According to a respected [[Igloolik]] elder, Noah Piugaattuk, who was one of the last outpost camp leaders,<ref name="nunatsiaqonline">{{cite news |title=Igloolik elders win northern science award |first=Sean |last=McKibbon |newspaper=Nunatsiaq News |location=Igloolik |date=21 January 2000 |access-date=30 October 2017 |url=http://www.nunatsiaqonline.ca/archives/nunavut000131/nvt20121_10.html |quote=Elders in Igloolik were recognized with a national science award last week for their efforts in preserving traditional Inuit knowledge |archive-url=https://web.archive.org/web/20171107002305/http://www.nunatsiaqonline.ca/archives/nunavut000131/nvt20121_10.html |archive-date=7 November 2017 |url-status=dead}}</ref> caribou (''tuktu'') antlers<ref name="CPL_2002_Tuktu_Caribou">{{citation |editor=Hebert, P.D.N. |editor2=Wearing-Wilde, J. |series=Canada's Polar Life (CPL) |publisher=University of Guelph |year=2002 |title=Tuktu — Caribou |quote="Since 1986, elders in the community have worked...the Igloolik Research Centre...to record their knowledge for posterity on paper and audio tape...Noah Piugaattuk contributed 70 to 80 hours of audio tape." Use of antlers (IOHP 037); |url=http://www.arctic.uoguelph.ca/cpl/Traditional/traditional/animals/caribou.htm|access-date=30 October 2017|archive-url=https://web.archive.org/web/20171020081500/http://www.arctic.uoguelph.ca/cpl/Traditional/traditional/animals/caribou.htm |archive-date=20 October 2017 |url-status=live}}</ref>

{{blockquote|...get detached every year...Young males lose the velvet from the antlers much more quickly than female caribou even though they are not fully mature. They start to work with their antlers just as soon as the velvet starts to fall off. The young males engage in fights with their antlers towards autumn...soon after the velvet had fallen off they will be red, as they start to get bleached their colour changes...When the velvet starts to fall off the antler is red because the antler is made from blood. The antler is the blood that has hardened; in fact, the core of the antler is still bloody when the velvet starts to fall off, at least close to the base.|Elder Noah Piugaattuk of Igloolik cited in "Tuktu — Caribou" (2002) "Canada's Polar Life" }}

According to the Igloolik Oral History Project (IOHP), "Caribou antlers provided the Inuit with a myriad of implements, from [[Snow knife|snow knives]] and shovels to drying racks and seal-hunting tools. A complex set of terms describes each part of the antler and relates it to its various uses".<ref name="CPL_2002_Tuktu_Caribou"/> Currently, the larger racks of antlers are used by Inuit in [[Inuit art]] as materials for carving. [[Iqaluit]]-based Jackoposie Oopakak's 1989 carving, entitled ''Nunali'', which means "place where people live", and which is part of the permanent collection of the [[National Gallery of Canada]], includes a massive set of caribou antlers on which he has intricately carved the miniaturized world of the Inuit where "Arctic birds, caribou, polar bears, seals, and whales are interspersed with human activities of fishing, hunting, cleaning skins, stretching boots, and travelling by dog sled and kayak...from the base of the antlers to the tip of each branch".<ref name="NGC_2017_Oopakak">{{citation |url=http://cybermuse.gallery.ca/cybermuse/enthusiast/acquisitions/2003-2004/Oopakak_text_e.jsp |title=Oopakak |date=n.d.|access-date=31 October 2017 |publisher=National Gallery of Canada |url-status=live |archive-url=https://web.archive.org/web/20151012160006/http://cybermuse.gallery.ca/cybermuse/enthusiast/acquisitions/2003-2004/Oopakak_text_e.jsp |archive-date=12 October 2015 }}</ref>

=== Pelt ===
The color of the [[fur]] varies considerably, both between individuals and depending on season and species. Northern populations, which usually are relatively small, are whiter, while southern populations, which typically are relatively large, are darker. This can be seen well in North America, where the northernmost subspecies, the [[Peary caribou]], is the whitest and smallest subspecies of the continent, while the Selkirk Mountains caribou (Southern Mountain population DU9)<ref name="Allen-1902" /> is the darkest and nearly the largest,<ref name=NorthAmerica>Reid, F. (2006). ''Mammals of North America''. Peterson Field Guides. {{ISBN|978-0-395-93596-5}}</ref> only exceeded in size by Osborn's caribou (Northern Mountain population DU7).<ref name="Allen-1902" />

The [[Animal coat|coat]] has two layers of fur: a dense [[wool]]ly undercoat and a longer-haired overcoat consisting of hollow, air-filled hairs.<ref name="Bennett116">{{citation|last=Bennett |first=John|publisher=McGill-Queen's University Press|series=McGill-Queen's Native and Northern Series |date=1 June 2008|title=Uqalurait: An Oral History of Nunavut|page=116}}</ref>{{efn|According to Inuit elder Marie Kilunik of the [[Aivilingmiut]], Canadian Inuit preferred the caribou skins from caribou taken in the late summer or autumn, when their coats had thickened. They used it for winter clothing "because each hair is hollow and fills with air trapping heat."<ref>Marie Kilunik, Aivilingmiut, & Crnkovich, 1990, p. 116{{full citation needed|date=November 2022}}</ref> Fur is the primary insulation factor that allows reindeer to regulate their [[Human body temperature#Core temperature|core body temperature]] in relation to their environment, the [[Temperature gradient|thermogradient]], even if the temperature rises to {{cvt|100|F|order=flip}}.<ref name="Moote1955">{{cite journal |last=Moote |first=I. |year=1955 |title=The thermal insulation of caribou pelts |journal=Textile Research Journal |volume=25 |number =10 |pages=832–837 |doi=10.1177/004051755502501002 |s2cid=138926309}}</ref> In 1913, Dugmore noted how the woodland caribou swim so high out of the water, unlike any other mammal, because their hollow, "air-filled, quill-like hair" acts as a supporting "life jacket".<ref name="Dugmore1913">{{citation |first=Arthur Radclyffe |last=Dugmore |title=The romance of the Newfoundland caribou|page=191 |year=1913 |access-date=2 November 2014 |location=Philadelphia |publisher=Lippincott |url=https://archive.org/stream/romanceofnewfoun00dugm/romanceofnewfoun00dugm_djvu.txt}}</ref>

A darker belly color may be caused by two mutations of [[Melanocortin 1 receptor|MC1R]]. They appear to be more common in domestic reindeer herds.<ref name=Vage2014>{{cite journal |title=Two Missense Mutations in Melanocortin 1 Receptor (MC1R) Are Strongly Associated With Dark Ventral Coat Color in Reindeer (''Rangifer Tarandus'') |year=2014 |doi=10.1111/age.12187 |hdl=2164/4960| hdl-access=free| last1=Våge |first1=D. I. |last2=Nieminen |first2=M. |last3=Anderson |first3=D. G. |last4=Røed |first4=K. H. |journal=Animal Genetics |volume=45 |issue=5 |pages=750–753 |pmid=25039753}}</ref>

=== Heat exchange ===
Blood moving into the legs is cooled by blood returning to the body in a [[Countercurrent exchange|countercurrent heat exchange]] (CCHE), a highly efficient means of minimizing heat loss through the skin's surface. In the CCHE mechanism, in cold weather, blood vessels are closely knotted and intertwined with arteries to the skin and appendages that carry warm blood with veins returning to the body that carry cold blood causing the warm arterial blood to exchange heat with the cold venous blood. In this way, their legs for example are kept cool, maintaining the core body temperature nearly {{cvt|30|C-change}} higher with less heat lost to the environment. Heat is thus recycled instead of being dissipated. The "heart does not have to pump blood as rapidly in order to maintain a constant body core temperature and thus, metabolic rate." CCHE is present in animals like reindeer, fox and moose living in extreme conditions of cold or hot weather as a mechanism for retaining the heat in (or out of) the body. These are countercurrent exchange systems with the same fluid, usually blood, in a circuit, used for both directions of flow.<ref name="Rahiman2009">{{cite web |first=Mohd Hezri Fazalul |last=Rahiman |url=http://hezrif.uitm.edu.my/ese652/51%20Heat%20Exchanger%20090907d.pdf |title=Heat exchanger |year=2009 |access-date=3 November 2014 |location=Malaysia |archive-url=https://web.archive.org/web/20131205011425/http://hezrif.uitm.edu.my/ese652/51%20Heat%20Exchanger%20090907d.pdf |archive-date=5 December 2013 }}</ref>

Reindeer have specialized counter-current vascular heat exchange in their [[Nasal cavity|nasal passage]]s. Temperature gradient along the nasal [[Mucous membrane|mucosa]] is under physiological control. Incoming cold air is warmed by [[Thermoregulation|body heat]] before entering the lungs and water is condensed from the expired air and captured before the reindeer's breath is exhaled, then used to moisten dry incoming air and possibly be absorbed into the blood through the [[mucous membrane]]s.<ref name="BlixJohnsen1983">{{cite journal |last1=Blix |first1=A.S. |last2=Johnsen |first2=Helge Kreiitzer|pmid=6887057|pmc=1199219 |title=Aspects of nasal heat exchange in resting reindeer |journal=Journal of Physiology |volume=340 |year=1983 |pages=445–454 |doi=10.1113/jphysiol.1983.sp014772 }}</ref> Like [[moose]], caribou have specialized noses featuring nasal [[Nasal concha|turbinate bone]]s that dramatically increase the surface area within the [[nostril]]s.

=== Hooves ===
The reindeer has large feet with crescent-shaped cloven hooves for walking in snow or swamps. According to the Species at Risk Public Registry ([[Species at Risk Act|SARA]]), woodland<ref name="SARA2014" />
{{blockquote|"Caribou have large feet with four toes. In addition to two small ones, called "dew claws," they have two large, crescent-shaped toes that support most of their weight and serve as shovels when digging for food under snow. These large concave hooves offer stable support on wet, soggy ground and on crusty snow. The pads of the hoof change from a thick, fleshy shape in the summer to become hard and thin in the winter months, reducing the animal's exposure to the cold ground. Additional winter protection comes from the long hair between the "toes"; it covers the pads so the caribou walks only on the horny rim of the hooves."|source=SARA 2014}}

Reindeer [[Hoof|hooves]] adapt to the season: in the summer, when the tundra is soft and wet, the footpads become sponge-like and provide extra traction. In the winter, the pads shrink and tighten, exposing the rim of the hoof, which cuts into the ice and crusted snow to keep it from slipping. This also enables them to dig down (an activity known as "cratering") through the snow to their favourite food, a [[lichen]] known as reindeer lichen (''[[Cladonia rangiferina]]'').<ref>{{cite web |quote=In the winter, the fleshy pads on these toes grow longer and form a tough, hornlike rim. Caribou use these large, sharp-edged hooves to dig through the snow and uncover the lichens that sustain them in winter months. Biologists call this activity "cratering" because of the crater-like cavity the caribou's hooves leave in the snow. |page=5 |url=http://www.taiga.net/projectcaribou/pdf/allaboutcaribou.PDF |title=All About Caribou |archive-url=https://web.archive.org/web/20130706171742/http://taiga.net/projectcaribou/pdf/allaboutcaribou.PDF |archive-date=6 July 2013 |work=Project Caribou}}</ref><ref>{{cite web |title=RY.0246-32: A reindeer uses its hooves to clear away snow to reach lichen at its winter pastures. Yamal, Siberia |url=http://www.arcticphoto.co.uk/stories/avkas/ry0246-32.htm |url-status=dead |archive-url=https://web.archive.org/web/20120205212234/http://www.arcticphoto.co.uk/stories/avkas/ry0246-32.htm |archive-date=5 February 2012 |website=Arcticphoto.co.uk |access-date=16 September 2011}}</ref>

=== Size ===
The females (or "cows" as they are often called) usually measure {{cvt|162|-|205|cm}} in length and weigh {{cvt|80|-|120|kg}}.<ref name=Alaska>[http://www.adfg.alaska.gov/index.cfm?adfg=caribou.main Caribou at the Alaska Department of Fish & Game] {{webarchive|url=https://web.archive.org/web/20131230035700/http://www.adfg.alaska.gov/index.cfm?adfg=caribou.main |date=30 December 2013 }}. Adfg.state.ak.us. Retrieved on 16 September 2011.</ref> The males (or "bulls" as they are often called) are typically larger (to an extent which varies between the different species and subspecies), measuring {{cvt|180|-|214|cm}} in length and usually weighing {{cvt|159|-|182|kg}}.<ref name=Alaska/> Exceptionally large bulls have weighed as much as {{cvt|318|kg}}.<ref name=Alaska/> Weight varies drastically between the seasons, with bulls losing as much as 40% of their pre-rut weight.<ref name="Naughton2011">{{citation |title=The Natural History of Canadian Mammals |last=Naughton |first=Donna |pages=543, 562, 567 |publisher=Canadian Museum of Nature and University of Toronto Press |isbn=978-1-4426-4483-0 |year=2011 }}</ref>

The shoulder height is usually {{cvt|85|to|150|cm}}, and the tail is {{cvt|14|to|20|cm}} long.

The [[Svalbard reindeer|reindeer from Svalbard]] are the smallest of all. They are also relatively short-legged and may have a shoulder height of as little as {{cvt|80|cm}},<ref name="Svalbard">{{cite web |last1=Aanes |first1=Ronny |date=2007 |title=Svalbard reindeer |url=http://npweb.npolar.no/english/arter/svalbardrein |website=Norwegian Polar Institute |archive-url=https://web.archive.org/web/20101222190226/http://npweb.npolar.no/english/arter/svalbardrein |archive-date=22 December 2010}}</ref> thereby following [[Allen's rule]].

=== Clicking sound ===
The knees of many species and subspecies of reindeer are adapted to produce a clicking sound as they walk.<ref name=clicking>Banfield, Alexander William Francis (1966) "The caribou", pp. 25–28 in ''The Unbelievable Land''. Smith, I.N. (ed.) Ottawa: Queen's Press, cited in {{Cite journal
| pmid = 18986518
| year = 2008
| last1 = Bro-Jørgensen
| first1 = J.
| title = Knee-clicks and visual traits indicate fighting ability in eland antelopes: Multiple messages and back-up signals
| journal = BMC Biology
| volume = 6
| page = 47
| last2 = Dabelsteen
| first2 = T.
| doi = 10.1186/1741-7007-6-47
| pmc = 2596769
| doi-access = free
}}</ref> The sounds originate in the tendons of the knees and may be audible from several hundred meters away. The frequency of the knee-clicks is one of a range of signals that establish relative positions on a dominance scale among reindeer. "Specifically, loud knee-clicking is discovered to be an honest signal of body size, providing an exceptional example of the potential for non-vocal acoustic communication in mammals."<ref name=clicking/> The clicking sound made by reindeer as they walk is caused by small tendons slipping over bone protuberances (sesamoid bones) in their feet.<ref name="Shackleton2013">{{citation|title=Hoofed Mammals of British Columbia |first=David |last=Shackleton |date= May 2013 |publisher=Royal BC Museum |isbn=978-0-7726-6638-3 |orig-year=1999}}</ref><ref name="Banfield1966">{{citation|last=Banfield |first=Alexander William Francis|chapter=The caribou|title=The Unbelievable Land|editor-last=Smith|editor-first=I.N.|location=Ottawa|publisher=Queen's Press|year=1966|pages=25–28}}</ref> The sound is made when a reindeer is walking or running, occurring when the full weight of the foot is on the ground or just after it is relieved of the weight.<ref name="Dugmore1913" />

=== Eyes ===
A study by researchers from [[University College London]] in 2011 revealed that reindeer can see light with wavelengths as short as 320&nbsp;nm (i.e. in the ultraviolet range), considerably below the human threshold of 400&nbsp;nm. It is thought that this ability helps them to survive in the Arctic, because many objects that blend into the landscape in light visible to humans, such as urine and fur, produce sharp contrasts in ultraviolet.<ref name=ultraviolet>[http://www.ucl.ac.uk/news/news-articles/1105/11052502 Reindeer use UV light to survive in the wild] {{webarchive |url=https://web.archive.org/web/20111129042727/http://www.ucl.ac.uk/news/news-articles/1105/11052502 |date=29 November 2011 }}. Ucl.ac.uk (26 May 2011). Retrieved on 16 September 2011.</ref> It has been proposed that [[Corona discharge#Problems|UV flashes on power lines]] are responsible for reindeer avoiding power lines because "...in darkness these animals see power lines not as dim, passive structures but, rather, as lines of flickering light stretching across the terrain."<ref name="Tyler2014">{{cite journal |author1=Tyler, N. |author2=Stokkan, K.A. |author3=Hogg, C. |author4=Nellemann, C. |author5=Vistnes, A.I. |author6=Jeffery, G. |year=2014 |title=Ultraviolet vision and avoidance of power lines in birds and mammals |journal=Conservation Biology |volume=28 |issue=3 |pages=630–631 |doi=10.1111/cobi.12262|pmid=24621320 |pmc=4232876 |bibcode=2014ConBi..28..630T }}</ref>

In 2023, researchers studying reindeer living in [[Cairngorms National Park]], Scotland, suggested that UV visual sensitivity in reindeer helps them detect UV-absorbing lichens against a background of UV-reflecting snows.<ref>{{cite journal |last1=Dominy |first1=Nathaniel J. |last2=Hobaiter |first2=Catherine  |last3=Harris |first3=Julie M. |date=2023 |title=Reindeer and the quest for Scottish enlichenment |journal=i-Perception |volume=14 |issue=6 |pages=1–6 |doi=10.1177/20416695231218520 |pmid=38107029 |pmc=10725117 }} (note pun with [[Scottish Enlightenment]]).</ref>

The [[tapetum lucidum]] of [[Arctic reindeer]] eyes changes in color from gold in summer to blue in winter to improve their vision during times of continuous darkness, and perhaps enable them to better spot predators.<ref>{{cite journal |last1= Stokken|first1= Karl-Arne|last2= Folkow|first2= Lars|date= December 2013|title= Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer|journal= Proceedings of the Royal Society B|volume= 280|issue= 1773|page= 20132451|doi= 10.1098/rspb.2013.2451|pmid= 24174115|pmc= 3826237}}</ref>

== Biology and behaviors ==
=== Seasonal body composition ===
[[File:Svensk ren.JPG|thumb|Sweden]]

Reindeer have developed adaptations for optimal metabolic efficiency during warm months as well as for during cold months.<ref>Karasov, W.H. and Martinez del Rio, C. 2007. ''The Chemistry and Biology of Food in Physiological Ecology: How Animals Process Energy, Nutrients, and Toxins'' (pp. 49–108).</ref> The body composition of reindeer varies highly with the seasons. Of particular interest is the body composition and diet of breeding and non-breeding females between the seasons. Breeding females have more body mass than non-breeding females between the months of March and September with a difference of around {{cvt|10|kg}} more than non-breeding females. From November to December, non-breeding females have more body mass than breeding females, as non-breeding females are able to focus their energies towards storage during colder months rather than lactation and reproduction. Body masses of both breeding and non-breeding females peaks in September. During the months of March through April, breeding females have more fat mass than the non-breeding females with a difference of almost {{cvt|3|kg}}. After this, however, non-breeding females on average have a higher body fat mass than do breeding females.<ref name="Chan-McLeod AC 1999">{{cite journal | last1 = Allaye Chan-McLeod | first1 = A.C. | last2 = White | first2 = R.G. | last3 = Russell | first3 = D.E. | year = 1999 | title = Comparative body composition strategies of breeding and nonbreeding female caribou | journal = Canadian Journal of Zoology | volume = 77 | issue = 12| pages = 1901–1907 | doi=10.1139/z99-169| bibcode = 1999CaJZ...77.1901C }}</ref>

The environmental variations play a large part in reindeer nutrition, as winter nutrition is crucial to adult and neonatal survival rates.<ref>Wilmer, Pat; Stone, Graham; Johnston, Ian (2009). Environmental Physiology of Animals. Wiley. pp. 645–663. {{ISBN|9781405107242}}.</ref> Lichens are a staple during the winter months as they are a readily available food source, which reduces the reliance on stored body reserves.<ref name="Chan-McLeod AC 1999"/> Lichens are a crucial part of the reindeer diet; however, they are less prevalent in the diet of pregnant reindeer compared to non-pregnant individuals. The amount of lichen in a diet is found more in non-pregnant adult diets than pregnant individuals due to the lack of nutritional value. Although lichens are high in carbohydrates, they are lacking in essential proteins that vascular plants provide. The amount of lichen in a diet decreases in latitude, which results in nutritional stress being higher in areas with low lichen abundance.<ref name="Joly Wasser Booth 2015">{{cite journal |last1=Joly |first1=K. |last2=Wasser |first2=S. K. |last3=Booth |first3=R. |date=10 June 2015 |title=Non-Invasive Assessment of the Interrelationships of Diet, Pregnancy Rate, Group Composition, and Physiological and Nutritional Stress of Barren-Ground Caribou in Late Winter |journal=PLOS ONE |volume=10 |issue=6 |at=e0127586 |issn=1932-6203 |doi=10.1371/journal.pone.0127586 |pmid=26061003 |pmc=4464525 |bibcode=2015PLoSO..1027586J |doi-access=free}}</ref>{{rp|6}}

In a study of seasonal light-dark cycles on sleep patterns of female reindeer, researchers performed non-invasive [[electroencephalography]] (EEG) on reindeer kept in a stable at the [[University of Tromsø|UiT The Arctic University of Norway]]. The EEG recordings showed that: (1) the more time reindeer spend ruminating, the less time they spend in [[non-rapid eye movement sleep]] (NREM sleep); and (2) reindeer's brainwaves during rumination resemble the brainwaves present during NREM sleep. These results suggest that, by reducing the time requirement for NREM sleep, reindeer are able to spend more time feeding during the summer months, when food is abundant.<ref>{{cite news |last=Cell Press |date=22 December 2023 |title=Reindeer sleep while chewing their cud |url=https://www.sciencedaily.com/releases/2023/12/231222145453.htm |work=ScienceDaily |location= |access-date=December 25, 2023}}</ref><ref>{{cite journal |last1=Furrer |first1=Melanie |last2=Meier |first2=Sara A. |last3=Jan |first3=Maxime |display-authors=1 |date=December 22, 2023 |title=Reindeer in the Arctic reduce sleep need during rumination |journal=Current Biology |volume=34 |issue=2 |pages=427–433.e5 |doi=10.1016/j.cub.2023.12.012 |doi-access=free |pmid=38141616 |hdl=10037/33347 |hdl-access=free }}</ref>

=== Reproduction and life cycle ===
{{Further|Rut (mammalian reproduction)#Cervidae}}
Reindeer mate in late September to early November, and the gestation period is about 228–234 days.<ref name="Bergerud2014">{{citation |title=Caribou |first=A.T. |last=Bergerud |url=http://www.thecanadianencyclopedia.ca/en/article/caribou/ |publisher=The Canadian Encyclopedia |date=29 April 2014 |access-date=3 September 2014 |url-status=live |archive-url=https://web.archive.org/web/20141207050757/http://www.thecanadianencyclopedia.ca/en/article/caribou/ |archive-date=7 December 2014 }}</ref> During the mating season, bulls battle for access to cows. Two bulls will lock each other's antlers together and try to push each other away. The most dominant bulls can collect as many as 15–20 cows to mate with. A bull will stop eating during this time and lose much of his body fat reserves.<ref name="animalcorner.co.uk">{{cite web|url=http://www.animalcorner.co.uk/wildlife/caribou.html |title=Caribou at Animal Corner |url-status=dead |archive-url=https://web.archive.org/web/20121029063613/http://www.animalcorner.co.uk/wildlife/caribou.html |archive-date=29 October 2012 }}</ref>

To calve, "females travel to isolated, relatively predator-free areas such as islands in lakes, peatlands, lake-shores, or tundra."<ref name="SARA2014" /> As females select the habitat for the birth of their calves, they are warier than males.<ref name="Bergerud2014" /> Dugmore noted that, in their seasonal migrations, the herd follows a female for that reason.<ref name="Dugmore1913" /> Newborns weigh on average {{cvt|6|kg}}.<ref name="Naughton2011" /> In May or June, the calves are born.<ref name="Bergerud2014" /> After 45 days, the calves are able to graze and forage, but continue suckling until the following autumn when they become independent from their mothers.<ref name="animalcorner.co.uk"/>

Bulls live four years less than the cows, whose maximum longevity is about 17 years. Cows with a normal body size and who have had sufficient summer nutrition can begin breeding anytime between the ages of 1 and 3 years.<ref name="Bergerud2014" /> When a cow has undergone nutritional stress, it is possible for her to not reproduce for the year.<ref>{{Cite journal |title= Reproductive Pauses by Female Caribou |journal= Journal of Mammalogy |date= 18 February 1994 |issn= 0022-2372 |pages= 10–13 |volume= 75 |issue= 1 |doi= 10.2307/1382230 |first= Raymond D. |last= Cameron |jstor= 1382230 }}</ref> Dominant bulls, those with larger body size and antler racks, inseminate more than one cow a season.

=== Social structure, migration and range ===
[[File:Caribou using antlers.jpg|thumb|The size of the antlers plays a significant role in establishing the hierarchy in the herd<ref name=walker/>]]
Some populations of North American caribou; for example, many herds in the barren-ground caribou subspecies and some woodland caribou in [[District of Ungava|Ungava]] and northern [[Labrador]], [[Animal migration|migrate]] the farthest of any terrestrial mammal, traveling up to {{cvt|5000|km|-3}} a year, and covering {{cvt|1000000|km2|-5}}.<ref name="iucn status 19 November 2021" /><ref>[http://www.mrnf.gouv.qc.ca/english/wildlife/maps-caribou/ Caribou Migration Monitoring by Satellite Telemetry] {{webarchive|url=https://web.archive.org/web/20120514111934/http://www.mrnf.gouv.qc.ca/english/wildlife/maps-caribou/ |date=14 May 2012 }}. Mrnf.gouv.qc.ca. Retrieved on 16 September 2011.</ref> Other North American populations, the boreal woodland caribou for example, are largely sedentary.<ref name=Bergerud>{{Cite journal
| pmid = 21227095
| year = 1988
| last1 = Bergerud
| first1 = A. T.
| title = Caribou, wolves and man
| journal = Trends in Ecology & Evolution
| volume = 3
| issue = 3
| pages = 68–72
| doi = 10.1016/0169-5347(88)90019-5
| bibcode = 1988TEcoE...3...68B
}}</ref> The European populations are known to have shorter migrations. Island populations, such as the Novaya Zemlya and Svalbard reindeer and the Peary caribou, make local movements both within and among islands. Migrating reindeer can be negatively affected by [[Parasitism|parasite]] loads. Severely infected individuals are weak and probably have shortened lifespans, but parasite levels vary between populations. Infections create an effect known as [[culling]]: infected migrating animals are less likely to complete the migration.<ref name="Bartel Ober">{{cite journal|last1=Bartel|first1=Rebecca|last2=Oberhauser|first2=Karen |author-link2=Karen Oberhauser |last3=De Roode|first3=Jacob|last4=Atizer|first4=Sonya |title=Monarch butterfly migration and parasite transmission in eastern North America|journal=Ecology|date=February 2011|volume=92|issue=2 |pages=342–351|doi=10.1890/10-0489.1|pmid=21618914|pmc=7163749|bibcode=2011Ecol...92..342B |s2cid=9018584}}</ref>

Normally travelling about {{cvt|19|-|55|km}} a day while migrating, the caribou can run at speeds of {{cvt|60|-|80|km/h}}.<ref name="iucn status 19 November 2021" /> Young calves can already outrun an Olympic sprinter when only 1 day old.<ref name="Hoare 2009 45">{{cite book|last=Hoare|first=Ben|title=Animal Migration|year=2009|publisher=Natural History Museum|location=London |isbn=978-0-565-09243-6|page=45}}</ref> During the spring migration, smaller herds will group together to form larger herds of 50,000 to 500,000 animals, but during autumn migrations, the groups become smaller and the reindeer begin to mate. During winter, reindeer travel to forested areas to forage under the snow. By spring, groups leave their winter grounds to go to the calving grounds. A reindeer can swim easily and quickly, normally at about {{cvt|6.5|km/h}} but, if necessary, at {{cvt|10|km/h}} and migrating herds will not hesitate to swim across a large lake or broad river.<ref name="iucn status 19 November 2021" />

The barren-ground caribou form large herds and undertake lengthy seasonal migrations from winter feeding grounds in taiga to spring calving grounds and summer range in the tundra. The migrations of the [[Porcupine caribou|Porcupine]] herd of barren-ground caribou are among the longest of any mammal.<ref name="Eder2011" /> Greenland caribou, found in southwestern [[Greenland]], are "mixed migrators" and many individuals do not migrate; those that do migrate less than 60&nbsp;km.<ref>Raundrup, K. (2018) Movement patterns and resource selection - insights from West Greenland caribou. PhD Thesis, Denmark: Aarhus University, 115 pp.</ref> Unlike the individual-tending mating system, aggregated rutting, synchronized calving and aggregated post-calving of barren-ground caribou, Greenland caribou have a harem-defense mating system and dispersed calving and they do not aggregate.<ref name=Poole/>

Although most wild tundra reindeer migrate between their winter range in taiga and summer range in tundra, some ecotypes or herds are more or less sedentary. Novaya Zemlya reindeer (''R. t. pearsoni'') formerly wintered on the mainland and migrated across the ice to the islands for summer, but only a few now migrate.<ref name="Mizin-2018a">{{Cite journal |last1=Mizin |first1=Ivan A. |last2=Sipko |first2=Taras P. |last3=Davydov |first3=Andrey V. |last4=Gruzdev |first4=Alexander R. |date=2018 |title=The wild reindeer (''Rangifer tarandus'': Cervidae, Mammalia) on the arctic islands of Russia: a review |journal=[[Nature Conservation Research]] |volume=3 |issue=3 |doi=10.24189/ncr.2018.040 |issn=2500-008X|doi-access=free }}</ref> Finnish forest reindeer (''R. t. fennicus'') were formerly distributed in most of the coniferous forest zones south of the tree line, including some mountains, but are now spottily distributed within this zone.

{{clear left}}
As an adaptation to their Arctic environment, they have lost their [[circadian rhythm]].<ref>[https://www.wired.com/wiredscience/2010/03/arctic-reindeer-circadian-clock/ Arctic Reindeer Go Off the Circadian Clock] {{webarchive|url=https://web.archive.org/web/20131220020321/http://www.wired.com/wiredscience/2010/03/arctic-reindeer-circadian-clock/ |date=20 December 2013 }}. Wired.com (3 April 2014). Retrieved on 19 April 2014.</ref>

{{clear left}}

== Ecology ==
=== Distribution and habitat ===
[[File:20070818-0001-strolling reindeer.jpg|thumb|Sweden|alt=Walking in Sweden]]
[[File:Rennes d'élevage, mais en liberté, près de Suomussalmi. - panoramio.jpg|thumb|[[Suomussalmi]], Finland]]
[[File:Reindeer of Mongolia 02.jpg|thumb|Near [[Lake Khövsgöl]] in Mongolia]]
{{main|Reindeer distribution}}
Originally, the reindeer was found in [[Scandinavia]], [[Eastern Europe]], [[Greenland]], Russia, [[Mongolia]] and northern China north of the [[50th parallel north|50th latitude]]. In North America, it was found in Canada, [[Alaska]], and the northern [[contiguous United States]] from [[Maine]] to [[Washington (state)|Washington]]. In the 19th century, it was still present in southern [[Idaho]].<ref name="iucn status 19 November 2021" /> Even in historical times, it probably occurred naturally in [[Ireland]], and it is believed to have lived in [[Scotland]] until the 12th century, when the last reindeer were hunted in [[Orkney]].<ref name=Watson>{{cite news | last = Watson | first = Jeremy | date = 12 October 2006 | title = Sea eagle spreads its wings&nbsp;... | location = Edinburgh | newspaper = Scotland on Sunday}}</ref> During the [[Late Pleistocene]] Epoch, reindeer occurred further south in North America, such as in [[Nevada]], [[Tennessee]], and [[Alabama]],<ref>C. S. Churcher, P. W. Parmalee, G. L. Bell, and J. P. Lamb, 1989, [https://cdnsciencepub.com/doi/10.1139/z89-175 Caribou from the Late Pleistocene of northwestern Alabama], [[Canadian Journal of Zoology]]</ref> and as far south as [[Spain]] in Europe.<ref name="walker"/><ref>{{cite journal
|author1=Sommer, R. S. |author2=Nadachowski, A.
 |name-list-style=amp |title=Glacial refugia of mammals in Europe: evidence from fossil records
|journal=Mammal Rev
|year=2006
|volume=36
|issue=4
|pages=251–265
|doi=10.1111/j.1365-2907.2006.00093.x}}</ref> Though their range retreated northwards during the terminal Pleistocene, reindeer returned to Northern Europe during the [[Younger Dryas]].<ref>{{Cite journal |last1=Rivals |first1=Florent |last2=Drucker |first2=Dorothée G. |last3=Weber |first3=Mara-Julia |last4=Audouze |first4=Françoise |last5=Enloe |first5=James G. |date=6 April 2020 |title=Dietary traits and habitats of the reindeer (Rangifer tarandus) during the Late Glacial of Northern Europe |url=http://link.springer.com/10.1007/s12520-020-01052-y |journal=[[Archaeological and Anthropological Sciences]] |language=en |volume=12 |issue=5 |page=98 |doi=10.1007/s12520-020-01052-y |bibcode=2020ArAnS..12...98R |issn=1866-9557 |access-date=19 April 2024}}</ref> Today, wild reindeer have disappeared from these areas, especially from the southern parts, where it vanished almost everywhere. Large populations of wild reindeer are still found in [[Norway]], [[Finland]], [[Siberia]], Greenland, Alaska and Canada.

According to Grubb (2005), ''Rangifer'' is "circumboreal in the tundra and taiga" from "Svalbard, Norway, Finland, Russia, Alaska (USA) and Canada including most Arctic islands, and Greenland, south to northern [[Mongolia]], [[China]] (Inner Mongolia),<ref>{{cite news|title=Reindeer Ewenki: China's Last Reindeer-Herding Tribe|last=Wang|first=Wei|date=2021-01-25|work=China Today|location=Beijing, China|url=http://www.chinatoday.com.cn/ctenglish/2018/sl/202101/t20210125_800233637.html|access-date=2021-09-07}}</ref> [[Sakhalin|Sakhalin Island]], and USA (northern Idaho and Great Lakes region)." Reindeer were introduced to, and are feral in, "Iceland, [[Kerguelen Islands]], [[South Georgia|South Georgia Island]], [[Pribilof Islands]], [[St. Matthew Island]]";<ref name="MSW3" /> a free-ranging semi-domesticated herd is also present in Scotland.<ref>{{cite web|url=https://www.cairngormreindeer.co.uk/ |title=Home – The Cairngorm Reindeer Herd |publisher=Cairngormreindeer.co.uk |date= |accessdate=2022-02-16}}</ref>

There is strong regional variation in ''Rangifer'' herd size. There are large population differences among individual herds and the size of individual herds has varied greatly since 1970. The largest of all herds (in Taimyr, Russia) has varied between 400,000 and 1,000,000; the second largest herd (at the George River in Canada) has varied between 28,000 and 385,000.

While ''Rangifer'' is a widespread and numerous genus in the northern [[Holarctic realm|Holarctic]], being present in both [[tundra]] and [[taiga]] (boreal forest),<ref name=walker>{{cite book
|title=Walker's Mammals of the World
|year=1999
|publisher=[[Johns Hopkins University Press]]
|location=[[Baltimore]]
|isbn=978-0-8018-5789-8
|pages=1128–1130
|edition=6th
|volume=2
|editor=Novak, R. M.}}</ref> by 2013, many herds had "unusually low numbers" and their winter ranges in particular were smaller than they used to be.<ref name=NOAA2013 /> Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range.<ref name="Walker2009">{{cite web|url=http://news.bbc.co.uk/earth/hi/earth_news/newsid_8094000/8094036.stm |last=Walker|first=Matt |publisher=BBC |date=11 June 2009 |website=Earth News|title=Reindeer herds in global decline|archive-url=https://web.archive.org/web/20120103172521/http://news.bbc.co.uk/earth/hi/earth_news/newsid_8094000/8094036.stm |archive-date=3 January 2012 |access-date=16 September 2011|url-status=live}}</ref> This global decline is linked to [[climate change]] for northern migratory herds and industrial disturbance of habitat for non-migratory herds.<ref name="Vors-Boyce-2009">
{{cite journal |last1=Vors |first1=L. S. |last2=Boyce |first2=M. S. |year=2009 |title=Global declines of caribou and reindeer |journal=[[Global Change Biology]] |volume=15 |issue=11 |pages=2626–2633 |doi=10.1111/j.1365-2486.2009.01974.x |bibcode=2009GCBio..15.2626V |s2cid=86111815 |issn=1354-1013}}
</ref> [[Barren-ground caribou]] are susceptible to the effects of [[climate change]] due to a [[Match/mismatch|mismatch]] in the [[Phenology|phenological]] process between the availability of food during the calving period.<ref name="Joly Wasser Booth 2015"/><ref>{{Cite journal |last1=Le Corre |first1=Mael |last2=Dussault |first2=Christian |last3=Côté |first3=Steeve D. |date=8 February 2017 |title=Weather conditions and variation in timing of spring and fall migrations of migratory caribou |journal=Journal of Mammalogy |language=en |volume=98 |issue=1 |pages=260–271 |issn=0022-2372 |doi=10.1093/jmammal/gyw177 |doi-access=free}}</ref><ref>{{Cite journal |last1=Bastille-Rousseau |first1=Guillaume |last2=Schaefer |first2=James A. |last3=Lewis |first3=Keith P. |last4=Mumma |first4=Matthew A. |last5=Ellington |first5=E. Hance |last6=Rayl |first6=Nathaniel D. |last7=Mahoney |first7=Shane P. |last8=Pouliot |first8=Darren |last9=Murray |first9=Dennis L. |date=1 March 2016 |title=Phase-dependent climate–predator interactions explain three decades of variation in neonatal caribou survival |journal=Journal of Animal Ecology |language=en |volume=85 |issue=2 |pages=445–456 |doi=10.1111/1365-2656.12466 |pmid=26529139 |bibcode=2016JAnEc..85..445B |issn=1365-2656 |doi-access=free}}</ref>

In November 2016, it was reported that more than 81,000 [[reindeer in Russia]] had died as a result of climate change. Longer autumns, leading to increased amounts of freezing rain, created a few inches of ice over [[lichen]], causing many reindeer to starve to death.<ref>Gurino, Ben (16 January 2016) [https://www.washingtonpost.com/news/morning-mix/wp/2016/11/16/starvation-killed-80000-reindeer-after-unusual-arctic-rains-cut-off-the-animals-food-supply/ Starvation killed 80,000 reindeer after unusual Arctic rains cut off the animals' food supply] {{webarchive|url=https://web.archive.org/web/20161206000859/https://www.washingtonpost.com/news/morning-mix/wp/2016/11/16/starvation-killed-80000-reindeer-after-unusual-arctic-rains-cut-off-the-animals-food-supply/ |date=6 December 2016 }}. ''The Washington Post''</ref>

=== Diet ===
[[File:Reindeer licking salt from roadway.jpg|thumb|Two caribou licking salt from a roadway in [[British Columbia]]]]

Reindeer are [[ruminant]]s, having a four-chambered stomach. They mainly eat [[lichen]]s in winter, especially reindeer lichen (''[[Cladonia rangiferina]]''); they are the only large mammal able to metabolize lichen owing to specialised bacteria and protozoa in their gut.<ref name="McCloskey2011">{{citation|title=Wolves in Canada|last=McCloskey|first=Erin| publisher=Lone Pines |year=2011 |chapter=Caribou |pages=72–82 |isbn=978-1-55105-872-6}}</ref> They are also the only animals (except for some [[Gastropoda|gastropods]]) in which the enzyme [[lichenase]], which breaks down [[lichenin]] to [[glucose]], has been found.<ref>{{cite book |author=Lawrence, Eleanor |title=Henderson's Dictionary of Biology |url=https://books.google.com/books?id=ymGPfl_HDv8C&pg=PA363 |year=2008 |publisher=Pearson Benjamin Cummings Prentice Hall |isbn=978-0-321-50579-8 |pages=363–|url-status=live |archive-url=https://web.archive.org/web/20160510185334/https://books.google.com/books?id=ymGPfl_HDv8C&pg=PA363 |archive-date=10 May 2016 }}</ref> However, they also eat the leaves of [[willow]]s and [[birch]]es, as well as [[Cyperaceae|sedge]]s and [[Poaceae|grasses]].

Reindeer are [[Osteophagy|osteophagous]]; they are known to gnaw and partly consume shed antlers as a dietary supplement and in some extreme cases will cannibalise each other's antlers before shedding.<ref>{{cite web |last1=Pomeroy |first1=Ross |title=Curious Case of Reindeer Cannibalism May Have Led to Deadly Prion Disease |url=https://www.realclearscience.com/articles/2020/12/21/why_did_reindeer_in_norway_eat_each_others_antlers_653829.html |website=Real Clear Science |date=21 December 2020 |publisher=RealClearScience.com |access-date=30 June 2021}}</ref> There is also some evidence to suggest that on occasion, especially in the spring when they are nutritionally stressed,<ref>[http://www.villrein.no/Factsaboutwildreindeer/Biology/tabid/7041/Default.aspx Biology] {{webarchive|url=https://web.archive.org/web/20131029202301/http://www.villrein.no/Factsaboutwildreindeer/Biology/tabid/7041/Default.aspx |date=29 October 2013 }}. Villrein.no. Retrieved on 19 April 2014.</ref> they will feed on small rodents (such as [[lemming]]s),<ref>[https://web.archive.org/web/20111107145338/http://www.hww.ca/hww2.asp?id=91 Lemmings] at [[Hinterland Who's Who]]</ref> fish (such as the [[Arctic char]] (''Salvelinus alpinus'')), and [[Egg|bird egg]]s.<ref>Anand-Wheeler, Ingrid (2002) ''Terrestrial Mammals of Nunavut''. Nunavut Wildlife Management Board. {{ISBN|1-55325-035-4}}.</ref> Reindeer herded by the [[Chukchi people|Chukchis]] have been known to devour mushrooms enthusiastically in late summer.<ref>[http://www.folklore.ee/folklore/vol32/siimets.pdf "The Sun, the Moon and Firmament in Chukchi Mythology and on the Relations of Celestial Bodies and Sacrifice" by Ülo Siimets at 140] {{webarchive|url=https://web.archive.org/web/20080911091443/http://www.folklore.ee/folklore/vol32/siimets.pdf |date=11 September 2008 }}. (PDF) . Retrieved on 16 September 2011.</ref>

During the Arctic summer, when there is [[Midnight sun|continuous daylight]], reindeer change their sleeping pattern from one [[Circadian rhythm|synchronised with the sun]] to an [[Ultradian rhythm|ultradian]] pattern, in which they sleep when they need to digest food.<ref name = "Hickok2018">{{cite web | url= https://www.livescience.com/62870-summer-solstice-animals.html | title=How Does the Summer Solstice Affect Animals? | last= Hickok | first= K. | date= 21 June 2018 | website= [[Live Science]] | access-date= 22 June 2018}}</ref>

[[Δ13C|''δ''<sup>13</sup>C<sub>C</sub>]] values indicate reindeer living in the region around [[Biśnik Cave]] exhibited minimal ecological change during the transition from [[Marine isotope stages|MIS 3]] to MIS 2.<ref>{{Cite journal |last1=Piskorska |first1=Teresa |last2=Stefaniak |first2=Krzysztof |last3=Krajcarz |first3=Magdalena |last4=Krajcarz |first4=Maciej T. |date=2 March 2015 |title=Reindeer during the Upper Palaeolithic in Poland: Aspects of variability and paleoecology |url=https://www.sciencedirect.com/science/article/abs/pii/S1040618214005837 |journal=[[Quaternary International]] |language=en |volume=359-360 |pages=157–177 |doi=10.1016/j.quaint.2014.08.027 |bibcode=2015QuInt.359..157P |access-date=7 September 2024 |via=Elsevier Science Direct}}</ref> Dental [[mesowear]] indicates that during the Late Pleistocene, reindeer living in central Alaska had highly abrasive diets similar to wild horses.<ref>{{Cite journal |last1=Rivals |first1=Florent |last2=Mihlbachler |first2=Matthew C. |last3=Solounias |first3=Nikos |last4=Mol |first4=Dick |last5=Semprebon |first5=Gina M. |last6=de Vos |first6=John |last7=Kalthoff |first7=Daniela C. |date=1 February 2010 |title=Palaeoecology of the Mammoth Steppe fauna from the late Pleistocene of the North Sea and Alaska: Separating species preferences from geographic influence in paleoecological dental wear analysis |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018209005318 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=286 |issue=1–2 |pages=42–54 |doi=10.1016/j.palaeo.2009.12.002 |bibcode=2010PPP...286...42R |access-date=7 September 2024 |via=Elsevier Science Direct}}</ref>
{{clear left}}

=== Predators ===
[[File:Reindeer-on-the-rocks.jpg|thumb|Standing on snow to avoid bloodsucking insects|alt=A herd standing on snow to avoid bloodsucking insects]]

A variety of predators prey heavily on reindeer, including overhunting by people in some areas, which contributes to the decline of populations.<ref name="SARA2014" />

[[Golden eagle]]s prey on calves and are the most prolific hunter on the calving grounds.<ref>Walker, Matt. (20 October 2009) [http://news.bbc.co.uk/earth/hi/earth_news/newsid_8314000/8314558.stm Eagles filmed hunting reindeer] {{webarchive|url=https://web.archive.org/web/20111201065826/http://news.bbc.co.uk/earth/hi/earth_news/newsid_8314000/8314558.stm |date=1 December 2011 }}. BBC News. Retrieved on 16 September 2011.</ref> [[Wolverine]]s will take newborn calves or birthing cows, as well as (less commonly) infirm adults.

[[Brown bear]]s and [[polar bear]]s prey on reindeer of all ages but, like wolverines, are most likely to attack weaker animals, such as calves and sick reindeer, since healthy adult reindeer can usually outpace a bear. The gray [[wolf]] is the most effective natural predator of adult reindeer and sometimes takes large numbers, especially during the winter. Some gray wolf packs, as well as individual [[grizzly bear]]s in Canada, may follow and live off of a particular reindeer herd year-round.<ref name="j2" /><ref name="McLoughlin2003">{{cite journal |last1=McLoughlin |first1=P.D. |last2=Dzus |first2=E. |last3=Wynes |first3=B. |last4=Boutin |first4=Stan |year=2003 |title=Declines in populations of woodland caribou |journal=Journal of Wildlife Management |volume=67 |issue=4 |pages=755–761|doi= 10.2307/3802682 |jstor=3802682}}</ref>

In 2020, scientists on [[Svalbard]] witnessed, and were able to film for the first time, a polar bear attack reindeer, driving one into the ocean, where the polar bear caught up with and killed it.<ref name="Chapman_10/22/2021">{{cite web | last=Chapman | first=Andrew | date=October 22, 2021 | title=Polar bear hunting a reindeer caught on tape for first time. Unusual behavior had been assumed, but never clearly seen | website=[[Science (journal)|Science]] | url=https://www.science.org/content/article/polar-bear-hunting-reindeer-caught-tape-first-time | access-date=October 26, 2021 }}</ref> The same bear successfully repeated this hunting technique the next day. On Svalbard, reindeer remains account for 27.3% in polar bear scats, suggesting that they "may be a significant part of the polar bear's diet in that area".<ref name="Stempniewicz_Kulaszewicz_Aars_10/12/2021">{{cite journal | last1=Stempniewicz | first1=Lech | last2=Kulaszewicz | first2=Izabela | last3=Aars | first3=Jon | title=Yes, they can: polar bears ''Ursus maritimus'' successfully hunt Svalbard reindeer ''Rangifer tarandus platyrhynchus'' | journal=Polar Biology | publisher=Springer Science and Business Media LLC | volume=44 | issue=11 | date=October 12, 2021 | issn=0722-4060 | doi=10.1007/s00300-021-02954-w | pages=2199–2206| bibcode=2021PoBio..44.2199S | s2cid=241470816 | doi-access=free }}</ref>

Additionally, as carrion, reindeer may be scavenged opportunistically by [[Red fox|red]] and [[Arctic fox]]es, various species of [[eagle]]s, [[hawk]]s and [[falcon]]s, and [[common raven]]s.

Bloodsucking insects, such as [[mosquito]]es, [[Black fly|black flies]], and especially the reindeer warble fly or reindeer botfly (''[[Hypoderma tarandi]]'') and the reindeer nose botfly (''[[Cephenemyia trompe]]''),<ref name="Vors-Boyce-2009"/><ref name="Cooper-2014">{{cite journal |last=Cooper |first=Elisabeth J. |title=Warmer Shorter Winters Disrupt Arctic Terrestrial Ecosystems |journal=[[Annual Review of Ecology, Evolution, and Systematics]] |publisher=[[Annual Reviews (publisher)|Annual Reviews]] |volume=45 |issue=1 |date=2014-11-23 |issn=1543-592X |doi=10.1146/annurev-ecolsys-120213-091620 |pages=271–295|doi-access=free }}</ref> are a plague to reindeer during the summer and can cause enough stress to inhibit feeding and calving behaviors.<ref>{{cite web |url= http://www.learner.org/jnorth/tm/caribou/Predators.html |title=Caribou Foes: Natural Predators in the Wilderness |website=Learner.org|access-date=16 September 2011|archive-url=https://web.archive.org/web/20110824104908/http://www.learner.org/jnorth/tm/caribou/Predators.html |archive-date=24 August 2011 |url-status=live}}</ref> An adult reindeer will lose perhaps about {{cvt|1|L}} of blood to biting insects for every week it spends in the tundra.<ref name="Hoare 2009 45"/> The population numbers of some of these predators is influenced by the migration of reindeer.{{Citation needed|date=May 2012}} Tormenting insects keep caribou on the move, searching for windy areas like hilltops and mountain ridges, rock reefs, lakeshore and forest openings, or snow patches that offer respite from the buzzing horde. Gathering in large herds is another strategy that caribou use to block insects.<ref>{{cite web |url=http://www.taiga.net/projectcaribou/pdf/allaboutcaribou.PDF |title=An Educator's Guide to Wild Caribou of North America |publisher=Project Caribou |access-date=17 January 2014 |url-status=dead |archive-url=https://web.archive.org/web/20130706171742/http://taiga.net/projectcaribou/pdf/allaboutcaribou.PDF |archive-date=6 July 2013}}</ref>

Reindeer are good swimmers and, in one case, the entire body of a reindeer was found in the stomach of a [[Greenland shark]] (''Somniosus microcephalus''), a species found in the far North [[Atlantic]].<ref>{{cite web|url=http://www.postmodern.com/~fi/sharkpics/ellis/greenlan.htm |title=Greenland Shark (''Somniosus microcephalus'') |website=Postmodern.com |access-date=16 September 2011 |archive-url=https://web.archive.org/web/20120510184324/http://www.postmodern.com/~fi/sharkpics/ellis/greenlan.htm |archive-date=10 May 2012 |url-status=dead}}</ref>

=== Other threats ===
[[White-tailed deer]] (''Odocoileus virginianus'') commonly carry meningeal worm or brainworm (''[[Parelaphostrongylus tenuis]]''), a [[nematode]] parasite that causes reindeer, [[moose]] (''Alces alces''), [[elk]] (''Cervus canadensis''), and [[mule deer]] (''Odocoileus hemionus'') to develop fatal neurological symptoms<ref name="duffy-wildlife-diseases">{{cite journal |last=Duffy |first=Michael S. |author2=Nathan J. Keppie |author3=Michael D. B. Burt |title=Meningeal Worm is a Long-lived Parasitic Nematode in White-tailed Deer |journal=Journal of Wildlife Diseases |year=2002 |volume=38 |issue=2 |pages=448–452 |doi=10.7589/0090-3558-38.2.448 |pmid=12038147 |s2cid=39879199}}</ref><ref>{{cite book |last=Smith |first=M.C. |display-authors=etal |title=Goat Medicine |publisher=Lea & Febiger |year=1994 |volume=150}}</ref><ref name="vet.utk.edu">{{cite web |url=http://www.vet.utk.edu/news/story/brain-worm-%28meningeal-worm%29-infestation-in-llamas-and-alpacas.html |title="Brain Worm" (Meningeal Worm) Infestation in Llamas and Alpacas |publisher=University of Tennessee |access-date=14 November 2013|url-status=live |archive-url=https://web.archive.org/web/20131021025732/http://www.vet.utk.edu/news/story/brain-worm-%28meningeal-worm%29-infestation-in-llamas-and-alpacas.html |archive-date=21 October 2013}}</ref> which include a loss of fear of humans. White-tailed deer that carry this worm are partially immune to it.<ref name="Naughton2011" />

Changes in climate and habitat beginning in the 20th century have expanded range overlap between white-tailed deer and caribou, increasing the frequency of infection within the reindeer population. This increase in infection is a concern for wildlife managers. Human activities, such as "clear-cutting forestry practices, forest fires, and the clearing for agriculture, roadways, railways, and power lines," favor the conversion of habitats into the preferred habitat of the white-tailed deer – "open forest interspersed with meadows, clearings, grasslands, and riparian flatlands."<ref name="Naughton2011" /> Towards the end of the Soviet Union, there was increasingly open admission from the Soviet government that reindeer numbers were being negatively affected by human activity, and that this must be remediated especially by supporting reindeer breeding by native herders.<ref name="Astakhov-Khaitun-Subbotin-1989">{{cite journal | last1=Astakhov | first1=Alexander S. | last2=Khaitun | first2=A. D. | last3=Subbotin | first3=G. E. | title=Socioeconomic Aspects of Oil and Gas Development in West Siberia | journal=[[Annual Review of Energy and the Environment]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=14 | issue=1 | year=1989 | issn=0362-1626 | doi=10.1146/annurev.eg.14.110189.001001 | pages=117–130 | s2cid=154741203| doi-access=free }}</ref>

== Conservation ==
=== Current status ===
[[File:Pair of caribou grazing.jpg|thumb|Grazing pair in the [[Kenai National Wildlife Refuge]]]]
According to the [[International Union for Conservation of Nature|IUCN]], ''Rangifer tarandus'', as a species, is not endangered because of its overall large population and its widespread range, but, as of 2015, the IUCN has classified the reindeer as [[Vulnerable species|Vulnerable]] due to an observed population decline of 40% over the last +25 years.<ref name="iucn status 19 November 2021" /> Some reindeer [[species]] and [[subspecies]] are rare and three subspecies have already become [[Extinction|extinct]].<ref name="HighArctic" /><ref name=dawsoni />

In North America, the Queen Charlotte Islands caribou<ref name="COSEWIC2013">{{citation|url=http://www.cosewic.gc.ca/eng/sct4/result_e.cfm?SSGbox=All|year=2004|work=COSEWIC|institution=Committee on the Status of Endangered Wildlife in Canada|access-date=16 January 2014|title=Subcommittees|url-status=dead|archive-url=https://web.archive.org/web/20140201231054/http://www.cosewic.gc.ca/eng/sct4/result_e.cfm?SSGbox=All|archive-date=1 February 2014}}</ref><ref name=dawsoni>{{cite journal|author1=S. A. Byun |author2=B. F. Koop |author3=T. E. Reimchen |title=Evolution of the Dawson caribou (''Rangifer tarandus dawsoni'')|journal= Can. J. Zool.|volume= 80|issue=5|pages= 956–960|year=2002|doi=10.1139/z02-062|bibcode=2002CaJZ...80..956B |s2cid=4950388 }}</ref><ref name="HighArctic"/> and the East Greenland caribou both became extinct in the early 20th century, the Peary caribou is designated as Endangered, the boreal woodland caribou is designated as Threatened and some individual populations are endangered as well. While the barren-ground caribou is not designated as Threatened, many individual herds — including some of the largest — are declining and there is much concern at the local level.<ref name="RussellGunn2013">{{citation|title=Migratory Tundra ''Rangifer''|first1=Don E.|last1=Russell|first2=A.|last2=Gunn|institution=NOAA Arctic Research Program|date=20 November 2013|access-date=14 January 2014|url=http://www.arctic.noaa.gov/reportcard/caribou_reindeer.html|series=Annual Arctic Report Card|url-status=live|archive-url=https://web.archive.org/web/20140121105443/http://www.arctic.noaa.gov/reportcard/caribou_reindeer.html|archive-date=21 January 2014}}</ref> Grant's caribou, a small, pale subspecies endemic to the western end of the [[Alaska Peninsula]] and the adjacent islands,<ref name="Allen1902" /> has not been assessed as to its conservation status.

The status of the [[Dolphin-Union caribou|Dolphin-Union]] "herd" was upgraded to Endangered in 2017.<ref>COSEWIC (2017) COSEWIC assessment and status report on the caribou (''Rangifer tarandus'') Dolphin and Union population in Canada (http://www.registrelep-sararegistry.gc.ca/default.asp?lang=en&n=24F7211B-1 ). Committee on the Status of Endangered Wildlife in Canada, Ottawa, Ontario, 51 pp.</ref> In NWT, Dolphin-Union caribou were listed as Special Concern under the NWT Species at Risk (NWT) Act (2013).

Both the Selkirk Mountains caribou (Southern Mountain population DU9) and the Rocky Mountain caribou (Central Mountain population DU8) are classified as Endangered in Canada in regions such as southeastern British Columbia at the [[Canada–United States border]], along the [[Columbia River|Columbia]] and [[Kootenay River|Kootenay]] Rivers and around [[Kootenay Lake]]. Rocky Mountain caribou are extirpated from Banff National Park,<ref>Hebblewhite, M.; White, C.A.; Musiani, M. (2010) Revisiting extinction in National Parks: mountain caribou in Banff. Conservation Biology 24: 341-344.</ref> but a small population remains in Jasper National Park and in mountain ranges to the northwest into British Columbia. Montane caribou are now considered [[Local extinction|extirpated]] in the [[contiguous United States]], including [[Washington (state)|Washington]] and [[Idaho]]. Osborn's caribou (Northern Mountain population DU7) is classified as Threatened in Canada.

In Eurasia, the Sakhalin reindeer is [[Extinction|extinct]] (and has been replaced by domestic reindeer) and reindeer on most of the Novaya Zemlya islands have also been replaced by domestic reindeer, although some wild reindeer still persist on the northern islands.<ref name="Mizin-2018a" /> Many Siberian tundra reindeer herds have declined, some dangerously, but the Taymir herd remains strong and in total about 940,000 wild Siberian tundra reindeer were estimated in 2010.<ref name="Mizin-2018b" />

There is strong regional variation in ''Rangifer'' herd size. By 2013, many caribou herds in North America had "unusually low numbers" and their winter ranges in particular were smaller than they used to be.<ref name="RussellGunn2013" /> Caribou numbers have fluctuated historically, but many herds are in decline across their range.<ref name="Walker2009"/> There are many factors contributing to the decline in numbers.<ref name="Vors-Boyce-2009"/>

=== Boreal woodland caribou===
Ongoing human development of their [[habitat]] has caused populations of boreal woodland caribou to disappear from their original southern range. In particular, boreal woodland caribou were [[Local extinction|extirpated]] in many areas of eastern North America in the beginning of the 20th century. Professor Marco Musiani of the University of Calgary said in a statement that "The woodland caribou is already an endangered subspecies in southern Canada and the United States...[The] warming of the planet means the disappearance of their critical habitat in these regions. Caribou need undisturbed lichen-rich environments and these types of habitats are disappearing."<ref>{{cite magazine |url=http://www.smithsonianmag.com/science-nature/six-ways-climate-change-is-waging-war-on-christmas-180948064/?no-ist |magazine=Smithsonian Magazine |title=Six Ways Climate Change Is Waging War on Christmas |first=Sarah |last=Zielinski |date=16 December 2013 |access-date=16 August 2014}}</ref>

Boreal woodland caribou were designated as [[Threatened species|Threatened]] in 2002 by the [[Committee on the Status of Endangered Wildlife in Canada]], (COSEWIC).<ref name="COSEWIC2011DUReport" /> Environment Canada reported in 2011 that there were approximately 34 000 boreal woodland caribou in 51 ranges remaining in Canada ([[Environment and Climate Change Canada|Environment Canada]], 2011b).<ref name="EC2012" /> "According to Geist, the "woodland caribou is highly endangered throughout its distribution right into Ontario."<ref name="MSW3" />

In 2002, the Atlantic-[[Gaspé Peninsula|Gaspésie]] population DU11 of the boreal woodland caribou was designated as Endangered by COSEWIC. The small isolated population of 200 animals was at risk from predation and habitat loss.

=== Peary caribou===
In 1991, COSEWIC assigned "endangered status" to the [[Banks Island]] and High Arctic populations of the [[Peary caribou]]. The Low Arctic population of the Peary caribou was designated as Threatened. In 2004, all three were designated as "endangered."<ref name="COSEWIC2013" /> In 2015, COSEWIC returned the status to Threatened.

== Relationship with humans ==
{{See also|Reindeer in Siberian shamanism|Reindeer hunting in Greenland}}
[[File:Reindeer pulling sleigh, Russia.jpg|thumb|Pulling a sled in Russia|alt=A team pulling a sled in Russia]]

Arctic peoples have depended on caribou for food, clothing, and shelter. European prehistoric cave paintings represent both tundra and forest forms, the latter either the [[Finnish forest reindeer]] or the narrow-nosed reindeer, an eastern Siberia forest form.<ref name="Geist1998" /> Canadian examples include the [[Caribou Inuit]], the inland-dwelling [[Inuit]] of the [[Kivalliq Region]] in [[northern Canada]], the Caribou Clan in the Yukon, the [[Iñupiat]], the [[Inuvialuit]], the [[Hän]], the [[Northern Tutchone]], and the [[Gwichʼin]] (who followed the [[Porcupine caribou]] herd for millennia). Hunting wild reindeer and herding of semi-domesticated reindeer are important to several Arctic and sub-Arctic peoples such as the [[Dukha people|Duhalar]] for meat, {{Ill|Reindeer hide|lt=hides|de|Rentierfell}}, antlers, {{Ill|Reindeer milk|lt=milk|ru|Оленье молоко}}, and transportation.<ref name="Burch">"In North America and Eurasia the species has long been an important resource — in many areas ''the'' most important resource — for peoples inhabiting the northern boreal forest and tundra regions." (Banfield 1961:170; Kurtén 1968:170) {{cite journal |author=Ernest S. Burch Jr. |jstor=278435 |title=The Caribou/Wild Reindeer as a Human Resource |journal=American Antiquity |volume=37 |issue=3 |year=1972 |pages=339–368 |doi=10.2307/278435 |s2cid=161921691}}</ref>

Reindeer have been domesticated at least two and probably three times, in each case from wild Eurasian tundra reindeer after the [[Last Glacial Maximum|Last Glacial Maximum (LGM)]].<ref>{{cite journal |author1=Røed, K.H. |author2=Flagstad, O. |author3=Nieminen, M. |author4=Holand, O. |author5=Dwyer, M.J. |author6=Rov, N. |author7=Vila, C. |date=2008 |title=Genetic analyses reveal independent domestication origins of Eurasian reindeer |journal=[[Proceedings of the Royal Society B: Biological Sciences]] |volume=275 |issue=1645 |pages=1849–1855 |doi=10.1098/rspb.2008.0332|pmid=18460427 |pmc=2593925 }}</ref><ref name="Weldenegodguad-2020" /> Recognizably different domestic reindeer breeds include those of the Evenk, Even, and Chukotka-Khargin people of Yakutia and the Nenets breed from the Nenets Autonomous district and Murmansk region;<ref>{{cite journal |author1=Svishcheva, G. |author2=Babayan, O. |author3=Sipko, T. |author4=Kashtanov, S. |author5=Kholodova, M. |author6=Stolpovsky, Y. |date=2022 |title=Genetic differentiation between coexisting wild and domestic Reindeer (''Rangifer tarandus'' L. 1758) in Northern Eurasia |journal=[[Genetic Resources]] |volume=3 |issue=6 |pages=1–14 |doi=10.46265/genresj.UYML5006 |url=https://www.genresj.org/index.php/grj/article/view/genresj.UYML5006/125|access-date=2023-05-24|doi-access=free }}</ref> the Tuvans, Todzhans, Tofa (Tofalars in the Irkutsk Region), the Soyots (the Republic of Buryatia), and the Dukha (also known as Tsaatan, the Khubsugul) in the Province of Mongolia.<ref>{{cite journal |author1=Kharzinova, V.R. |author2=Dotsev, A.V. |author3=Solovieva, A.D. |author4=Shimit, L.D. |author5=Kochkarev, A.P. |author6=Reyer, H. |author7=Zinovieva, N.A. |date=2022 |title=Genome-Wide SNP Analysis Reveals the Genetic Diversity and Population Structure of the Domestic Reindeer Population (''Rangifer tarandus'') Inhabiting the Indigenous Tofalar Lands of Southern Siberia |journal=[[Diversity (journal)|Diversity]] |volume=14 |issue=11 |page=900 |doi=10.3390/d14110900|doi-access=free }}</ref> The [[Sámi people|Sámi]] ([[Sápmi]]) have also depended on reindeer herding and fishing for centuries.<ref name="AtlasIV">{{citation |year=1971 |title=Atlas of Murmansk Oblast}}</ref>{{rp|IV}}<ref name="ATSBook16">{{citation |title=Administrative-Territorial Divisions of Murmansk Oblast}}</ref>{{rp|16}} In [[Sápmi]], reindeer are used to pull a [[pulk]], a Nordic sled.<ref name="Sami"/>

In traditional British and United States [[Christmas]] legend, [[Santa Claus's reindeer]] pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve.

The reindeer has an important economic role for all [[circumpolar peoples]], including the Sámi, the Swedes, the Norwegians, the Finns and the Northwestern Russians in Europe, the [[Nenets people|Nenets]], the [[Khanty]], the [[Evenks]], the [[Yukaghir people|Yukaghirs]], the [[Chukchi people|Chukchi]] and the [[Koryaks]] in Asia and the [[Inuit]] in North America. It is believed that domestication started between the [[Bronze Age|Bronze]] and [[Iron Age]]s. Siberian reindeer owners also use the reindeer to ride on (Siberian reindeer are larger than their Scandinavian relatives). For breeders, a single owner may own hundreds or even thousands of animals. The numbers of Russian and Scandinavian reindeer herders have been drastically reduced since 1990. The sale of [[fur]] and meat is an important source of income. Reindeer were introduced into Alaska near the end of the 19th century; they interbred with the native caribou subspecies there. Reindeer herders on the [[Seward Peninsula]] have experienced significant losses to their herds from animals (such as wolves) following the wild caribou during their migrations.{{Citation needed|date=May 2012}}

Reindeer meat is popular in the Scandinavian countries. Reindeer [[meatball]]s are sold canned. [[Sautéed reindeer]] is the best-known dish in Sápmi. In Alaska and Finland, reindeer [[sausage]] is sold in supermarkets and [[grocery store]]s. Reindeer meat is very tender and lean. It can be prepared fresh, but also dried, [[Salt-cured meat|salted]] and hot- and cold-[[Smoked meat|smoked]]. In addition to meat, almost all of the internal organs of reindeer can be eaten, some being traditional dishes.<ref>[http://www.saunalahti.fi/~marian1/gourmet/reindeer.htm Reindeer] {{webarchive |url=https://web.archive.org/web/20111104180414/http://www.saunalahti.fi/%7Emarian1/gourmet/reindeer.htm |date=4 November 2011}}. Saunalahti.fi. Retrieved on 16 September 2011.</ref> Furthermore, ''Lapin Poron liha'', fresh reindeer meat completely produced and packed in [[Lapland (Finland)|Finnish Sápmi]], is protected in Europe with [[Geographical indications and traditional specialities in the European Union#Protected designation of origin (PDO)|PDO]] classification.<ref name="60N">[http://60north.mmm.fi/news?&article=13673753&section=05 Lapland Reindeer meat protected in the EU] {{webarchive |url=https://web.archive.org/web/20091207090514/http://60north.mmm.fi/news?&article=13673753&section=05 |date=7 December 2009}}. North Magazine (Accessed 19 July 2010)</ref><ref name="DOOR">[http://ec.europa.eu/agriculture/quality/door/list.html European Commission PDO/PGI list] {{webarchive |url=https://web.archive.org/web/20100819142342/http://ec.europa.eu/agriculture/quality/door/list.html |date=19 August 2010}}. (Accessed 19 July 2010)</ref>

Reindeer antlers are powdered and sold as an [[aphrodisiac]], or as a nutritional or medicinal supplement, to Asian markets.

The blood of the caribou was supposedly mixed with alcohol as drink by hunters and loggers in colonial Quebec to counter the cold. This drink is now enjoyed without the blood as a wine and whiskey drink known as ''[[Caribou (drink)|Caribou]]''.<ref>{{cite web |first=Sébastien |last=Mieusset |title=Le "Temps des sucres" au Québec |url=http://www.cuisine.tv/cid6799/le-temps-des-sucres-au-quebec.html |url-status=dead |archive-url=https://web.archive.org/web/20090501072919/http://www.cuisine.tv/cid6799/le-temps-des-sucres-au-quebec.html |archive-date=1 May 2009 }}</ref><ref name=ass>{{cite web|title=Quebec's Carnaval is worth freezing your a** off for |first=Julie |last=Ovenell-Carter |date=6 February 2009 |publisher=theseboots.travel |url=http://theseboots.travel/2009/02/06/worth-repeating-quebecs-carnaval-is-worth-freezing-your-a-off-for/ |url-status=dead |archive-url=https://web.archive.org/web/20120303133943/http://theseboots.travel/2009/02/06/worth-repeating-quebecs-carnaval-is-worth-freezing-your-a-off-for/ |archive-date=3 March 2012 }}</ref>

=== Indigenous North Americans ===
{{missing information|section|US government intervention to introduce herding in the form of [[Alaska Reindeer Service]]; Canadian purchase from Alaska|date=March 2023}} 
Caribou are still hunted in Greenland and in North America. In the traditional lifestyles of some of Canada's [[Inuit]] peoples and northern [[First Nations in Canada|First Nations]] peoples, [[Alaska Natives]], and the [[Kalaallit]] of Greenland, caribou is an important source of food, clothing, shelter and tools.

[[File:Early 20th Century Inuit parka (UBC).jpg|thumb|upright|An early 20th century Inuit [[parka]] made of caribou skin]]

The [[Caribou Inuit]] are inland-dwelling Inuit in present-day [[Nunavut]]'s [[Kivalliq Region]] (formerly the [[Keewatin Region, Northwest Territories]]), Canada. They subsisted on caribou year-round, eating dried caribou meat in the winter. The [[Ahiarmiut]] are Caribou Inuit that followed the Qamanirjuaq barren-ground caribou herd.<ref>{{Cite magazine |title=History & Culture – Qamanirjuwhat? |url=http://www.polarbearalley.com/Assets/pages10-11.pdf |magazine=Hudson Bay Post |date=October 2007 |volume=3 |pages=10–11 |access-date=12 February 2008 |issue=2 |archive-url=https://web.archive.org/web/20080216073833/http://www.polarbearalley.com/Assets/pages10-11.pdf |archive-date=16 February 2008 }}</ref>

There is an Inuit saying in the [[Kivalliq Region]]:<ref name="McCloskey2011" />

{{blockquote|The caribou feeds the wolf, but it is the wolf who keeps the caribou strong.|Kivalliq region}}

Elder Chief of Koyukuk and chair for the Western Arctic Caribou Herd Working Group Benedict Jones, or Kʼughtoʼoodenoolʼoʼ, represents the Middle [[Yukon River]], Alaska. His grandmother was a member of the Caribou Clan, who travelled with the caribou as a means to survive. In 1939, they were living their traditional lifestyle at one of their hunting camps in Koyukuk near the location of what is now the [[Koyukuk National Wildlife Refuge]]. His grandmother made a pair of new mukluks in one day. Kʼughtoʼoodenoolʼoʼ recounted a story told by an elder, who "worked on the steamboats during the [[gold rush]] days out on the Yukon." In late August, the caribou migrated from the Alaska Range up north to [[Huslia, Alaska|Huslia]], Koyukuk and the [[Tanana, Alaska|Tanana]] area. One year when the steamboat was unable to continue, they ran into a caribou herd estimated to number 1 million animals, migrating across the Yukon. "They tied up for seven days waiting for the caribou to cross. They ran out of wood for the steamboats, and had to go back down 40 miles to the wood pile to pick up some more wood. On the tenth day, they came back and they said there was still caribou going across the river night and day."<ref name="WACHWG2012">{{citation|title=Caribou Census Complete: 325,000 animals|date=August 2012 |url=http://westernarcticcaribou.org/wp-content/uploads/2012/08/CT2012_FINAL_0628_lowresolution.pdf |newspaper=Caribou Trails: News from the Western Arctic Caribou Herd Working Group|archive-url=https://web.archive.org/web/20120830105109/http://westernarcticcaribou.org/wp-content/uploads/2012/08/CT2012_FINAL_0628_lowresolution.pdf|location=Nome, Alaska|access-date=14 January 2014|archive-date=30 August 2012|institution=Western Arctic Caribou Herd Working Group|agency=Alaska Department of Fish and Game|url-status=live}}</ref>

The [[Gwichʼin]], an indigenous people of northwestern Canada and northeastern Alaska, have been dependent on the international migratory [[Porcupine caribou]] herd for millennia.<ref name="Chapinetal_2009">{{cite book |title=Principles of Ecosystem Stewardship: Resilience-Based Natural Resource |editor=F. Stuart Chapin III |editor2=Gary P. Kofinas |editor3=Carl Folke |year=2009 |doi=10.1007/978-0-387-73033-2 |publisher=Springer|isbn=978-0-387-73032-5 |s2cid=132900160 }}</ref>{{rp|142}} To them, caribou — ''vadzaih'' — is the cultural symbol and a keystone subsistence species of the Gwich'in, just as the [[American bison|American buffalo]] is to the Plains Native Americans.<ref name="Linguistics_2014">{{citation |title=Linguistic Team Studies Caribou Anatomy |first=Craig |last=Mishler |url=http://www.arcus.org/witness-the-arctic/2014/3/article/22797= |work=Arctic Research Consortium of the United States (ARCOS) |year=2014 |access-date=11 January 2015 |quote="A fundamental question for the research is to elicit not only what the Gwich'in know about caribou anatomy, but how they see caribou and what they say and believe about caribou that defines themselves, their dietary and nutritional needs, and their subsistence way of life." |url-status=live |archive-date=10 February 2016 |archive-url=https://web.archive.org/web/20160210131053/https://www.arcus.org/witness-the-arctic/2014/3/article/22797=}}</ref> Innovative [[Language revitalization|language revitalisation]] projects are underway to document the language and to enhance the writing and translation skills of younger Gwich'in speakers. In one project, lead research associate and fluent speaker Gwich'in elder Kenneth Frank works with linguists who include young Gwich'in speakers affiliated with the [[Alaska Native Language Center]] at the [[University of Alaska Fairbanks|University of Alaska]] in [[Fairbanks, Alaska|Fairbanks]] to document traditional knowledge of caribou anatomy. The main goal of the research was to "elicit not only what the Gwich'in know about caribou anatomy, but how they see caribou and what they say and believe about caribou that defines themselves, their dietary and nutritional needs, and their subsistence way of life."<ref name="Linguistics_2014" /> Elders have identified at least 150 descriptive Gwich'in names for all of the bones, organs and tissues. Associated with the caribou's anatomy are not just descriptive Gwich'in names for all of the body parts, including bones, organs, and tissues, but also "an encyclopedia of stories, songs, games, toys, ceremonies, traditional tools, skin clothing, personal names and surnames, and a highly developed ethnic cuisine."<ref name="Linguistics_2014" /> In the 1980s, Gwich'in Traditional Management Practices were established to protect the Porcupine caribou, upon which the Gwich'in depend. They "codified traditional principles of caribou management into tribal law" which include "limits on the harvest of caribou and procedures to be followed in processing and transporting caribou meat" and limits on the number of caribou to be taken per hunting trip.<ref name="Caulfield_1983">{{citation |first=Richard |last=Caulfield |year=1983 |title=Gwich'in Traditional Management Practices |url=http://arcticcircle.uconn.edu/ANWR/anwrgwichin1.html |series=Report to the Division of subsistence of the Alaska Department of Fish and Game |access-date=30 October 2017 |archive-url=https://web.archive.org/web/20171020081541/http://arcticcircle.uconn.edu/ANWR/anwrgwichin1.html |archive-date=20 October 2017 |url-status=live}}</ref>

=== Indigenous Eurasians ===
Reindeer herding has been vital for the subsistence of several Eurasian nomadic indigenous peoples living in the circumpolar Arctic zone such as the [[Sámi people|Sámi]], [[Nenets people|Nenets]], and [[Komi peoples|Komi]].<ref>{{Cite journal|date=2016-09-01|title=Permafrost and indigenous land use in the northern Urals: Komi and Nenets reindeer husbandry|title-link=doi|journal=Polar Science|volume=10 |issue=3|pages=278–287 |doi=10.1016/j.polar.2016.07.002|issn=1873-9652|doi-access=free|last1=Istomin |first1=Kirill V.|last2=Habeck|first2=Joachim Otto|bibcode=2016PolSc..10..278I}}</ref> Reindeer are used to provide renewable sources and reliable transportation. In Mongolia, the [[Dukha people|Dukha]] are known as the reindeer people. They are credited as one of the world's earliest domesticators. The Dukha diet consists mainly of reindeer dairy products.<ref>Keay, Morgan G. "The Tsaatan Reindeer Herders of Mongolia: Forgotten lessons of ·human-animal systems" in ''Encyclopedia of Animals and Humans''.</ref>

Reindeer husbandry is common in northern [[Fennoscandia]] (northern [[Norway]], [[Sweden]] and [[Finland]]) and the [[Russian North]]. In some human groups such as the Eveny, wild reindeer and domestic reindeer are treated as different kinds of beings.<ref>{{Cite journal|last=Lavrillier|first=Alexandra|date=2020|title="Spirit-Charged" Humans in Siberia: Interrelations between the Notions of the Individual ("Spirit Charge" and "Active Imprint") and (Ritual) Action|journal=Arctic Anthropology|volume=57|issue=1|pages=72–99|doi=10.3368/aa.57.1.72 |s2cid=230507240|issn=0066-6939}}</ref>

=== Husbandry ===
{{Main|Reindeer herding}}
[[File:Archangel reindeer3.jpg|thumb|A team pulling a sled near [[Arkhangelsk Governorate|Arkhangelsk]], Russia, late 19th-century [[photochrom]]]]
[[File:Reindeer milking.jpg|thumb|Milking in [[Finnmark|Western Finnmark]], Norway, 19th century]]

The reindeer is the only successfully semi-domesticated deer on a large scale in the world. Reindeer in northern [[Fennoscandia]] (northern [[Norway]], [[Sweden]] and [[Finland]]) as well in the [[Kola Peninsula]] and [[Sakha Republic|Yakutia]] in Russia, are mostly semi-domesticated reindeer, ear-marked by their owners. Some reindeer in the area are truly domesticated, mostly used as draught animals (nowadays commonly for tourist entertainment and races, traditionally important for the nomadic Sámi). Domestic reindeer have also been used for milk, e.g., in Norway.

There are only two genetically pure populations of wild reindeer in Northern Europe: wild mountain reindeer (''R. t. tarandus'') that live in central Norway, with a population in 2007 of between 6,000 and 8,400 animals;<ref>{{cite web|title=Wild reindeer in Norway|first=Erik|last=Lund|url=http://www.sami.uit.no/srh/norge.pdf#page=14|archive-url=https://web.archive.org/web/20070611235100/http://www.sami.uit.no/srh/norge.pdf#page=14|url-status=dead|archive-date=11 June 2007}}</ref> and wild Finnish forest reindeer (''R. t. fennicus'') that live in central and eastern Finland and in Russian [[Karelia]], with a population of about 4,350, plus 1,500 in [[Arkhangelsk Oblast]] and 2,500 in [[Komi Republic|Komi]].<ref>{{cite web|title=Wild Forest Reindeer|publisher=State Forest Enterprise of Finland|url=http://www.suomenpeura.fi/en/home-page.html|url-status=live|archive-url=https://web.archive.org/web/20170410033658/http://www.suomenpeura.fi/en/home-page.html|archive-date=10 April 2017}}</ref> East of Arkhangelsk, both wild Siberian tundra reindeer (''R. t. sibiricus'') (some herds are very large) and domestic reindeer (''R. t. domesticus'') occur with almost no interbreeding by wild reindeer into domestic clades and none the other way (Kharzinova et al. 2018;<ref>Kharzinova, V.R.; Dotsev, A.V.; Deniskova, T.E.; Solovieva, A.D.; Fedorov, V.I.; Layshev, K.A.; Romanenko, T.M.; Okhlopkov, I.M.; Wimmers, K.; Reyer, H. (2018) Genetic diversity and population structure of domestic and wild reindeer (''Rangifer tarandus'' L. 1758): A novel approach using BovineHD BeadChip. PloS one 13: e0207944. {{doi|10.1371/journal.pone.0207944}}</ref> Rozhkov et al. 2020<ref name="Rozhkov-2020" />).

DNA analysis indicates that reindeer were independently domesticated at least twice: in [[Fennoscandia]] and Western [[Russia]] (and possibly also Eastern Russia).<ref>{{cite journal|doi=10.1098/rspb.2008.0332 |title=Genetic analyses reveal independent domestication origins of Eurasian reindeer |journal=Proceedings of the Royal Society B: Biological Sciences |volume=275 |issue=1645 |pages=1849–55|year=2008 |last1=Roed |first1=K. H |last2=Flagstad |first2=O. |last3=Nieminen |first3=M. |last4=Holand |first4=O. |last5=Dwyer |first5=M. J. |last6=Rov |first6=N. |last7=Vila |first7=C. |pmid=18460427 |pmc=2593925}}</ref> Reindeer have been [[Herding|herded]] for centuries by several Arctic and sub-Arctic peoples, including the [[Sámi people|Sámi]], the [[Nenets people|Nenets]] and the [[Yakuts]]. They are raised for their meat, hides and antlers and, to a lesser extent, for milk and transportation. Reindeer are not considered fully domesticated, as they generally roam free on pasture grounds. In traditional nomadic herding, reindeer herders migrate with their herds between coastal and inland areas according to an annual migration route and herds are keenly tended. However, reindeer were not bred in captivity, though they were tamed for milking as well as for use as draught animals or [[Working animal|beasts of burden]]. Millais (1915),<ref name="Millais-1915" /> for example, shows a photograph (Plate LXXX) of an "Okhotsk Reindeer" saddled for riding (the rider standing behind it) beside an officer astride a steppe pony that is only slightly larger. [[List of domesticated animals#Tame, partially domesticated, and widely captive-bred animals|Domestic reindeer]] are shorter-legged and heavier than their wild counterparts.{{Citation needed|date=May 2012}} In Scandinavia, management of reindeer herds is primarily conducted through ''[[siida]]'', a traditional Sámi form of cooperative association.<ref name="Korpijaakko-Mikkel March 22, 2009">{{Cite journal|title=Siida and traditional Sami reindeer herding knowledge |last=Korpijaakko-Mikkel|first=Sara |date=March 22, 2009 |journal=Northern Review |url=http://www.highbeam.com/doc/1G1-202252650.html|archive-url=https://web.archive.org/web/20110501035825/http://www.highbeam.com/doc/1G1-202252650.html|url-status=dead|archive-date=May 1, 2011}}</ref>

The use of reindeer for transportation is common among the nomadic peoples of the [[Russian North]] (but not anymore in Scandinavia). Although a sled drawn by 20 reindeer will cover no more than {{cvt|20|–|25|km}} a day (compared to {{cvt|7|–|10|km}} on foot, {{cvt|70|–|80|km}} by a dog sled loaded with cargo and {{cvt|150|–|180|km}} by a dog sled without cargo), it has the advantage that the reindeer will discover their own food, while a pack of 5–7 sled dogs requires {{cvt|10|–|14|kg}} of fresh fish a day.<ref>{{cite book|last=Kerblay|first=Basile|title=Русская культура. Этнографические очерки|trans-title=Russian Culture. Ethnographic notes|translator-first=Yaroslav|translator-last=Bogdanov|location=Saint Petersburg, Russia|publisher=Европейский дом |date=2008|page=149|language=ru}} (Referencing: {{cite book|editor1-last=Dolgikh|editor1-first=B.O.|editor2-last=Gurvich|editor2-first=I.S.|title=Преобразования в хозяйстве и культуре и этнические процессы у народов севера|trans-title=Transformations of Economy and Culture and Ethnic Processes of the Peoples of the North|location=Moscow|publisher=Nauka|date=1970|page=139 |language=ru}})</ref>

[[File:Reindeer hides for sale.jpg|thumb|Reindeer hides for sale in [[Sitka, Alaska]]]]

The use of reindeer as semi-domesticated livestock in Alaska was introduced in the late 19th century by the [[United States Revenue Cutter Service]], with assistance from [[Sheldon Jackson]], as a means of providing a livelihood for [[Alaska Natives]].<ref>King, Irving H. (1996). ''The Coast Guard Expands'', pp. 86–91. Naval Institute Press, Annapolis, Maryland. {{ISBN|1-55750-458-X}}.</ref> Reindeer were imported first from Siberia and later also from Norway. A regular mail run in [[Wales, Alaska]], used a sleigh drawn by reindeer.<ref name="Govt. Print. Off">{{cite book |author1=United States. Bureau of Education |author2=United States. Bureau of Education. Alaska Division |title=Annual report on introduction of domestic reindeer into Alaska |url=https://books.google.com/books?id=6RcWb-PNMiMC&pg=PA18 |access-date=16 September 2011 |year=1905 |publisher=Govt. Print. Off. |pages=18–|volume=14 |url-status=live |archive-url=https://web.archive.org/web/20140101074445/http://books.google.com/books?id=6RcWb-PNMiMC&pg=PA18 |archive-date=1 January 2014 }}</ref> In Alaska, reindeer herders use [[satellite]] telemetry to track their herds, using online maps and databases to chart the herd's progress.{{Citation needed|date=May 2012}}

[[Domestication|Domestic]] reindeer are mostly found in northern [[Fennoscandia]] and the [[Russian North]], with a herd of approximately 150–170 reindeer living around the [[Cairngorms]] region in [[Scotland]]. The last remaining wild tundra reindeer in Europe are found in portions of southern Norway.<ref name="newscientist.com">[https://www.newscientist.com/article.ns?id=dn4491 Europe's last wild reindeer herds in peril] {{webarchive |url=https://web.archive.org/web/20080205174121/http://www.newscientist.com/article.ns?id=dn4491 |date=5 February 2008}}. Newscientist. 19 December 2003. Retrieved on 16 September 2011.</ref> The International Centre for Reindeer Husbandry (ICR), a circumpolar organisation, was established in 2005 by the Norwegian government. ICR represents over 20 indigenous reindeer peoples and about 100,000 reindeer herders in nine different national states.<ref name="ICR2005">{{cite web |url=http://reindeerherding.org/ |title=Reindeer Herding: a virtual guide to reindeer and those who herd them |institution=International Centre for Reindeer Husbandry (ICR), Government of Norway|location=Kautokeino|access-date=15 January 2014|url-status=live|archive-url=https://web.archive.org/web/20131229154038/http://reindeerherding.org/|archive-date=29 December 2013}}</ref> In Finland, there are about 6,000 reindeer herders, most of whom keep small herds of less than 50 reindeer to raise additional income. With 185,000 reindeer ({{as of|2001|lc=yes}}), the industry produces {{convert|2,000|MT|ST}} of reindeer meat and generates 35 million euros annually. 70% of the meat is sold to slaughterhouses. Reindeer herders are eligible for national and EU [[Agricultural subsidy|agricultural subsidies]], which constituted 15% of their income. Reindeer herding is of central importance for the local economies of small communities in sparsely populated rural Sápmi.<ref>[http://www.paliskunnat.fi/kestava_porotalous/08_Suomen_porotalous.pdf Suomen porotalous] {{webarchive |url=https://web.archive.org/web/20131019231911/http://www.paliskunnat.fi/kestava_porotalous/08_Suomen_porotalous.pdf |date=19 October 2013}}. paliskunnat.fi (in Finnish)</ref>
 	
Currently, many reindeer herders are heavily dependent on [[diesel fuel]] to provide for [[electric generator]]s and [[snowmobile]] transportation, although solar [[Photovoltaics|photovoltaic]] systems can be used to reduce diesel dependency.<ref>{{cite journal |title=Technical viability of mobile solar photovoltaic systems for indigenous nomadic communities in northern latitudes |journal=Renewable Energy |volume=89 |pages=253–267 |year=2016 |last1=Obydenkova |first1=Svetlana V. |last2=Pearce |first2=Joshua M. |s2cid=110090767 |url=https://hal.archives-ouvertes.fr/hal-02113570/file/Technical_viability_of_mobile_solar_phot.pdf |doi=10.1016/j.renene.2015.12.036|bibcode=2016REne...89..253O }}</ref>
<gallery mode="packed" heights="130" caption="[[Miniature (illuminated manuscript)|Miniatures]] of reindeer from [[Olaus Magnus]]'s 1539 ''[[Carta marina]]''">
File:Carta Marina - milking reindeer.jpg|Milking
File:Carta Marina - reindeer crossing a frozen lake.jpg|Crossing frozen water
File:Carta Marina - reindeer-drawn waggon with bowman.jpg|Drawing a wagon
File:Carta Marina - reindeer-drawn sled.jpg|Drawing a one-man sled
File:Carta Marina - reindeer-mounted warriors.jpg|Reindeer-mounted cavalry
</gallery>

=== History ===
Reindeer hunting by humans has a very long history.

{{blockquote| Wild reindeer "may well be the species of single greatest importance in the entire anthropological literature on hunting."<ref name="Burch" />}}

Both [[Aristotle]] and [[Theophrastus]] have short accounts – probably based on the same source – of an ox-sized deer species, named ''[[Tarand (animal)|tarandos]]'', living in the land of the [[Budini|Bodines]] in [[Scythia]], which was able to change the colour of its fur to obtain camouflage. The latter is probably a misunderstanding of the seasonal change in reindeer fur colour. The descriptions have been interpreted as being of reindeer living in the southern [[Ural Mountains]] in c. 350 BC.<ref name=Sarauw>{{Cite book|last1= Sarauw |first1= Georg | author-link1= Georg F.L. Sarauw |editor1-first= H. F. E. |editor1-last= Jungersen |editor2-first= E. |editor2-last= Warming |editor2-link= Eugenius Warming | title= Mindeskrift i Anledning af Hundredeaaret for Japetus Steenstrups Fødsel |chapter= Das Rentier in Europa zu den Zeiten Alexanders und Cæsars |trans-chapter= The reindeer in Europe to the times of Alexander the Great and Julius Caesar|year= 1914 |location= Copenhagen |language= de |pages= 1–33 |title-link= Japetus Steenstrup |publisher=Royal Danish Academy of Sciences and Letters}}</ref>
[[File:ReindeerTOP.jpg|thumb|upright|The tragelaphus or deer-goat]]
A deer-like animal described by [[Julius Caesar]] in his ''[[Commentarii de Bello Gallico]]'' (chapter 6.26) from the [[Hercynian Forest]] in the year 53 BC is most certainly to be interpreted as a reindeer:<ref name=Sarauw/><ref>{{cite book |quote=Est bos cervi figura, cuius a media fronte inter aures unum cornu* exsistit excelsius magisque directum his, quae nobis nota sunt, cornibus: ab eius summo sicut palmae ramique* late diffunduntur. Eadem est feminae marisque natura, eadem forma magnitudoque cornuum. |year=1898 |last1=Greenough |first1=J. B. |last2=D'Ooge |first2=Benjamin L. |last3=Daniell |first3=M. Grant |title=Commentary on Caesar, Gallic War |chapter=book 6, chapter 26 |publisher=Ginn and Company |location=Boston |chapter-url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0017&redirect=true |archive-url= https://web.archive.org/web/20120426165859/http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0017&redirect=true |url-status=live |archive-date=26 April 2012}}</ref>
{{blockquote|There is an [[ox]] shaped like a [[Deer|stag]]. In the middle of its forehead a single horn grows between its ears, taller and straighter than the animal horns with which we are familiar. At the top this horn spreads out like the palm of a hand or the branches of a tree. The females are of the same form as the males, and their horns are the same shape and size.}}

According to [[Olaus Magnus]]'s ''[[A Description of the Northern Peoples|Historia de Gentibus Septentrionalibus]]'' – printed in [[Rome]] in the year 1555 – [[Gustav I of Sweden]] sent 10 reindeer to [[Albert, Duke of Prussia]], in the year 1533. It may be these animals that [[Conrad Gessner]] had seen or heard of.

During [[World War II]], the [[Soviet Army]] used reindeer as [[pack animal]]s to transport food, ammunition and post from [[Murmansk]] to the [[Karelian Front|Karelian front]] and bring wounded soldiers, pilots and equipment back to the base. About 6,000 reindeer and more than 1,000 reindeer herders were part of the operation. Most herders were [[Nenets people|Nenets]], who were mobilised from the [[Nenets Autonomous Okrug]], but reindeer herders from the Murmansk, [[Arkhangelsk Oblast|Arkhangelsk]] and [[Komi Republic|Komi]] regions also participated.<ref>Trude Pettersen: [http://barentsobserver.com/en/topics/war-memorial-honor-wwii-reindeer-battalions War memorial to honor WWII reindeer battalions] {{webarchive |url=https://web.archive.org/web/20130620161807/http://barentsobserver.com/en/topics/war-memorial-honor-wwii-reindeer-battalions |date=20 June 2013}}. Barents Observer, 27 February 2012</ref><ref>[https://www.npr.org/2011/08/14/139619834/when-reindeer-helped-win-wwii In WWII, Reindeer Were Our Animal Allies] {{webarchive |url=https://web.archive.org/web/20131029204028/http://www.npr.org/2011/08/14/139619834/when-reindeer-helped-win-wwii |date=29 October 2013}}. [[National Public Radio]], 14 August 2011</ref>

=== Santa Claus ===
[[File:reindeer.yate.arp.750pix.jpg|thumb|Relaxing after pulling Santa's sleigh at the switching on of Christmas lights in Scotland]]
{{Main|Santa Claus's reindeer}}

Around the world, public interest in reindeer peaks during the Christmas season.<ref>{{cite web|url=http://icr.arcticportal.org/index.php?option=com_content&view=article&id=142:flying-reindeer-and-santa-claus-&catid=2:feature-archive&Itemid=7|title=Flying Reindeer and Santa Claus: Fact, Fiction and Myth|first=Philip|last=Burgess|date=15 December 2008|website=International Centre of Husbandry, Norway|access-date=15 January 2014|url-status=live|archive-url=https://web.archive.org/web/20131029201212/http://icr.arcticportal.org/index.php?option=com_content&view=article&id=142:flying-reindeer-and-santa-claus-&catid=2:feature-archive&Itemid=7|archive-date=29 October 2013}}</ref> According to [[folklore]], [[Santa Claus]]'s sleigh is pulled by flying reindeer. These reindeer were first named in the 1823 poem "[[A Visit from St. Nicholas]]".

=== Mythology and art ===
Among the Inuit, there is a story of the origin of the caribou:<ref name="CanadasArctic2002a">{{citation|year=2002|url=http://www.arctic.uoguelph.ca/cpl/Traditional/traditional/animals/caribou.htm|title=Tuktu — Caribou|location=Guelph, Ontario|work=Canada's Arctic|access-date=17 January 2014|url-status=live|archive-url=https://web.archive.org/web/20150923173415/http://www.arctic.uoguelph.ca/cpl/Traditional/traditional/animals/caribou.htm|archive-date=23 September 2015}}</ref>
{{blockquote|Once upon a time there were no caribou on the earth. But there was a man who wished for caribou, and he cut a hole deep in the ground, and up this hole came caribou, many caribou. The caribou came pouring out, until the earth was almost covered with them. And when the man thought there were caribou enough for mankind, he closed up the hole again. Thus the caribou came up on earth.|<ref name="CanadasArctic2002a" />}}

Inuit artists from the Barrenlands<!-- -which include the Ahiarmiut/Ihalmiut—originally from the north of the Back River area and from Ennadai Lake; the Akilinirmiut, originally from the Akiliniq Hills, the Thelon River area of Beverly Lake, Dubawnt Lake and Aberdeen Lake; the Hanningajurmiut, originally from Garry Lake; the Harvaqtuurmiut, originally from the Kazan River area; the Hauniqturmiut, originally from Whale Cove's southern region, between Sandy Point and Arviat; the Iluilirmiut/Illuilirmiut, originally from Adelaide Peninsula (Iluilik) and the Chantrey Inlet area; the Kihlirnirmiut, originally from the Garry Lake area between Bathurst Inlet, Cambridge Bay; the Natsilingmiut, originally from the Baker Lake area between Gjoa Haven, Taloyoak, Kugaaruk and Repulse Bay; the Padlermiut, originally from the Baker Lake to Arviat area; the Qaernermiut, originally from the lower Thelon River, Baker Lake, Chesterfield Inlet and Corbett Inlet areas, between Rankin Inlet and Whale Cove and the Utkuhiksalingmiut, originally from the Back River and Gjoa Haven/Wager Bay area- --> incorporate depictions of caribou — and items made from caribou antlers and skin — in carvings, drawings, prints and sculpture.

Contemporary Canadian artist [[Brian Jungen]], of [[Dane-zaa]] First Nations ancestry, commissioned an installation entitled "The ghosts on top of my head" (2010–11) in [[Banff, Alberta]], which depicts the antlers of caribou, elk and moose.<ref name="Hornsby2011">{{cite web|title=The ghosts on top of my head: Iconic sculpture creates campus focal point|last=Hornsby|first=Debra|date=25 August 2011|location=Banff, Alberta|access-date=31 January 2014|url=http://www.banffcentre.org/blog/2011/08/25/the-ghosts-on-top-of-my-head-iconic-sculpture-creates-campus-focal-point/|archive-url=https://web.archive.org/web/20140202204906/http://www.banffcentre.org/blog/2011/08/25/the-ghosts-on-top-of-my-head-iconic-sculpture-creates-campus-focal-point/|archive-date=2 February 2014}}</ref>
{{blockquote|I remember a story my Uncle Jack told me – a Dunne-Za creation story about how animals once ruled the earth and were ten times their size and that got me thinking about scale and using the idea of the antler, which is a thing that everyone is scared of, and making it into something more approachable and abstract.|Brian Jungen, 2011<ref name="Hornsby2011" />}}

[[Tomson Highway]], [[Order of Canada|CM]]<ref name=canenc>[http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1ARTA0010891 Tomson Highway] {{webarchive |url=https://web.archive.org/web/20110607115857/http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1ARTA0010891 |date=7 June 2011}}. [[The Canadian Encyclopedia]].</ref> is a [[Canadians|Canadian]] and [[Cree]] [[playwright]], [[novelist]], and [[Children's literature|children's author]], who was born in a remote area north of [[Brochet, Manitoba|Brochet]], [[Manitoba]].<ref name=canenc /> His father, Joe Highway, was a caribou hunter. His 2001 children's book entitled ''Caribou Song''/''atíhko níkamon'' was selected as one of the "Top 10 Children's Books" by the Canadian newspaper ''[[The Globe and Mail]]''. The young protagonists of ''Caribou Song'', like Tomson himself, followed the caribou herd with their families.

=== Heraldry and symbols ===
[[File:Kuusamo.vaakuna.svg|thumb|upright|[[Coat of arms]] of [[Kuusamo]]|alt=[[Coat of arms]] of [[Kuusamo]] features a male]]
[[File:Inari.vaakuna.svg|thumb|upright|Coat of arms of [[Inari, Finland|Inari]]|alt=Coat of arms of [[Inari, Finland|Inari]], a fish with antlers]]
Several Norwegian municipalities have one or more reindeer depicted in their coats-of-arms: [[Eidfjord Municipality]], [[Porsanger Municipality]], [[Rendalen Municipality]], [[Tromsø Municipality]], [[Vadsø Municipality]], and [[Vågå Municipality]]. The historic province of [[Västerbotten]] in [[Sweden]] has a reindeer in its coat of arms. The present [[Västerbotten County]] has very different borders and uses the reindeer combined with other symbols in its coat-of-arms. The city of [[Piteå]] also has a reindeer. The logo for [[Umeå University]] features three reindeer.<ref>{{cite web |url=http://www.infoenheten.umu.se/grafisk-profil/logotyp/ |archive-url=https://archive.today/20130418134454/http://www.infoenheten.umu.se/grafisk-profil/logotyp/ |url-status=dead |archive-date=18 April 2013 |title=Logotyp |language=Swedish |publisher=[[Umeå University]] |access-date=7 March 2012 }}</ref>

The Canadian 25-cent coin or "[[Quarter (Canadian coin)|quarter]]" features a depiction of a caribou on one face. The caribou is the official provincial animal of [[Newfoundland and Labrador]], Canada, and appears on the [[coat of arms of Nunavut]]. A caribou statue was erected at the centre of the [[Beaumont-Hamel Newfoundland Memorial]], marking the spot in France where hundreds of soldiers from Newfoundland were killed and wounded in [[World War I]]. There is a replica in [[Bowring Park (St. John's)|Bowring Park]] in St. John's, Newfoundland's capital city.<ref>{{cite web|title=Beaumont Hamel Newfoundland Memorial |website=Canada and the First World War |publisher=Canadian War Museum |url=https://www.warmuseum.ca/firstworldwar/history/after-the-war/remembrance/beaumont-hamel-newfoundland-memorial/ |access-date=2021-02-16}}</ref>

Two municipalities in Finland have reindeer motifs in their coats-of-arms: [[Kuusamo]] has a running reindeer;<ref>[http://www.kuusamo.fi/Resource.phx/sivut/sivut-kuusamo/yleistietoa/tunnukset.htx Coat of arms for Kuusamo] {{webarchive |url=https://web.archive.org/web/20120724061159/http://www.kuusamo.fi/Resource.phx/sivut/sivut-kuusamo/yleistietoa/tunnukset.htx |date=24 July 2012}}. Kuusamo.fi. Retrieved on 19 April 2014.</ref> and [[Inari, Finland|Inari]] has a fish with reindeer antlers.<ref>[http://www.inari.fi/fi/inari-info/viestintamateriaalia/inarin-vaakuna.html Coat of arms for Inari] {{webarchive |url=https://web.archive.org/web/20130619014605/http://www.inari.fi/fi/inari-info/viestintamateriaalia/inarin-vaakuna.html |date=19 June 2013}}. Inari.fi.</ref>

== See also ==
* [[Alaska Reindeer Service]]
* [[Caribou herds and populations in Canada]]
* [[Rangifer (constellation)]]
* [[Rangifer (journal)|''Rangifer'' (journal)]]
* [[Reindeer Police]]

== Notes ==
{{notelist}}

== References ==
{{Reflist|30em}}

== Bibliography ==
*{{cite web|ref=COSEWIC|title=Designatable Units for Caribou (''Rangifer tarandus'') in Canada|url=http://www.cosewic.gc.ca/eng/sct12/COSEWIC_Caribou_DU_Report_23Dec2011.pdf|website=COSEWIC|year=2011|institution=Committee on the Status of Endangered Wildlife in Canada|location=Ottawa, Ontario|access-date=18 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20160303234528/http://www.cosewic.gc.ca/eng/sct12/COSEWIC_Caribou_DU_Report_23Dec2011.pdf|archive-date=3 March 2016}}

== External links ==
{{Commons and category|Rangifer tarandus|Rangifer tarandus}}

{{Wikispecies|Rangifer tarandus}}
{{Wiktionary|reindeer|caribou}}
* {{citation|url=http://westernarcticcaribou.org/wp-content/uploads/2012/08/CT2012_FINAL_0628_lowresolution.pdf|newspaper=Caribou Trails: News from the Western Arctic Caribou Herd Working Group|title=Caribou Census Complete: 325,000 animals|institution=Western Arctic Caribou Herd Working Group|date=August 2012|location=Nome, Alaska}} – the 2011 census results of the WACH, which is Alaska's largest caribou herd.
* [http://www.reindeerportal.org/ The Reindeer Portal, Source of Information About Reindeer Husbandry Worldwide]
* [https://web.archive.org/web/20130605052633/http://www.pwnhc.ca/timeline/index_winIFix.asp?forward=http%3A%2F%2Fwww.pwnhc.ca%2Ftimeline%2F1925%2FReindeer_1935.htm#Scene_1 1935 Reindeer Herding in the Northwest Territories]
* [http://www.nps.gov/archive/bela/html/rangifer.htm General information on Caribou and Reindeer]
* [https://web.archive.org/web/20051023182634/http://www.rangifer.net/rangifer/index.cfm Human Role in Reindeer/Caribou Systems]
* [https://archive.today/20121220062008/http://www.villreinfangst.no/eng/index.php Reindeer hunting as World Heritage – a ten-thousand-year-long tradition]
* [http://reindeer.salrm.uaf.edu/ Reindeer Research Program – Alaska reindeer research and industry development] {{Webarchive|url=https://web.archive.org/web/20210428223449/http://reindeer.salrm.uaf.edu/ |date=28 April 2021 }}
* [http://reindeer.salrm.uaf.edu/about_reindeer/adaptations/index.php#Adaptations%20To%20Life%20In%20The%20Arctic Adaptations To Life In The Arctic] {{Webarchive|url=https://web.archive.org/web/20101212060456/http://reindeer.salrm.uaf.edu/about_reindeer/adaptations/index.php#Adaptations%20To%20Life%20In%20The%20Arctic |date=12 December 2010 }} – Instructional slide-show, University of Alaska
* [https://web.archive.org/web/20081220103800/http://www.ub.uit.no/baser/rangifer/ ''Rangifer''] – world's only scientific journal dealing exclusively with husbandry, management and biology of Arctic and northern ungulates
*{{Wikisource-inline|list=
**{{Cite Americana|wstitle=Caribou|last=Ingersoll |first=Ernest |author-link=Ernest Ingersoll |short=x |noicon=x}}
**{{Cite EB1911|wstitle=Reindeer|last=Lydekker |first=Richard |author-link=Richard Lydekker |short=x |noicon=x}}
**{{Cite NIE|wstitle=Reindeer |year=1905 |short=x |noicon=x}}
}}
*{{cite web|website=[[United States Geological Survey]]|url=http://www.usgs.gov/blogs/features/usgs_top_story/the-other-364-days-of-the-year-the-real-lives-of-wild-reindeer-3/|title=The Other 364 Days of the Year: The Real Lives of Wild Reindeer Categories: Biology and Ecosystems|date=15 December 2014|author=Puckett, Catherine|author2=Landis, Ben|access-date=24 December 2014|archive-date=26 November 2015|archive-url=https://web.archive.org/web/20151126034043/http://www.usgs.gov/blogs/features/usgs_top_story/the-other-364-days-of-the-year-the-real-lives-of-wild-reindeer-3/|url-status=dead}}
*{{cite web|website=ScienceDaily|url=https://www.sciencedaily.com/articles/r/reindeer.htm|title=Reference Article: Reindeer (caribou)|access-date=25 December 2015|archive-url=https://web.archive.org/web/20150318081717/http://www.sciencedaily.com/articles/r/reindeer.htm|archive-date=18 March 2015|url-status=dead}}
* [https://archives-manuscripts.dartmouth.edu/repositories/2/resources/1192 ''Growth Studies in the Reindeer'' by Charles J. Krebs] at Dartmouth College Library
* [https://www.laits.utexas.edu/sami/diehtu/siida/reindeer/Reindeer/reindeer_main.html The Sami and their Reindeer], University of Texas, Austin
* {{cite web | title=What's the Difference: Reindeer vs. Caribou | website=[[National Park Service]] | date=October 25, 2022 | url=https://www.nps.gov/articles/000/reinderrvscaribou.htm | access-date=November 23, 2022}}

=== Caribou-specific links (North America) ===
* [https://web.archive.org/web/20061206062749/http://arctic.fws.gov/carcon.htm Frequently Asked Questions about Caribou] from the [[Arctic National Wildlife Refuge]]
* [http://www.caribouandyou.ca Caribou and You] – Campaign by [[Canadian Parks and Wilderness Society|CPAWS]] to protect the boreal woodland caribou, a subspecies at risk in Canada
* [http://www.releases.gov.nl.ca/releases/2008/env/0207n06.htm Newfoundland Five-Year Caribou Strategy Seeks to Address Declining Populations]

{{Artiodactyla|R.1}}
{{Working animals}}
{{Taxonbar|from=Q39624}}
{{Authority control}}

[[Category:Reindeer| ]]
[[Category:Alaskan cuisine]]
[[Category:Mammals described in 1758]]
[[Category:Arctic land animals]]
[[Category:Capreolinae]]
[[Category:Mammals of the Arctic]]
[[Category:Holarctic fauna]]
[[Category:Livestock]]
[[Category:Mammals of Asia]]
[[Category:Mammals of Canada]]
[[Category:Mammals of Greenland]]
[[Category:Mammals of Europe]]
[[Category:Mammals of Russia]]
[[Category:Mammals of the United States]]
[[Category:Pack animals]]
[[Category:Taxa named by Carl Linnaeus]]