Editing Reindeer (section)

== 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|bibcode=2006MamRv..36..251S
 }}</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|url-access=subscription }}</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|url-access=subscription }}</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=usurped |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>