The reindeer (caribou in North America) is a widespread and numerous species in the northern Holarctic, being present in both tundra and taiga (boreal forest).Novak, R. M. (editor) (1999). Walker's Mammals of the World. Vol. 2. 6th edition. Johns Hopkins University Press, Baltimore. pp. 1128–1130. Originally, the reindeer was found in Scandinavia, eastern Europe, Russia, Mongolia, and northern China north of the 50th latitude. In North America, it was found in Canada, Alaska (United States), and the northern contiguous USA from Washington to Maine. In the 19th century, it was apparently still present in southern Idaho. It also occurred naturally on Sakhalin, Greenland, and probably even in historical times in Ireland.
During the late Pleistocene era, reindeer were found further south, such as at Nevada, Tennessee, and AlabamaC. S. Churcher, P. W. Parmalee, G. L. Bell, and J. P. Lamb, 1989, Caribou from the Late Pleistocene of northwestern Alabama, Canadian Journal of Zoology in North America and Spain in Europe. Today, wild reindeer have disappeared from many areas within this large historical range, especially from the southern parts, where it vanished almost everywhere. Populations of wild reindeer are still found in Norway, Finland, Siberia, Greenland, Alaska, and Canada.
The George River reindeer herd in the tundra of Quebec and Labrador in eastern Canada, once numbered world's largest 800,000–900,000 animals, stands December 2011 at 74,000—a drop of up to 92% because of Iron-ore mining, flooding for hydropower and road building.Christmas reindeer mystery as world's largest herd plummets Survival 21 December
Domesticated reindeer are mostly found in northern Fennoscandia and Russia, with a herd of approximately 150–170 semi-domesticated reindeer living around the Cairngorms region in Scotland. Although formerly more widespread in Scandinavia, the last remaining wild mountain reindeer in Europe are found in portions of southern Norway.Europe's last wild reindeer herds in peril. Newscientist. 19 December 2003. Retrieved on 2011-09-16. Siberian tundra reindeer are widespread in Russia.
A few reindeer from Norway were introduced to the South Atlantic island of South Georgia in the beginning of the 20th century. The South Georgian reindeer totaled some estimated 2600 animals in two distinct herds separated by glaciers. Although the flag and the coat of arms of the territory contain an image of a reindeer, they were eradicated from 2013 to 2017 because of the environmental damage they caused. Around 4000 reindeer have been introduced into the French sub-Antarctic archipelago of Kerguelen Islands. East Iceland has a small herd of about 2,500–3,000 animals.Reindeer Hunting in Iceland. International Adventure. Accessed 12 November 2010.
Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range.BBC Earth News-Reindeer herds in global decline. BBC News (2009-06-11). Retrieved on 2011-09-16. This global decline is linked to climate change for northern, migratory caribou and reindeer herds and industrial disturbance of caribou habitat for sedentary, non-migratory herds.
Russia
In 2013, the Taimyr herd in Russia was the largest herd in the world. In 2000, the herd increased to 1,000,000 but by 2009, there were 700,000 animals. In the 1950s, there were 110,000.
There are three large herds of migratory tundra wild reindeer in central Siberia's Yakutia region: the Lena-Olenek, Yana-Indigirka and Sundrun herds. While the population of the Lena-Olenek herd is stable, the others are declining.
Further east again, the Chukotka herd is also in decline. In 1971, there were 587,000 animals. They recovered after a severe decline in 1986, to only 32,200 individuals, but their numbers fell again. According to Kolpashikov, by 2009 there were less than 70,000.
North America
Until a recent revision, there were six living subspecies of the reindeer (Rangifer tarandus), known in North America as the caribou:Mattioli S (2011) Family Cervidae: Deer. In: Wilson DE, Mittermeier RA (Eds) Handbook of the mammals of the world 2 Hoofed mammals. Lynx Edicions, Barcelona, Spain, 350-443. woodland (boreal), R. t. caribou; Labrador or Ungava caribou, R. t. caboti; Newfoundland caribou, R. t. terranovae; barren-ground caribou, R. t. groenlandicus (including the Porcupine, Dolphin-Union and other Alaskan and Canadian herds of barren-ground caribou); Osborn's caribou, R. t. oborni; and Peary caribou, R. t. pearyi.
In Canada, the Committee on Status of Endangered Wildlife in Canada (COSEWIC) defined 12 "designatable units", DU, which included the above named subspecies and several ecotypes: Peary caribou DU1, the Dolphin-Union herd of barren-ground caribou DU2, mainland barren-ground (including Alaskan) caribou DU3, Labrador caribou ("eastern migratory") caribou DU4, Newfoundland caribou DU5, boreal woodland caribou DU6, Osborn's caribou ("northern mountain") DU7, Rocky Mountain caribou ("central mountain") DU8, Selkirk Mountain caribou DU9 ("southern mountain"), Torngat Mountain DU10 (an ecotype of Labrador caribou), Atlantic-Gaspésie DU11 (a montane ecotype of woodland caribou) and the extinct Dawson's caribou DU2. Genetic research has shown that Osborn's caribou and the other two western montane ecotypes are of Beringian-Eurasian ancestry (but distantly, having diverged > 60,000 years ago) and therefore not closely relate to woodland caribou. While useful for conservation and research, Designatable units, an adaptation of "evolutionary significant units", are not phylogenetically based and cannot substitute for taxonomy.Cronin MA (2006) A proposal to eliminate redundant terminology for intra-species groups. Wildlife Society Bulletin 34: 237-241.Gippoliti S (2020) Everything mammal conservation biologists always wanted to know about taxonomy (but were afraid to ask). Journal for Nature Conservation 54: 125793.
In North America, because of its vast range in a wide diversity of ecosystems, the woodland caribou is further distinguished by a number of ecotypes. In the Ungava region of Quebec, several herds of Labrador caribou in the north, such as the large George River caribou herd, overlap in range with the boreal woodland caribou to the south.
A recent revisionHarding LE (2022) Available names for Rangifer (Mammalia, Artiodactyla, Cervidae) species and subspecies. ZooKeys 1119: 117-151. returned Woodland caribou to species status, R. caribou, with subspecies Labrador or Ungava caribou, R. c. caboti, the migratory form; Newfoundland caribou, R. c. terranovae; and Boreal woodland caribou, R. c. caribou. The revision returned the name of Arctic caribou to its original R. arcticus, with the nominate subspecies being barren-ground caribou, R. a. arcticus, and returned four western montane ecotypes to subspecies of Arctic caribou: Selkirk Mountain caribou, R. a. montanus, Rocky Mountain caribou, R. a. fortidens, Osborn's caribou, R. a. osborni, and Stone's caribou, R. a. stonei, in accordance with molecular data that showed these to be of Beringian-Eurasian ancestry.
Some caribou populations are "endangered in Canada in regions such as southeastern British Columbia at the Canadian-USA border, along the Columbia, Kootenay and Kootenai rivers and around Kootenay Lake. Selkirk Mountain caribou (formerly thought to be an ecotype of woodland caribou, Rangifer tarandus caribou) was considered endangered in the United States in Idaho and Washington. R. t. pearyi is on the IUCN endangered list. The woodland caribou is highly endangered throughout its distribution.
United States All U.S. caribou populations are in Alaska. There was also a remnant population of about a dozen caribou in the Selkirk Mountains of Idaho, which were the only remaining wild caribou in the contiguous United States. In 2018 there were three left;Reid A, DeGroot L (2018) 2018 mountain caribou census: South Selkirk Mountains. Ministry of Forests, Lands and Natural Resource Operations, Nelson, B.C., 8 pp. the last member, a female, was transported to a wildlife rehab center in Canada, thus marking the extirpation of the caribou from the Lower 48.
Alaska There are four migratory herds of barren-ground caribou, R. tarandus groenlandicus, in Alaska: the Western Arctic herd, the Teshekpuk Lake herd, the Central Arctic herd and the Porcupine caribou herd (named for a river that flows from Yukon into Alaska), the last of which is transnational as its migratory range extends far into Canada's north. The largest is the Western Arctic caribou herd, but the smaller Porcupine herd has the longest migration of any terrestrial mammal on Earth with a vast historical range. There are also about 20 montane herds in the south and east, recently returned to their former name, R. a. stonei,Anderson RM (1946) Catalogue of Canadian Recent mammals. National Museum of Canada Bulletin No. 102, Biological Series 31, Ottawa, Ontario, 238 pp. that move seasonally within their small ranges, but to not migrate per se; and one nearly insular herd on the western end of the Alaska Peninsula and nearby islands, originally described as R. granti. Allen JA (1902) A new caribou from the Alaska Peninsula. Bulletin of the American Museum of Natural History XVI: 119-127. Phylogenetic analysis shows that Grant's caribou clusters separately from all other Alaskan caribouMager KH, Colson KE, Groves P, Hundertmark KJ (2014) Population structure over a broad spatial scale driven by nonanthropogenic factors in a wide-ranging migratory mammal, Alaskan caribou. Molecular Ecology 23: 6045-6057. and does not interbreed with nearby caribou ecotypes.Colson KE, Mager KH, Hundertmark KJ (2014) Reindeer introgression and the population genetics of caribou in southwestern Alaska. Journal of Heredity 105: 585-596.
Porcupine caribou herd
The Porcupine caribou herd is transnational and migratory. The herd is named after their birthing grounds, for example, the Porcupine River, which runs through a large part of the range of the Porcupine herd. Individual herds of migratory caribou once had over a million animals per herd and could take over ten days to cross the Yukon River, but these numbers dramatically declined with habitat disturbance and degradation. Though numbers fluctuate, the herd comprises approximately 169,000 animals (based on a July 2010 photocensus). The Porcupine herd's annual migrations of are among the longest of any terrestrial mammal. Its range spans approximately , from Aklavik, Northwest Territories to Dawson City, Yukon to Kaktovik, Alaska on the Beaufort Sea. The Porcupine caribou (R. tarandus groenlandicus—originally named Tarandus rangifer ogilviensis Millais 1915 after the Ogilvie Mountains, their Yukon winter range;Millais JG (1915) The caribou. In: Carruthers D, Millais JG, Byl PBVD, Wallace HF, Kennion L-CRL, Barklay FG (Eds) The Gun at Home and Abroad. London & Counties Press Association Ltd., London, U.K., 255-280. has a vast range that includes northeastern Alaska and the Yukon and is therefore cooperatively managed by government agencies and aboriginal peoples from both countries. The Gwich'in people followed the Porcupine herd—their primary source of food, tools, and clothing—for thousands of years—according to oral tradition, for as long as 20,000 years. They continued their nomadic lifestyle until the 1870s. This herd is also traditional food for the Inupiat, the Inuvialuit, the Hän, and the Northern Tutchone. There is currently controversy over whether possible future oil drilling on the coastal plains of the Arctic National Wildlife Refuge, encompassing much of the Porcupine caribou calving grounds, will have a severe negative impact on the caribou population or whether the caribou population will grow.