Reindeer have developed adaptations for optimal metabolic efficiency during warm months as well as for during cold months. [155] 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 10kg (22lb) 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 3kg (6.6lb). After this, however, non-breeding females on average have a higher body fat mass than do breeding females. [156] 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." [147] 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. [198] Conservation [ edit ] Current status [ edit ] a b c d e 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. Kolpasсhikov, L.; Makhailov, V.; Russell, D. E. (2015). "The role of harvest, predators, and socio-political environment in the dynamics of the Taimyr wild reindeer herd with some lessons for North America" (PDF). Ecology and Society. 20. doi: 10.5751/ES-07129-200109. head of Moose Pass branch of the Smoky River, Alberta (north-east of Mount Robson)”; USNM No. 174505

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 peoples, Alaska Natives, and the Kalaallit of Greenland, caribou is an important source of food, clothing, shelter and tools. In 2011, noting that the former classifications of Rangifer tarandus, either with prevailing taxonomy on subspecies, designations based on ecotypes, 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, [35] an adaptation of "evolutionary significant units". [79] The 12 designatable units for caribou in Canada (that is, excluding Alaska and Greenland) based on ecology, behavior and, importantly, genetics (but excluding morphology and archaeology) essentially followed the previously-named subspecies distributions, without naming them as such, plus some ecotypes. Ecotypes are not phylogenetically based and cannot substitute for taxonomy. [80] Reindeer cows are the only female deer to grow antlers, which they use to defend food in patches of cleared snow. Another secret weapon in freezing environments: the nose. (Getty Images) Rudolf the Red-Nosed Reindeer - how reindeer became associated with Christmas Largest of the caribou, exceeding in measurements the largest specimens of Rangifer osborni and Rangifer montanus."Flying reindeer had long been the subject of shamanic tales amongst nomadic tribes in places like Mongolia and the Altai Mountains. Three-thousand year old standing stones placed above ancient burial grounds have carvings that depict reindeer in flight. Ancient Deer Stones in Mongolia depict flying reindeer. (Getty Images) What do reindeer eat? While Rangifer is a widespread and numerous genus in the northern Holarctic, being present in both tundra and taiga (boreal forest), [162] by 2013, many herds had "unusually low numbers" and their winter ranges in particular were smaller than they used to be. [18] Caribou and reindeer numbers have fluctuated historically, but many herds are in decline across their range. [174] This global decline is linked to climate change for northern migratory herds and industrial disturbance of habitat for non-migratory herds. [175] Barren-ground caribou are susceptible to the effects of climate change due to a mismatch in the phenological process between the availability of food during the calving period. [158] [176] [177] Main article: Reindeer herding A team pulling a sled near Arkhangelsk, Russia, late 19th-century photochrom Milking in Western Finnmark, Norway, 19th century a b c "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) Ernest S. Burch Jr. (1972). "The Caribou/Wild Reindeer as a Human Resource". American Antiquity. 37 (3): 339–368. doi: 10.2307/278435. JSTOR 278435. S2CID 161921691. 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. [9] Species and subspecies [ edit ] Extant species and subspecies of Rangifer Species

United States Food and Drug Administration (FDA) (13 December 2022). "Fun Facts about Reindeer and Caribou". Food and Drug Administration. 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. [154] Biology and behaviors [ edit ] Seasonal body composition [ edit ] Sweden DNA also revealed three unnamed clades that, based on genetic distance, genetic divergence and shared vs. private haplotypes and alleles, together with ecological and behavioral differences, may justify separation at the subspecies level: the Atlantic-Gaspésie caribou (COSEWIC DU11), [76] [64] an eastern montane ecotype of the boreal woodland caribou, and the Baffin Island caribou. [87] Neither one of these clades has yet been formally described or named. Kholodova, M.V.; Kolpashchikov, L.A.; Kuznetsova, M.V.; Baranova, A.I. (2011). "Genetic diversity of wild reindeer ( Rangifer tarandus) of Taimyr: analysis of polymorphism of the control region of mitochondrial DNA". Biology Bulletin. 38: 42–49. doi: 10.1134/S1062359011010067. S2CID 9180267.a b 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. London, U.K.: International Trust for Zoological Nomenclature. 1958. pp.337–338. Aldrovandi, U. (1621) Quadrupedum omnium bisulcorum historia. Bononiæ. Cap. 30: De Tarando– Cap. 31: De Rangifero. Wild reindeer "may well be the species of single greatest importance in the entire anthropological literature on hunting." [6] Meldgaard, M. (1986). "The Greenland caribou - zoogeography, taxonomy and population dynamics". Kommissionen for Videnskabelige Undersagelser i Grønland, Meddelelser om Grønland, Bioscience. 20: 1–88.

Additionally, as carrion, reindeer may be scavenged opportunistically by red and Arctic foxes, various species of eagles, hawks and falcons, and common ravens. 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; [222] 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. [223] 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; [224] Rozhkov et al. 2020 [225]).About 25,000 mountain reindeer ( R. t. tarandus) still live in the mountains of Norway, notably in Hardangervidda. [15] In Sweden there are approximately 250,000 reindeer in herds managed by Sami villages. [16] Russia manages 19 herds of Siberian tundra reindeer ( R. t. sibiricus) that total about 940,000. [17] The Taimyr herd of Siberian tundra reindeer is the largest wild reindeer herd in the world, [18] [19] varying between 400,000 and 1,000,000; it is a metapopulation consisting of several subpopulations — some of which are phenotypically different [20] — with different migration routes and calving areas. [21] [22] 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 Chukotka populations of R. t. sibiricus. [23] Siberian tundra reindeer herds have been in decline but are stable or increasing since 2000. [17]