Reindeer distribution

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.[20] In 2018 there were three left;[21] 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.

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,[22][18] 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. [23] Phylogenetic analysis shows that Grant's caribou clusters separately from all other Alaskan caribou[24] and does not interbreed with nearby caribou ecotypes.[25]

Male Porcupine caribou (R. t. groenlandicus) in Alaska, 2005 or earlier

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).[26] The Porcupine herd's annual migrations of 1,500 miles (2,400 km) are among the longest of any terrestrial mammal.[27] Its range spans approximately 260,000 km² (64,000,000 acres), 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;[28] see Reindeer: Taxonomy) 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.[29][30] 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.[31] 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.

Unlike many other barren-ground caribou, the Porcupine caribou is stable at relatively high numbers, but the 2013 photo census was not counted by January 2014. The peak population in 1989 of 178,000 animals was followed by a decline by 2001 to 123,000. By 2010, it recovered to 169,000.[32][26]

Many Gwich'in people, who depend on the Porcupine herd, still follow traditional caribou management practices that include a 1981 prohibition against selling caribou meat and limits on the number of caribou to be taken per hunting trip.[33]

A large bull reindeer in Alaska, 2006 or earlier

The Western Arctic caribou herd is the largest of the three Alaskan barren-ground caribou herds. The Western Arctic herd reached a low of 75,000 in the mid-1970s. In 1997 the 90,000 WACH changed their migration and wintered on Seward Peninsula. Alaska's reindeer herding industry has been concentrated on Seward Peninsula ever since the first shipment of reindeer was imported from eastern Siberia in 1892 as part of the Reindeer Project, an initiative to replace whale meat in the diet of the indigenous people of the region.[34] For many years it was believed that the geography of the peninsula would prevent migrating caribou from mingling with domesticated reindeer who might otherwise join caribou herds when they left an area.[34][35] In 1997, the domesticated reindeer joined the Western Arctic caribou herd on their summer migration and disappeared.[36] The WACH reached a peak of 490,000 in 2003 and then declined to 325,000 in 2011.[37][38]

_{Prudhoe Bay Oil Field}

_{Teshekpuk Lake}

North Slopes, Alaska

In 2008, the Teshekpuk Lake caribou herd had 64,107 animals and the Central Arctic caribou herd had 67,000.[39][40]

By 2017, the Teshekpuk herd's numbers, whose calving grounds are in the region of the shallow Teshekpuk Lake,[41] had declined to 41,000 animals.[41] Teshekpuk Lake in the North Slope is in the traditional lands of the Iñupiat, who depended on the Teshekpuk herd for millennia. Teshekpuk Lake is also in the National Petroleum Reserve-Alaska, where the U.S. Department of the Interior (DOI) had approved oil and gas drilling on 11 January 2006.[42][43] The NPR-A is the "single largest parcel of public land in the United States" covering about 23 million acres". The reserve's eastern border sits about 100 miles to the west of the more famous Arctic National Wildlife Refuge. The leasing of Teshekpuk Lake land to industry was protested by the Iñupiat and others who sent 300,000 letters to the US Secretary of the Interior and the ConocoPhillips CEO over the summer of 2006. On 25 September 2006, the U.S. District Court for the District of Alaska protected the wildlife habitat around the lake from an oil and gas lease sale.[44]

In October 2017, U. S. Secretary of the Interior, Ryan Zinke, announced that as of 6 December 2017, lands under the administration of the U.S. Bureau of Land Management will be up for bid on the "largest offering of public lands for lease in the history of the [BLM] — 10.3 million acres".[41] The Prudhoe Bay Oil Field, near Prudhoe Bay, Alaska, is situated between the Arctic National Wildlife Refuge to the east. Industry will be allowed to run "roads, pipelines and drill rigs" in the very sensitive habitat areas, including the Teshekpuk caribou herd calving grounds. The Teshekpuk herd remains at the calving grounds for several weeks in spring before moving from Teshekpuk Lake for relief from mosquitoes and botflies before their annual migration.[41]

Reindeer were imported from Siberia in the late 19th century and from Norway in the early 1900s as semi-domesticated livestock in Alaska.[45][46] Reindeer can interbreed with the native caribou subspecies, but they rarely do, and even then their offspring do not survive well in the wild.[47][25]

The barren-ground caribou (R. t. groenlandicus),[48] a long-distance migrant, includes large herds in the Northwest Territories and in Nunavut, for example, the Beverly, the Ahiak and Qamanirjuaq herds. In 1996, the population of the Ahiak herd was approximately 250,000 animals.

The Ahiak, Beverly and Qamanirjuaq caribou herds are all barren-ground caribou.

The Beverly herd of barren-ground caribou, Thelon River, Nunavut, 1978.[49]

"The Beverly herd’s crossing of the Thelon River to its traditional calving grounds near Beverly Lake was part of the lives of the Dene aboriginal people for 8,000 years, as revealed by an unbroken archaeological record of deep layers of caribou bones and stone tools in the banks of the Thelon River (Gordon 2005)."[50][51] The Beverly herd (located primarily in Saskatchewan, Northwest Territories; with portions in Nunavut, Manitoba and Alberta) and the Qamanirjuaq Herd (located primarily in Manitoba, Nunavut; with portions in the southeastern NWT and northeastern Saskatchewan) fall under the auspices of the Beverly and Qamanirjuaq Caribou Management Board.[52] The Beverly herd, whose range spans the tundra from northern Manitoba and Saskatchewan and well into the Northwest Territories and Nunavut, had a peak population in 1994 of 276,000[53][54] or 294,000,[13] but by 2011 there were approximately 124,000 caribou in the Beverly herd and 83,300 in the Ahiak herd. The calving grounds of the Beverly herd are located around Queen Maud Gulf, but the herd shifted its traditional birthing area.[55] Caribou management agencies are concerned that deterioration and disturbance of habitat along with "parasites, predation and poor weather"[53] are contributing to a cycling down of most caribou populations. It was suggested the Ahiak and Beverly herds switched calving grounds and the Beverly may have moved "near the western Queen Maud Gulf coast to the north of the herd’s "traditional" calving ground in the Gary Lakes area north of Baker Lake."[56] The "Beverly herd may have declined (similar to other Northwest Territories herds), and cows switched to the neighbouring Ahiak herd to maintain the advantages of gregarious calving."[57] By 2011 there were approximately 124,000 caribou in the combined Beverly/Ahiak herd which represents a "50% or a 75% decline from the 1994 population estimate for the Beverly Herd."[13]

The barren-ground caribou population on Southampton Island, Nunavut declined by almost 75%, from about 30,000 caribou in 1997 to 7,800 caribou in 2011.[13][58]

The Peary caribou (R. t. pearyi) is a relatively small and pale subspecies found in the tundra of far northern North America. Unsurprisingly, it is part of the group known as tundra reindeer.

The Peary caribou (R. t. pearyi), the smallest subspecies in North America, known as tuktu in Inuktitut, are found in the northern islands of Nunavut (except Baffin Island) and the Northwest Territories. They remain at low numbers after severe declines.

A population of barren-ground caribou (R. t. groenlandicus) summers on Victoria Island and crosses the ice of Dolphin and Union Strait to the lands around Coronation Gulf for winter. Once thought to be hybrids or intergrades with Peary caribou, they are now known to be a barren-ground caribou named after the strait that they migrate across: Dolphin-Union caribou. Further research showed that some R. t. pearyi x groenlandicus hybrids occur on Banks Island and the northwest corner of Victoria Island.[59]

On Baffin Island, the largest Arctic island, the population of barren-ground caribou (R. t. groenlandicus) peaked in the early 1990s to approximately 60,000 to 180,000.[60] By 2012, in northern Baffin Island caribou numbers were considered to be at a "low in the cycle after a high in the 1990s" and in southern Baffin Island, the population was estimated as between 1,065 and 2,067.[61] Baffin Island caribou are highly divergent from other barren-ground caribou,[62] have a different mating system, lack migratory and aggregation behaviors, and have morphological differences.[63]

There are four barren-ground caribou herds in the Northwest Territories—the Cape Bathurst, Bluenose West, Bluenose East and Bathurst herds.[13] The Bluenose East caribou herd began a recovery with a population of approximately 122,000 in 2010,[64] which is being credited to the establishment of Tuktut Nogait National Park.[65] According to T. Davison 2010, CARMA 2011, the three other herds "declined 84–93% from peak sizes in the mid-1980s and 1990s.[13]

The Committee on Status of Endangered Wildlife in Canada (COSEWIC) [66] divided woodland caribou (R. tarandus caribou) ecotypes into five "Designatable Units" (DU) as noted above. Caribou are classified by ecotype depending on several behavioral factors – predominant habitat use (northern, tundra, mountain, forest, boreal forest, forest-dwelling), spacing (dispersed or aggregated) and migration patterns (sedentary or migratory).[67][68][69]

In Canada, the national meta-population of the sedentary boreal woodland ecotype spans the boreal forest from the Northwest Territories to Labrador. They prefer lichen-rich mature forests[70] and mainly live in marshes, bogs, lakes and river regions.[71][72] The historic range of the boreal woodland caribou covered over half of present-day Canada,[73] stretching from Alaska to Newfoundland and Labrador and as far south as New England, Idaho and Washington. Woodland caribou have disappeared from most of their original southern range and only about 34,000 remain.[74] The boreal woodland caribou was designated as threatened in 2002.[75]

The migratory George River caribou herd (GRCH), in the Ungava region of Quebec and Labrador in eastern Canada was once the world's largest caribou herd with 800,000–900,000 animals. It is a herd of Labrador caribou, Rangifer tarandus caboti.[48] The GRCH is the migratory woodland caribou and, like the barren-ground caribou, its ecotype may be tundra caribou, Arctic, northern or migratory, not forest-dwelling and sedentary like most woodland caribou ecotypes. It is unlike most woodland caribou in that it is not sedentary. Since the mid-1990s, the herd declined sharply and by 2010, it was reduced to 74,131—a drop of up to 92%.[76] A 2011 survey confirms a continuing decline of the George River caribou herd population. By 2018 it was estimated to be fewer than 9,000 animals as reported by the Canadian Broadcasting Corporation, down from 385,000 in 2001 and 74,131 in 2010.[11][76][77]

Leaf River caribou herd

Caribou crossing Leaf River

The Leaf River caribou herd (LRCH),[78] another migratory herd of Labrador caribou, near the coast of Hudson Bay, increased from 270 000 individuals in 1991 to 628 000 in 2001.[79] By 2011 the herd had decreased to 430 000.[11][76][80] According to an international study on caribou populations, the George River and Leaf River herds and other herds that migrate from Nunavik, Quebec and insular Newfoundland, could be threatened with extinction by 2080.[77]

The Queen Charlotte Islands caribou (formerly R. t. dawsoni) from Graham Island, the largest of the Queen Charlotte Islands, is a distinct subspecies.[15] It became extinct at the beginning of the 20th century. Recent DNA analysis from mitochondrial DNA taken from the remains of these caribou suggest that the animals from the Queen Charlotte Islands were genetically close to from the adjacent mainland caribou subspecies,[81] Osborn's caribou, now recognized as of Beringian-Eurasian lineage.[82]

Characteristically small and relatively short-legged reindeer from Svalbard

The Svalbard reindeer (R. tarandus platyrhynchus) from Svalbard Island is very small compared to other subspecies (a phenomenon known as insular dwarfism) and is the smallest of all the subspecies, with females having a length of approximately 150 cm (59 in), and a weight around 53 kg (117 lb) in the spring and 70 kg (150 lb) in the autumn.[90] Males are approximately 160 cm (63 in) long, and weigh around 65 kg (143 lb) in the spring and 90 kg (200 lb) in the autumn.[90] The reindeer from Svalbard are also relatively short-legged and may have a shoulder height of as little as 80 cm (31 in),[90] thereby following Allen's rule.

Svalbard reindeer (R. t. platyrhynchus)

The Svalbard reindeer seems to have evolved from large European reindeer,[91] and is special in several ways: it has peculiarities in its metabolism, and its skeleton shows a remarkable relative shortening of the legs, thus parallelling many extinct insular deer species.[92]