The barren-ground caribou is a subspecies of the reindeer that is found mainly in the Canadian territories of Nunavut and the Northwest Territories, as well as in Kitaa, Greenland. It sometimes includes the similar-looking Porcupine caribou, in which case the barren-ground caribou is also found in Alaska. The barren-ground caribou is a medium-sized caribou, smaller and lighter-coloured than the boreal woodland caribou, with the females weighing around and the males around. However, on some of the smaller islands, the average weight may be less. The large migratory herds of barren-ground caribou take their names from the traditional calving grounds, such as the Ahiak herd, the Baffin Island herds, the Bathurst herd, the Beverly herd, the Bluenose East herd, the Bluenose West herd, the Porcupine herd and the Qamanirjuaq herd.
Range and population
In Canada about fifty percent of all caribou are barren-ground caribou. Like the Peary caribou, both the males and females have antlers. In general, during the summer, the coat of the caribou is brown, and much lighter in the winter. The neck and rump tend towards a creamy-white colour. However, the general colouration may differ depending on the region. The barren-ground caribou usually breeds in the fall and calves in June but may not drop their single calf until July. Usually the female gives birth away from the herd and if possible on a patch of snow. After birth, the female licks the calf clean and eats the tissues and the placenta. This may serve two purposes, to replace nutrients lost from birthing and to help remove the scent that would attract predators. The main food source is lichen, but they also feed on Cyperaceae and grasses along with twigs and mushrooms. Caribou have also been observed eating antlers and seaweed and licking salt deposits. There is some evidence to suggest that, on occasion, they also feed on small rodents such as lemmings, fish such as Arctic char and bird eggs. On the mainland of Canada, the animals may travel in herds of several thousand, but they move in smaller groups on the islands. They are migratory animals and may travel in a season. Some groups, such as those living on Victoria Island during the summer, migrate to the mainland in the fall after the sea ice has formed. At this time, the smaller groups may form into a larger herd and several hundred animals may be seen. Mainland barren-ground caribou herds move to coastal areas for part of each year, with the exception of the Beverly herd. The Beverly herd and the Qamanirjuaq herd fall under the auspices of the Beverly and Qamanirjuaq Caribou Management Board. The range of the Beverly herd spans the tundra from northern Manitoba and Saskatchewan and well into the Northwest Territories and Nunavut. In 1994 survey there were 276,000 caribou, an all-time record. According to a 2011 survey based on data collected using cutting-edge digital tools and fly-over visual surveillance, 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. Ross Thompson, executive director of the Beverly and Qamanirjuaq Caribou Management Board, explains the low calving rate mainly on habitat deterioration and disturbance with other factors contributing to the low growth rate – parasites, predation and poor weather. John Nagy, University of Alberta's wildlife biologist and researcher, argued that the Beverly herd was robust, not declining. He claimed the herd had moved their calving grounds "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." He based his findings on data collected from 510 barren-ground caribou tracked with satellite collars in the Northwest Territories and Nunavut from 1993 to 2009. The barren-ground caribou, one of several subspecies called tuktu in Inuinnaqtun/Inuktitut, and written as ᓇᐹᕐᑐᕐᑲᓐᖏᑦᑐᒥ ᑐᒃᑐ in Inuktitut syllabics, is a major food source for the Inuit, especially the Caribou Inuit bands living in the Kivalliq Region of present-day Nunavut. The major predator of barren-ground caribou is the Arctic wolf. Wolves may follow the herd for many miles. The caribou has poor eyesight and hearing, but is capable of outrunning the wolf.
Dolphin-Union caribou herd
The Dolphin-Union caribou herd, locally known as the island caribou, are a migratory population of barren-ground caribou that occupy Victoria Island in Canada's High Arctic and the nearby mainland. They are endemic to Canada. They migrate across the Dolphin and Union Strait from their summer grazing on Victoria Island to their winter grazing area on the Nunavut-NWT mainland in Canada. It is unusual for North American caribou to cross sea ice seasonally and the only other caribou subspecies to do so is the Peary caribou, who are smaller in size and population.
Environmental threats
Climate change
In 2004 the Canadian Government's Species at Risk registry placed barren-ground caribou under the status of "special concern". Their status was a result of climate change having a negative impact on the population. Changing climate conditions in the Arctic are predicted to threaten barren-ground caribou in the immediate future. The risks associated with climate change can impact feeding habits, access to food and quality of food, birthing rates and calf rearing, greater distance of migration, thinning ice during migration and insect disturbances.
Food sources
Climate change negatively impacts barren-ground caribou's access to food. Extreme weather conditions can cause increased amounts of rain and freezing rain during winter months. This results in an ice layer which blocks access to lichen, the caribou's main food source. Frozen feeding grounds during winter months results in greater energy expenditure as the caribou attempt to access the lichen locked beneath the ice. This can result in malnutrition, starvation and death. Research has shown that changes in climate can alter the quality of lichen in the Arctic, making it less nutritious. A changing climate also introduces the threat of foreign plant species to the region, creating competition.
Calving season
Barren-ground caribou have evolved to match their calving period with the period in which lichen has traditionally bloomed. The phenological process and timing between birthing and easily accessible lichen is critical to the survival rate of the subspecies. The trophic mismatch, due to abnormal temperature variations linked to climate change, have resulted in malnutrition in their young, as well as reduced reproductive rates contributing to population decline.
Effects on migration
The timing of migration periods is closely linked to seasonal changes and as unpredictable climate conditions increase, barren-ground caribou must migrate over larger distances. Migration is dictated by the access to easily available lichen. An increased distance of migration places further stress and energy expense on the caribou. Warming weather conditions reduce ice thickness over rivers and lakes, making it difficult for caribou to cross. The reduced ice cover creates a natural barrier, which fragments the migration habitat and creates obstacles, preventing caribou from accessing annual feeding and breeding grounds. Unpredictable migration patterns also have negative impacts on Indigenous communities who depend on caribou as a source of income and food.
Insect harassment
An additional stressor on barren-ground caribou is the irritation from insect behaviour, which can dictate the movement and health of caribou during the summer months. Increased warming temperatures and early springs result in greater insect numbers. Insect harassment force caribou to migrate to areas which may still be covered in snow or ice, thereby reducing access to food. Caribou give birth in early spring when insect populations are low, to enable sufficient rearing of healthy and strong calves. Early onset of spring temperatures in the Arctic further effect the phenology of the pregnancy time periods of barren-ground caribou. Insect avoidance forces caribou to expend large amounts of energy through migrational avoidance of insects. Changes in the climate can increase parasitic occurrences, thereby providing an additional threat to the subspecies.
