Climate change

Changes in climate are often cited as major threats to the future of Arctic caribou. Some change has already been observed, such as an increase in wildfires, earlier snowmelt and later onset of winter, changes in the formation of ice, and warmer temperatures. Future changes are not projected to be the same across the range of Arctic caribou in Canada, but all parts of the range are expected to see at least some further changes in the coming decades. The ways in which climate change is expected to affect caribou vary, and are listed below.

Changes to food

Some studies suggest that earlier springs might be good for caribou as it will give them access to higher quality food earlier, making them more healthy at a time when they are giving birth and feeding their calves. However, this advantage might ultimately be balanced by changes in the kinds of food available to them. As the tundra warms, there is evidence that the kinds of plants that grow there are changing. More woody plants are beginning to replace grasses and flowering plants, and the woody plants are less nutritious for caribou.

While food may be more available to caribou in the summer, it may become less available in the winter. Ice is a particular problem when it forms on, in, or beneath the snow. There is predicted to be an increase in freeze-thaw events where caribou live. This is when temperatures hover around the freezing point, and some snow melts, then it freezes again. This creates layers of ice in the snow pack, layers that caribou must dig through to get at the food beneath. These sort of events can lead to worse body condition for caribou, leading in turn to fewer calves being born. In extreme cases, icing has been blamed for starving caribou to death.

Predicted increases in forest fires will likely also become important for the migratory caribou that move to the treeline for the winter. It has been shown that caribou mostly tend to avoid burnt-out areas. This is likely due in large part to the damage that forest fires do to lichens, a primary winter food source for the caribou. Lichens can take decades to recover to the point that there are enough mature clumps to attract caribou.

Parasites and diseases

Warmer weather is anticipated to lead to caribou being more bothered by two types of flies that lay their eggs in the caribou, warble flies and nose botflies. When the caribou are bothered by these sorts of flies, they will often try to escape by running around, or by finding a more windy spot or a patch of snow where the conditions reduce the numbers of flies. Longer summers are expected to lead to more opportunities for the flies to lay their eggs in the caribou. The caribou can be affected by either losing opportunities to feed and wasting energy while they try to escape the flies, or by the effects of having the eggs of the flies hatch, and the parasitic larvae of the flies weakening the caribou.

Apart from existing parasites, there are concerns that warmer weather will lead to new parasites and diseases in the caribou range, possibly brought in by other animals such as moose and white tailed deer moving further north. A parasite called Besnoitia tarandi started to be noticed in eastern migratory caribou around 2005 and is cited in the COSEWIC report on the caribou as a possible limitation to productivity. In 2010, caribou lungworm, a parasite previously limited to the mainland was reported in caribou on Victoria Island.  Climate change has been suggested as the likely cause of this northward movement of the lungworm. Chronic wasting disease, a disease that is hitting populations of wild deer in southern canada could potentially move north and infect caribou.

Changes to water and ice

The condition of ice is important to caribou as they use it for crossings during their migrations. caribou also cross open water when they must. The barren-ground caribou cross lakes and rivers. If the ice is not thick enough, or if water flows are too fast, caribou can drown.  In one notable event in 1984, an estimated 10,000 caribou from the George River herd died after being swept over a waterfall in Nunavik (Northern Quebec). 

The Dolphin and Union herd and Peary caribou cross sea ice. The Dolphin and Union herd is particularly vulnerable to changes in sea ice as it migrates across the ice twice a year, from Victoria Island to the mainland and back again. There have been several reports of caribou from this herd drowning, or freezing to death after falling through the ice or crossing open water.

Related news

Hunting restrictions imposed after another Nunavut caribou herd dwindles

This news story talks about hunting restrictions being placed on the Dolphin and Union herd in Nunavut. The unique herd that migrates between the Victoria island and the mainland saw its population drop to about 4,000 in the last (2018) survey. The new quota allows people from local communities to take 42 caribou. Last year, just one community took as many as 200.
12 November 2020 | cbc north

Climate is changing Arctic wildlife habits; unique international study

This web story talks about a new study that looked at long term movement patterns in a variety of Arctic wildlife, including caribou. The story notes, "...there is evidence of earlier migrations to the north, and for example earlier births among northern caribou, not seen in more southerly herds. This may result in the higher mortality being observed in northern caribou herds as nutritious food may not be sprouting at the same time as migrations and calving."
6 November 2020 | Radio Canada International

New framework identifies climate change “refugia” in boreal forest

This magazine article talks about the idea of looking at what places in the northern boreal forest are least likely to change as climate change advances. Areas that change the least ('resilient' areas) are likely to be important for animals adapted to existing conditions such as caribou, so conserving these areas could be a priority.
25 June 2020 | Canadian Geographic

troubled tundra

A long magazine article on the future of the Arctic National Widlife Refuge in Alaska. The refuge is home to the calving grounds of the Porcupine caribou herd that migrates between the Northwest Territories, Yukon and Alaska. The refuge is threatened by a changing climate and by ongoing attempts to open it up for development.
24 June 2020 | earth island journal

The new north

Some great pictures of the Porcupine caribou migration here in this photo essay on the north's changing climate.
1 June 2020 | The Narwhal

Arctic caribou move up migration due to climate change

Story about how the Qamanirjuaq herd has moved up its northward migration dates in Nunavut in response to climate change 
4 May 2020 | St. Albert Today

Is Warming Bringing a Wave of New Diseases to Arctic Wildlife?

Rapid warming and vanishing sea ice in the Arctic has enabled new species, from humpback whales to white-tailed deer, to spread northward. Scientists are increasingly concerned that some of these new arrivals may be bringing dangerous pathogens that could disrupt the region’s fragile ecosystems.
6 November 2018 | Yale 360

Across Canada, caribou are on course for extinction, a prominent expert warns. What happens after that?

While the threats caribou face are complex and vary by region, the common denominator is human activity, primarily through resource development and, increasingly, climate change.
29 October 2018 | Globe and Mail

Related resources

study on advancing migration, calving dates for Qamanirjuaq caribou

This academic study says Qamanirjuaq caribou are migrating and calving earlier, matching earlier greening uo of calving grounds. The authors think this may show caribou are more resilient to climate change.
(2020)

caribou and sea ice crossings near Gjoa Haven

This is part of a project website (www.straightupnorth.ca) for community-based research in Inuit Nunangat (areas where Inuit live in Canada). The caribou project looked at caribou's use of ice crossings near Gjoa Haven, Nunavut, and how changing sea ice conditions and ship traffic could affect those crossings.
(2020)

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Format: web

Range managementClimate changeHuman disturbance

Renal trace elements in barren-ground caribou subpopulations: Temporal trends and differing effects of sex, age and season

An academic paper that looks at the level of some metals in kidneys of some northern caribou. It found that copper levels are decreasing in the caribou kidneys, possibly due to changes in what caribou are eating. The paper concludes, "Declining Cu concentrations in caribou are of concern as low levels could potentially negatively affect reproduction and therefore caribou at a population level."
Science of the Total Environment (2020)

Biotic interactions govern the distribution of coexisting ungulates in the Arctic Archipelago – A case for conservation planning

An academic paper looking at what might best predict habitat for Peary caribou and muskox in the Canadian Arctic Archipelago. the paper models what it considers likely key habitat for both species in late winter, and notes that most of this habitat is outside of protected areas.
(2020)

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PearyRange managementClimate change

Merging indigenous and scientific knowledge links climate with the growth of a large migratory caribou population

This academic paper collected both scientific and traditional knowledge inputs about the state of the Porcupine caribou herd over ten years. The study "...indicates that a large migratory caribou population can grow and improve condition in a global context of caribou decline and climate warming, thereby warning against generalizations about the influence of climate on all caribou populations."
(2020)

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PorcupineClimate change

Ecological insights from three decades of animal movement tracking across a changing Arctic

This academic article summarizes trends in long-term data on a variety of Arctic species movements, including barren-ground Caribou. It found, "Barren-ground caribou calved later despite occupying a similar latitudinal range as the northern boreal caribou (Fig. 3). Most importantly, barren-ground and northern woodland caribou, but not southern woodland caribou, exhibited significant trends toward earlier parturition [0.4 to 1.1 days/year (table S10)]. This is the first continental-scale retrospective evidence of potential adaptive responses to climate trends by caribou."
science magazine (2020)

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Barren-groundClimate change

Population Estimate of the Dolphin and Union Caribou herd (Rangifer tarandus groenlandicus x pearyi) Coastal Survey, October 2018 and Demographic Indicators

This 49 page (in English) report contains executive summaries in Inuktitut (both syllabics and western orthography). It shows that the Dophin and Union herd has declined to an estimated 4,105 in 2018, down from 17,000 in 2015. The Dophin and Union herd is unique, being neither barren-ground nor Peary caribou. It migrates between Victoria Island and the mainland. 
Government of Nunavut (2020)

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Format: pdf

Dolphin and UnionClimate changeHunting

Tactical departures and strategic arrivals: Divergent effects of climate and weather on caribou spring migrations

A 2019 academic paper that looks at factors affecting caribou migration timing and speed. The paper concludes that  later arrival at calving grounds might indicate that females are in worse condition, and that calving and calf survival rates might be lower.
(2019)

Technical Report on Cape Bathurst, Bluenose-West and Bluenose-East Caribou Herds

A 90-page 2016 report presenting scientific knowledge and status of the Cape Bathurst, BluenoseWest and Bluenose-East caribou herds and gaps in knowledge.  One of two companion documents to "Taking Care of Caribou: The Cape Bathurst, Bluenose-West and Bluenose-East Caribou Herds Management Plan"
Government of the Northwest Territories (2016)

Engaging Bluenose Caribou Communities

This lengthy 2014 report contain notes from all the community meetings that fed into the management plan for three herds (Bluenose-East and West and Cape Bathurst). It is the result of consultation sessions in 17 communities in the NWT and Nunavut. It contains much Indigneous knowledge about the caribou, but the report cautions that it “...should not be seen as a complete record of the traditional and community knowledge that exists about these caribou.”
Wekʼèezhìi Renewable Resources Board (WRRB) (2014)

Working together for Baffin Island Caribou

A brief 2013 workshop report which examines the causes and impacts of the decline of caribou on Baffin Island, and suggests some management measures.
Government of Nunavut (2013)