How Caribou Are Affected by Climate Change in the Arctic


This blog post will discuss how climate change in the Arctic is affecting caribou, or reindeer. Caribou and reindeer are the same animal by the scientific name of Rangifer tarandus ( This species is a part of the deer family. In Europe and Asia, they are called reindeer. They are also called reindeer in North America only if they are domesticated. They are called Caribou in North America if they are wild. Throughout this blog post, I will be referring to them as Caribou.


Caribou are the only deer species where both males and females grow antlers. They also have the biggest and heaviest antlers out of all other deer species. The antlers of a male measure up to 51 inches long and the antlers of a female measure up to 20 inches long ( The antlers of these animals will shed and return larger every year. Males lose their antlers in November and they will come back in the spring. Females have their antlers through the winter and lose them in May when their calves are born. Male caribou weigh an average of 350-400 pounds, but weights of up to 700 pounds have been recorded. Females weigh an average of 175-225 pounds. They have large, wide hooves to support them in the Arctic tundra (Alaska Department of Fish and Game).


Caribou can be found in the Arctic tundra and surrounding forests of Greenland, Scandinavia, Russia, Alaska, and Canada. There are two ecotypes of Caribou. An ecotype is a distinct form of an animal species in a particular type of habitat. There are tundra caribou and forest caribou. Tundra caribou are more plentiful in population and migrate in large herds of up to half a million between tundra and forest areas ( Tundra caribou is the type of caribou that is most affected by climate change and will be the main focus of this blog.

Reindeer herd, Canada © Peter Ewins / WWF-Canada 


The diet of caribou consists of the leaves of willows, sedges, flowering tundra plants, and mushrooms in the summer months from May to September. In the winter months, they switch to lichen, often called reindeer moss, dried sedges, and small shrubs (Alaska Department of Fish and Game).

Climate Change

Caribou are mainly becoming affected by climate change through their food, especially during the winter months. Climate change is leading to milder winters in the Arctic region which means that there will be more rain often occurring in the winter rather than snow. In the winter, caribou search for and rely on their main staple foods: lichen and moss which are found buried under the snow. Because of climate change, caribou are having a difficult time getting to their food in the winter. More rainfall in the winter in the Arctic region is causing a thick layer of ice to form over their food ( Their food is now becoming buried under ice instead of snow. They can no longer access their main sources of food in the winter months. This has been causing wide starvation and death across the caribou population.

Warmer than average temperatures in the summer and fall will lead to increased mortality rates in caribou, especially young calves. Caribou have a layer of heavy insulation all year round and few sweat glands. Caribou are built and adapted to live in cold weather, not warm. Increased temperatures could cause a large decrease in population. In addition, rapid change in climate and variability in weather patterns could cause a reduction in the weight of caribou, thus decreasing the resilience of the population (

Caribou are a type of species that migrate back and forth between winter habitats and birthing habitats. They often cover a distance of 3,000 miles ( Climate change could cause these animals to have a difficult time migrating. Melting permafrost and ice loss will block their migration route. They have the possibility of drowning as they migrate.

Caribou populations around the Arctic have been rapidly decreasing. According to BBC News, the Arctic caribou population has fallen by more than half in the last 20 years. The number of caribou in the Arctic has decreased from 5 million to 2.1 million. This information was released at the American Geophysical Research Union meeting. They conducted a report called the 2018 Arctic Report Card, revealing the fact that weather and vegetation changes are making the Arctic less of a favorable habitat for caribou. This report stated that some herds of caribou have shrunk by more than 90% (BBC News, 2018). The chart below shows the maximum populations for each herd of caribou as the light gray bar and shows where the current populations of each herd are in the black bar. Most regions, or herds or caribou have decreased in population. Herds such as the George River, found in northeastern Canada and Taimyr, found in northern Russia, have seen the most decrease in caribou.

This map shows locations of 23 major reindeer herds, and the graph shows current population figures. NOAA Adapted from 2018 Arctic Report Card, Published December 11, 2018

Caribou also face the threat of increased parasites and diseases due to warmer temperatures. There are two types of flies named the warble flies and nose botflies that will lay their eggs in the caribou. There are also concerns of new parasites and diseases becoming introduced to Arctic caribou from other animals that could be living closer to them due to climate change such as the white tailed deer and moose (Northern Caribou Canada).

Works Cited

McCullough, Rebecca. “Climate Change Threatens Reindeer and Arctic People.” Climate Institute,,reduced%20food%20supply%20for%20reindeer.

Medicine, Center for Veterinary. “Fun Facts about Reindeer and Caribou.” U.S. Food and Drug Administration, FDA, 13 Feb. 2020,,reindeer%20if%20they%20are%20domesticated.

“Reindeer.” Encyclopedia Britannica, Encyclopedia Britannica, Inc.,

Caribou Species Profile, Alaska Department of Fish and Game,,(like%20blueberry)%20in%20September.

“11 Arctic Species Affected by Climate Change.” WWF,

Gill, Victoria. “Climate Change: Arctic Reindeer Numbers Crash by Half.” BBC News, BBC, 12 Dec. 2018,

Sullivan, Cody. “2018 Arctic Report Card: Reindeer and Caribou Populations Continue to Decline.” 2018 Arctic Report Card: Reindeer and Caribou Populations Continue to Decline | NOAA,

“Climate Change.” Northern Caribou – Climate Change,

Additional Links

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