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ABOUT THE REINDEER PROJECT

The leading organization for collecting research about Arctic climate change and the effects it has on reindeer.

CLIMATE CHANGE.

Image by Markus Spiske

FORAGING.

It's no secret that the climate is changing. Surface temperatures are increasing rapidly across the globe, which affects precipitation and vegetation distributions worldwide. According to polar amplification, these changes in temperature are experienced in excess in the polar regions. Climate change at the Equator does not produce the same drastic effects that it does at the poles. In the Arctic, this leads to increases in permafrost temperatures and decreases in sea ice extent and snow cover, among many other things.¹ When considered independently, these variables may not seem like a huge deal. The fact is, even just one degree of temperature fluctuation or two fewer days of sea ice cover per year can have massive effects on the Arctic ecological communities as a whole. But how does this affect reindeer? Keep reading below to see the string of events that snowball into a much bigger issue for Arctic reindeer populations.

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One of the major effects of climate change on reindeer in the Arctic is the ability to and quality of forage. Warming temperatures increase how quickly the snow melts, which changes the timing of vegetation blooms and can also alter the vegetations nutritional value.² ³ Plant phenologies are changing with the climate, which interferes with and potentially inhibits reindeer ability to forage for food. If the vegetation is blooming sooner than they are used to, they may not time their migration to properly match optimal bloom time, which decreases reindeer ability to forage for the resources they need.⁴ 

 

On the subject of increasing precipitation from climate change, warmer and wetter winters decrease a reindeer's ability to forage.⁵ Oftentimes, rain will fall on top of the snow, which increases the hardness of the snow. This inhibits the reindeer's ability to "crater" through the snow and forage for food.⁶ Warming temperatures result in more frequent precipitation, which will only intensify the harmful effects of rain on snow events.⁷ 

A CASE STUDY: LICHENS AND OVERGRAZING.

Image by Kelly Sikkema

Reindeer across the board are dependent upon lichens during the winter months; they are a vital source of nutrients.⁸ In the winter when resources are relatively scarce, reindeer diets can consist of more than 50% lichens. There's not a lot of vegetation during this time, so lichens and shrubs are the main food sources. Since there's such an intense limit on the available resources, this often leads to rapid depletion of available foods.⁹ The lichens often do not have enough time to regenerate and reproduce, and it can take decades for a lichen community to return to its initial state after heavy grazing by reindeer.¹⁰

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Reindeer much prefer lichens to other foods, so much so that they will migrate to higher and higher latitudes in order to find them. Warming temperatures are pushing lichens more towards the poles so that they can remain in their optimal environment, and they are so important to reindeer that they will migrate alongside the plants.¹¹ In addition to this, warmer temperatures and increased levels of soil nutrients may lead to the replacement of lichens with more vascular plants.¹² When lichens are over grazed, this opens up the opportunity for graminoids (grasses and sedges) to replace the arctic moss.¹³ ¹⁴ Current warming trends are increasing shrub cover and decreasing lichen cover, which only increases the depletion of the reindeer's most preferred food source.¹⁵

REPRODUCTION.

Image by Sébastien Goldberg

Reindeer are heavily reliant upon body stores of proteins and fats during the wintertime since food resources are so scarce.¹⁶ With climate change affecting plant phenologies and decreasing accessibility, these body stores are not as effective. If the herd cannot successfully forage and find adequate food, their storages for the winter will suffer. A lack of food and resources weakens the herd of reindeer, which is especially harmful to females because they have to deal with reproduction.¹⁷ They are already going to experience deficiencies in their stores over the winter months, but then there is the issue of allocating portions of the storage to reproduction. Producing a calf increases energy and nutrient demands and if the stores are already depleted, there will not be enough proteins and fats to go towards fetal development and growth.¹⁸ It has been suggested that with warmer (and therefore wetter) winters, the survivability of calves decreases. Overall, climate change will reduce the number of healthy calves that will eventually reach adulthood, effectively reducing the species fitness.¹⁹ Given the chance, it's possible that females could adapt to time their allocation of proteins in relation to reproduction to align better with food availability and body stores, but the climate is changing much too rapidly for adaptations to be effective. 

GROWTH RATES.

Changing plant phenologies affect how nutritious the vegetation is for a reindeer's diet.²⁰ ²¹ If the plant community is changing, the new composition could potentially be far less nutritious than the herds current diet.²² If they are not obtaining the proper nutrients from their food sources, their bodies will become stressed and their growth rates will suffer. This also loops back to reproduction. If the calves are not increasing their body mass and getting the proper nutrients that they need to grow, they will have trouble producing the next generation of reindeer. Additionally, it has been proven that lichens may restrain calf growth. The digestibility of the vegetation increases with age, but in younger reindeer it can do more harm than good. Fully grown reindeer do not need grow and gain weight the same way that calves do, so the lichens do not pose as much of an issue. Even though it's one of their favorite foods, the Arctic moss is fairly mineral limited and therefore does not provide them with all of the nutrients to support healthy body mass and weight gain.²³ 

CONCLUSIONS.

Reindeer populations are in a constant state of decline.²⁴ While this could be due to a variety of different factors, it's clear that the changing climate is playing a role. Warming temperatures are hurting the environment, and they're hurting the surrounding ecosystems too. If we aren't careful with our current behavior, these trends will become even more severe, and we could lose one of the Arctic's most majestic species.

  1. Moritz, R. E. “Dynamics of Recent Climate Change in the Arctic.” Science, vol. 297, no. 5586, 2002, pp. 1497–1502., doi:10.1126/science.1076522.

  2. Cebrian, Merben R., et al. “Forage Quality and Reindeer Productivity: Multiplier Effects Amplified by Climate Change.” Arctic, Antarctic, and Alpine Research, vol. 40, no. 1, 2008, pp. 48–54., doi:10.1657/1523-0430(06-073)[cebrian]2.0.co;2.

  3. Heggberget, Thrine Moen, et al. “Reindeer (Rangifer Tarandus) and Climate Change: Importance of Winter Forage.” Rangifer, vol. 22, no. 1, 2002, p. 13., doi:10.7557/2.22.1.388.

  4. Vors, Liv Solveig, and Mark Stephen Boyce. “Global Declines of Caribou and Reindeer.” Global Change Biology, vol. 15, no. 11, 2009, pp. 2626–2633., doi:10.1111/j.1365-2486.2009.01974.x.

  5. Hansen, Brage Bremset, et al. “Climate, Icing, and Wild Arctic Reindeer: Past Relationships and Future Prospects.” Ecology, vol. 92, no. 10, 2011, pp. 1917–1923., doi:10.1890/11-0095.1.

  6. Heggberget, Thrine Moen, et al. “Reindeer (Rangifer Tarandus) and Climate Change: Importance of Winter Forage.” Rangifer, vol. 22, no. 1, 2002, p. 13., doi:10.7557/2.22.1.388.

  7. Hansen, Brage Bremset, et al. “Climate, Icing, and Wild Arctic Reindeer: Past Relationships and Future Prospects.” Ecology, vol. 92, no. 10, 2011, pp. 1917–1923., doi:10.1890/11-0095.1.

  8. Wal, René, et al. “Differential Effects of Reindeer on High Arctic Lichens.” Journal of Vegetation Science, vol. 12, no. 5, 2001, pp. 705–710., doi:10.2307/3236911.

  9. Heggberget, Thrine Moen, et al. “Reindeer (Rangifer Tarandus) and Climate Change: Importance of Winter Forage.” Rangifer, vol. 22, no. 1, 2002, p. 13., doi:10.7557/2.22.1.388.

  10. Joly, Kyle, et al. “Decrease of Lichens in Arctic Ecosystems: the Role of Wildfire, Caribou, Reindeer, Competition and Climate in North-Western Alaska.” Polar Research, vol. 28, no. 3, 2009, pp. 433–442., doi:10.1111/j.1751-8369.2009.00113.x.

  11. Hansen, Brage Bremset, et al. “Climate, Icing, and Wild Arctic Reindeer: Past Relationships and Future Prospects.” Ecology, vol. 92, no. 10, 2011, pp. 1917–1923., doi:10.1890/11-0095.1.

  12. Turunen, Minna, et al. “Does Climate Change Influence the Availability and Quality of Reindeer Forage Plants?” Polar Biology, vol. 32, no. 6, 2009, pp. 813–832., doi:10.1007/s00300-009-0609-2.

  13. Joly, Kyle, et al. “Decrease of Lichens in Arctic Ecosystems: the Role of Wildfire, Caribou, Reindeer, Competition and Climate in North-Western Alaska.” Polar Research, vol. 28, no. 3, 2009, pp. 433–442., doi:10.1111/j.1751-8369.2009.00113.x.

  14. Väisänen, Maria, et al. “Consequences of Warming on Tundra Carbon Balance Determined by Reindeer Grazing History.” Nature Climate Change, vol. 4, no. 5, 2014, pp. 384–388., doi:10.1038/nclimate2147.

  15. Maliniemi, Tuija, et al. “Long-Term Vegetation Changes of Treeless Heath Communities in Northern Fennoscandia: Links to Climate Change Trends and Reindeer Grazing.” Journal of Vegetation Science, vol. 29, no. 3, 2018, pp. 469–479., doi:10.1111/jvs.12630.

  16. Barboza, Perry S., and Katherine L. Parker. “Allocating Protein to Reproduction in Arctic Reindeer and Caribou.” Physiological and Biochemical Zoology, vol. 81, no. 6, 2008, pp. 835–855., doi:10.1086/590414.

  17. Lee, Susan E., et al. “Regional Effects of Climate Change on Reindeer: a Case Study of the Muotkatunturi Region in Finnish Lapland.” Polar Research, vol. 19, no. 1, 2000, pp. 99–105., doi:10.3402/polar.v19i1.6535.

  18. Barboza, Perry S., and Katherine L. Parker. “Allocating Protein to Reproduction in Arctic Reindeer and Caribou.” Physiological and Biochemical Zoology, vol. 81, no. 6, 2008, pp. 835–855., doi:10.1086/590414.

  19. Lee, Susan E., et al. “Regional Effects of Climate Change on Reindeer: a Case Study of the Muotkatunturi Region in Finnish Lapland.” Polar Research, vol. 19, no. 1, 2000, pp. 99–105., doi:10.3402/polar.v19i1.6535.

  20. Turunen, Minna, et al. “Does Climate Change Influence the Availability and Quality of Reindeer Forage Plants?” Polar Biology, vol. 32, no. 6, 2009, pp. 813–832., doi:10.1007/s00300-009-0609-2.

  21. Heggberget, Thrine Moen, et al. “Reindeer (Rangifer Tarandus) and Climate Change: Importance of Winter Forage.” Rangifer, vol. 22, no. 1, 2002, p. 13., doi:10.7557/2.22.1.388.

  22. Mallory, Conor D., and Mark S. Boyce. “Observed and Predicted Effects of Climate Change on Arctic Caribou and Reindeer.” Environmental Reviews, vol. 26, no. 1, 2018, pp. 13–25., doi:10.1139/er-2017-0032.

  23. Heggberget, Thrine Moen, et al. “Reindeer (Rangifer Tarandus) and Climate Change: Importance of Winter Forage.” Rangifer, vol. 22, no. 1, 2002, p. 13., doi:10.7557/2.22.1.388.

Klokov, Konstantin B. “Changes in Reindeer Population Numbers in Russia: an Effect of the Political Context or of Climate?” Rangifer, vol. 2, no. 1-App, 2013, p. 19., doi:10.7557/2.32.1.2234.

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