Baby it’s warm outside. Climate change brings a slay for reindeer.

A cull of a quarter of a million reindeer has been proposed in northern Siberia by Christmas, in a bid to reduce the risk of an anthrax outbreak. This follows the death of a 12 year-old boy in the Arctic Circle this July after consuming the venison of an infected reindeer. The so-called “zombie” disease is believed to have been resurrected due to unusually warm temperatures this summer thawing the carcass of an anthrax-infected reindeer which died over 70 years ago.

reindeer-cull

Figure 1: Western Siberia: Reindeer herders hit hard by anthrax outbreak Credit: Steve Morgan/New Scientist.

The boy was one of 72 nomadic herders hospitalised, 41 of whom were children, from the town of Salekhard, following the anthrax outbreak. The Siberian Times reported the death of some 2,350 reindeer as well as at least four dogs. Officials are now calling for a cull to take place to reduce reindeer numbers and halt the spread of infection through larger herds.

However, it seems that the real villain in this story may be climate change, as authorities believe that the outbreak was closely linked to the abnormally high temperatures experienced in the region over this year’s summer. These record-breaking temperatures melted deep layers of permafrost causing the carcass, which was home to the deadly bacteria, to rise to the surface of the mud as it thawed. This led to the spread of the disease across the tundra through contact with animals and people and dispersal through the wind.

Global warming melting dreams of a White Christmas?

Though, as seen in Salekhard, warmer temperatures cause the ice to melt, they also pose other problems for reindeer. A 16-year study in Svalbard, has found that warmer winter temperatures have brought more rain rather than snow. This means that when the temperatures then get cooler again, wet ground freezes and essentially becomes a huge ice rink. This poses serious issues for the reindeer as the lichen which they feed on becomes trapped beneath the ice.

Mr. Forbes, an expert on permafrost ecology from the University of Lapland, described these weather events that caused this increase in ice as “rain-on-snow”  [1]. Though it may seem counterintuitive for warmer weather to bring with it more ice, the increase in temperature means the region experiences rainfall in place of snow, which in turn freezes as a thick layer of ice [2].

reindeer-buried-in-snow

Figure 2: Tens of thousands of reindeer dead in the past decade, according to new research. Climate change is the likely culprit. Credit: University of Lapland/ Huffinton Post

Reindeer have hooves powerful enough to stamp through 3/4 of an inch of ice, allowing them access to nutritious plants beneath. However, recent increases in rainfall have meant that the ice is substantially deeper often reaching several inches of thickness. This means that even the sharpest of reindeer hooves are unable to penetrate [3]. Consequently, females are giving birth to stunted young and reindeer are essentially diminishing through starvation.

HELP WANTED: More reindeer needed to pull Santa’s sleigh

Reindeer are shrinking in size and this has nothing to do with pre-holiday dieting. According to new research by population ecologist Steve Albon, it’s becoming increasingly difficult for them to feed and survive extreme winters. Albon’s study found that reindeer had suffered a 10-12% drop in weight between 1994 and 2010, dropping from an average of 55kg to 49kg.

reindeer-feed

Figure 3: Wild reindeer forage for food in Svalbard. Arctic reindeer are becoming smaller due to the impact of climate change. Credit: Ben Birchall/The Guardian

As reindeer are pregnant during the harsher, cold winter months, they must forage for lichen under the now frozen rainwater. This renders the reindeer unable to feed, causing thousands to die, with the few females that do survive losing their foetus entirely, or giving birth to significantly smaller calves. According to the study published last month in ‘Biology Letters’, 61,000 reindeer starved to death in Siberia as a direct result of a rain-on-snow event between 2013 and 2014 [1].

“In the winter, over the 20 years we’ve been working there [Svalbard], the temperature has gone up 9 degrees Celsius. It’s more likely that you’ll get these periods where the temperatures go above freezing, and if there’s any precipitation, it later freezes,” Steve Albon, James Hutton Institute.

Though these rises in temperature have also increased food supplies in summer months, leading to a population boom in reindeer, the loss of access to lichen in harsh icy winters has meant that bigger herds are made up of far smaller and weaker reindeer.According to Albon, colder, drier winters would mean more food, increasing the early growth of the foetuses, which he believes dictates the rest of their lives [4].

It’s getting hot in here…

Warmer summers can add further complication, as increased temperatures in these months can lead to an abundance in food, meaning that reindeer are more likely to mate. This essentially results in their population growing despite the increasingly frequent, harsh ice-rink winters. Though it is clear that limited winter resources can explain the “shrinking” reindeer phenomenon, there are further obstacles for their populations to overcome.

reindeer-couple-use

Figure 4: Reindeer are more likely to mate in summer. Therefore, reindeer populations are growing despite ice-rink winters. Calves are weak and suffer shrinking effects. Credit: Andy Smith

Smaller reindeer are at a considerable disadvantage through the winter months, as they have a significantly higher metabolism than that of their regular-sized brethren, yet less food available for them to consume. Furthermore, if too many reindeer “shrink”, then this could jeopardise the entire herd. This is as reindeer populations with most adults weighing more than 50kg tend to increase. In contrast, if the majority of the reindeer are underweight, populations are likely to decline.

At present, it is difficult to fully understand how climate change is affecting reindeer population numbers. Researchers are waiting for those reindeer born in recent years to reach maturity to assess exactly how they have been impacted. However, a similar study presented earlier this week (12th December) at the British Ecological Society, has found that climate change appears to indeed be responsible for Russia’s shrinking reindeer populations.

Is shrinking really a growing issue?

The phenomenon of “shrinking” as a result of climate change isn’t a novel one. As the planet warms, we have observed bees, spiders and beetles shrink in the past [5]. There have also been recent reports of shrinking bison, salamanders and a number of other animals across the globe because of climate change. 

If climate change continues at current rates then problems such as those experienced by the reindeer will undoubtedly become more severe and spread to a much greater number of species.

References:

  1. Forbes, B. C., Kumpula, T., Meschtyb, N., Laptander, R., Macias-Fauria, M., Zetterberg, P., Verdonen, M., Skarin, A., Kim, K-Y., Boisvert, L. & Stroeve, J. C. (2016). Sea ice, rain-on-snow and tundra reindeer nomadism in Arctic Russia. Biology Letters, 12(11), 20160466.
  2. Koenigk, T., Caian, M., Nikulin, G., & Schimanke, S. (2016). Regional Arctic sea ice variations as predictor for winter climate conditions. Climate Dynamics, 46(1-2), 317-337.
  3. Bartsch, A., Kumpula, T., Forbes, B. C., & Stammler, F. (2010). Detection of snow surface thawing and refreezing in the Eurasian Arctic with QuikSCAT: implications for reindeer herding. Ecological Applications, 20(8), 2346-2358.
  4. Douhard, M., Loe, L. E., Stien, A., Bonenfant, C., Irvine, R. J., Veiberg, V., & Albon, S. (2016, October). The influence of weather conditions during gestation on life histories in a wild Arctic ungulate. In Proc. R. Soc. B (Vol. 283, No. 1841, p. 20161760). The Royal Society.
  5. Live Science. (2011) Animals Shrink as Earth Warms. Retrieved on 14/12/16 from http://www.livescience.com/16563-climate-change-shrinking-animals.html
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