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22 December 2016

Average Size of Arctic Reindeer Shrinking

Climate change, harbinger of a plethora of other global problems, is affecting the overall size of reindeer residing on an Arctic island near the North Pole. A 16-year study determined that the average weight of an adult reindeer on Svalbard, a chain of islands north of Norway, fell from 121 lbs. (55 kilogram) in 1994 to 106 lbs. (48 kilogram) in 2010. The study was presented at the British Ecological Society meeting on 12 December. Reindeers have had a tough go of it, dropping 10 to 12% in weight in the past decade. Lead study researcher Steve Albon, an emeritus population ecologist at the James Hutton Institute in Scotland, attributes the loss to warmer winters and summers.

Generally, reindeer mate in late October and give birth in early June. In winter, reindeer root around in the snow in search of lichen, a slow-growing organism that’s part fungi and part algae, Albon said to Live Science. Mild winters of late, while great for humans, drastically limit the food available to herbaceous animals like the reindeer. Warmer ambient temperatures cause snowfall to be replaced by rain. The soaked ground freezes into a sheet of ice as soon as temperatures drop, making it near impossible to forage for lichen. From 2013 to 2014, 61,000 reindeer starved to death in Siberia due to “a rain-on-snow event” according to a study published in Biology Letters. The vastly limited food source has resulted in hundreds of starving reindeer. Pregnant females that survive will either birth stunted young or lose the foetus. According to Albon, “if the winter was cold and dry, the mothers could get to the food, and the calves would be born at size and likely to be more viable. That very early growth, even in utero, dictates the rest of life.”

During the lengthy study, researchers noted that the freezing ground event occurred every six years in 1996, 2002, and 2008. As climate change became more pronounced, the event started to happen every other year, in 2008, 2010, and 2012. Upon realising the frequency of the event, Albon said, “this was related to the warming climate. The Arctic is warming faster than anywhere else on the planet, especially this part of the Arctic.”

The disquieting information about reindeer size was simply a by-product of Albon and other researchers’ study on reindeers’ responses to parasites. In the course of their research measuring and weighing reindeer, they noticed a large disparity in the number of pregnant females in years with the rain-on-snow event. Additionally, researchers noted a decline in adults’ skeletal size and weight from the 1990s to early 2000s.  

An increase in overall temperature in the warm months yielded an abundance of food: “In the summer, 1.5 Celsius doesn’t sound like much, but if you increase from a mean of 6 degrees Celsius in July to 7.5 degrees Celsius, you’ll find you get a doubling in vegetation productivity.” Sadly, warmer summers did nothing to help the reindeer. Despite the bountiful food supply, the problem of foetal mortality and shrinking adult reindeers persisted. As if the reindeer of Svalbard needed another issue, the plentiful food in summer is causing reindeer to mate more often, increasing the population. In their report, Albon and co. posited that the increased population may factor into the lessened size of reindeer. These smaller reindeer are at a disadvantage in the winter since they have higher metabolisms but must deal with a shortage of food.

Researchers are waiting for reindeer born within the last couple years to reach maturity, at age 6. According to Albon, studying these specimens will better indicate the effect of climate change on reindeer population numbers. Another study presented at the American Geophysical Union Meeting on 12 December reported similar findings, citing climate change as the reason for shrinking reindeer populations in northern Russia. 

Jacqui Litvan

Jacqui Litvan, wielding a bachelor's degree in English, strives to create a world of fantasy amidst the ever-changing landscape of military life. Attempting to become a writer, she fuels herself with coffee (working as a barista) and music (spending free time as a raver).