Every year, reindeer migrate from the Norwegian islands of Arnoya and Kagen to winter pastures in Kautokeino on the mainland. ©SO JORD, flickr

Sometimes, even Santa’s strongest and swiftest assistants need a little help.

Reindeer in the Arctic lead a tough existence, depending on a delicate balance of climate, food supplies and predator/prey relationships to maintain their population numbers. A slight deviation in any of these factors can have dire consequences. And as climate change accelerates, that balance is disappearing.

Field data suggest that the predicted two- to four-degree temperature rise in the coming decades would result in an increase in the level of insect harassment and a corresponding loss of energy reserves in the reindeer. On top of that, some reindeer herds must achieve astounding physical feats that tax those energy reserves even more, such as this population in northern Norway, shown below. Every year, these animals must swim across chilly, just above-freezing Arctic waters. Their goal is to reach the mainland where they can get the lichen they need to make it through the winter.

Watch the video, in which reindeer from the islands Arnoya and Kagen cross a dangerous strait to their winter pastures in Kautokeino. Luckily, Santa’s helpers not only include reindeer, but reindeer herders.

Have happy holidays and a very merry Christmas,