When summer temperatures climb above 20°C Norwegians often start complaining about the heat; so does the reindeer (Rangifer tarandus).

Reindeer are highly adapted to surviving in arctic and subarctic areas. Cold don`t bother them, but high temperatures are very stressful causing increased heart rates and panting. During such times, the animals seek cooler areas. At times they may lie down in moist bogs, but the best places to cool off are on the remaining alpine snow patches.

Permanent snow patches (those that don`t melt away during the summer) are usually situated in more north-facing and windy slopes. On hot summer days reindeer assemble on these patches, often spending large parts of the mid-day on or around the snow.

The colder air around these sites also have the added benefit of reducing the activities of parasitic insects, like warble flies and nose bots, that often harass reindeer. If the sites are used mainly to escape insects of the heat is debated, but once on the snow the patches provide some shelter from both.

On the snow and ice patches the animals are much calmer and are often unwilling to move off. They can then be approached to a closer distance. Due to this, such sites have been favored hunting sites for thousands of years. Saami reindeer herders have sometimes used these sites when marking calves or milking their domestic reindeer.

Due to all of the time reindeer spend on such sites, numerous traces of their activities have been left in the ice over long periods of time. Layers of hair and droppings are often found in ice core samples, and in melting ice patches large mats of reindeer dung can be revealed. Some animals have died on the sites, leaving their bones in the ice, while others have shed their antlers there.

For researchers this is great news, as such finds (often several thousand years old) provide important data about the history of reindeer as well as the humans that depended upon them.