Just in time for Christmas, researchers found the reason why Rudolf's nose was so bright red that fateful eve. Poor guy was desperate to cool down.
Reindeers sport a thick winter coat that warms them against the Arctic chill, fine when the animals are resting but fur that can overheat them during active times.
How do the animals manage their temperatures?
That's where the red nose comes in.
A trio of scientists sought to find out and observed reindeers on treadmills while monitoring their body temperatures and breathing rates.
Reindeer released excess heat first by panting with their mouths closed, then with their mouths open and then something unexpected happened, researchers found.
Reindeer started to cool their brains by diverting cold blood from their nose away from the body and into their heads. The animals essentially set up a heat exchange where cold blood from the nose cooled hot blood coming from the heart destined for the brain.
The researchers, Arnoldus Blix and Lars Folkow from the University of Tromsø, Norway along with Lars Walløe from the University of Oslo, Norway, published their findings online in the Journal of Experimental Biology on Thursday.
Blix said that initially he didn't think this strategy would work. Only 2 percent of the respiratory volume went through the nose when they resorted to open mouth panting, he says. However, when he calculated the colossal amounts of air inhaled by the exercising animals - coupled with the low air temperatures - it was clear that the reindeers were able to inhale sufficient cold air through their noses to keep their brains cool, but only as a last resort once the other cooling tactics were no longer sufficient.
Reindeer are the best animals to work with, Blix added. Once they trust the trainer they will do anything for you.